This chapter describes basic interface configurations for your Layer 3 switch router. Also included are
sections about configuring virtual LANs (VLANs), packet-over-SONET interfaces, ATM uplink
interfaces, and port snooping.
Unless otherwise noted, the information in this chapter applies to the Catalyst 8540 CSR,
Catalyst 8510 CSR, and Catalyst 8540 MSR with Layer 3 functionality. For further information about
the commands used in this chapter, refer to the command reference publications in the Cisco IOS
documentation set and to Appendix A, “Command Reference.”
This chapter includes the following sections:
• Overview of Interface Configuration
• General Instructions for Configuring Interfaces
• About Layer 3 Switching Interfaces
• About Virtual LANs
• Configuring ISL VLAN Encapsulation
• Configuring 802.1Q VLAN Encapsulation
• About Packet over SONET (Catalyst 8540)
• Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
• About ATM Uplinks (Catalyst 8540)
• Configuring the ATM Uplink Interface (Catalyst 8540)
• About Port Snooping
• Configuring Snooping
NoteYou are at Step 3 in the suggested process for configuring your switch router (see the
“Suggested Procedure for Configuring Your Switch Router” section on page 2-1). You
should have already configured the processor module (and LAN emulation on the
Catalyst 8540 MSR) and now be ready to proceed with configuring interfaces.
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Overview of Interface Configuration
Overview of Interface Configuration
A router’s main function is to relay packets from one data link to another. Todo that, the characteristics
of the interfaces through which the packets are received and sent must be defined. Interface
characteristics include, but are not limited to, IP address, address of the port, data encapsulation
method, and media type.
Many features are enabled on a per-interface basis. Interface configuration mode contains commands
that modify the interface operation, for example, of an Ethernet port. When you issue the interface
command, you must define the interface type and number.
The following general guidelines apply to all physical and virtual interface configuration processes.
• Each interface must be configured with an IP address and an IP subnet mask.
• The virtual interfaces supported by Cisco switch routers include subinterfaces and IP tunnels.
A subinterface is a mechanism that allows a single physical interface to support multiple logical
interfaces or networks—that is, several logical interfaces or networks can be associated with a
single hardware interface. Configuring multiple virtual interfaces, or subinterfaces, on a single
physical interface allows greater flexibility and connectivity on the network.
Layer 3 interfaces have both a Media Access Control (MAC) address and an interface port ID. The
router keeps track of these designators and uses them to route traffic.
Chapter 4 Configuring Interfaces
Media Access Control Address
The MAC address, also referred to as the hardware address, is required for every port or device that
connects to a network. Other devices in the network use MAC addresses to locate specific ports in the
network and to create and update routing tables and data structures.
TipsTo find the MAC address for a device, use the show interfaces command.
Interface Port Identifier
The interface port identifier designates the physical location of the Layer 3 interface within the chassis.
This is the name that you use to identify the interface when configuring it. The system software uses
interface port identifiers to control activity within the switch router and to display status information.
Interface port identifiers are not used by other devices in the network; they are specific to the individual
switch router and its internal components and software.
You can find the interface port identifier on the rear of the switch router. It is composed of three parts,
formatted as slot/subslot/interface as depicted in Figure 4-1.
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Figure 4-1Interface Port Identifier Format
General Instructions for Configuring Interfaces
slot number / subslot number / interface number
The slot in which the
interface module or port
adapter is installed.
Slots are numbered
starting at 0.
The subslot in which the
interface module or port
adapter is installed. For a
full-width interface
module, this number is
always 0.
The port or interface
number on the interface
module or port adapter.
Numbering always starts
at 0 and goes from left to
right.
The interface port identifiers on the Ethernet modules remain the same regardless of whether other
modules are installed or removed. However, when you move an interface module to a different slot, the
first number in the address changes to reflect the new slot number.
You can identify module ports by physically checking the slot/subslot/interface location on the back of
the switch router. You can also use Cisco IOS show commands to display information about a specific
interface, or all the interfaces, in the switch router.
General Instructions for Configuring Interfaces
The following general configuration instructions apply to all interfaces. Begin in global configuration
mode. To configure an interface, follow these steps:
Step 1Use the configure EXEC command at the privileged EXEC prompt to enter the global configuration
Step 2Enter the interface command, followed by the interface type (for example, Fast Ethernet or Gigabit
Ethernet) and its interface port identifier (see the “Interface Port Identifier” section on page 4-2).
For example, to configure the Gigabit Ethernet port on slot 1, port 1, use this command:
Router(config)# interface gigabitethernet 1/0/1
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About Layer 3 Switching Interfaces
Step 3Follow each interface command with the interface configuration commands required for your
particular interface.
The commands you enter define the protocols and applications that will run on the interface. The
commands are collected and applied to the interface command until you enter another interface
command, a command that is not an interface configuration command, or you enter end to return to
privileged EXEC mode.
Step 4Check the status of the configured interface by using the EXEC show commands.
Router# show interface gigabitethernet 1/0/1
GigabitEthernet1/0/1 is up, line protocol is up
Hardware is K1 Gigabit Port, address is 00d0.ba1d.3207 (bia 00d0.ba1d.3207)
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
Full-duplex mode, 1000Mb/s, Auto-negotiation, 1000BaseSX
output flow-control is unsupported, input flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Chapter 4 Configuring Interfaces
About Layer 3 Switching Interfaces
Layer 3 switching supports two different Gigabit Ethernet interfaces, an eight-port module and a
two-port module. This section describes the initial configurations for both interface types.
TipsBefore you configure interfaces, be sure to have the interface network (IP or IPX)
addresses and the corresponding subnet mask information. If you do not have this
information, consult your network administrator.
The Gigabit Ethernet interface modules can be configured as trunk ports, non-trunking ports, routed
ports, or bridged ports. The trunk ports employ 802.1Q encapsulation; Inter-Switch Link (ISL) is not
supported. You can use the Gigabit Ethernet ports as routed interfaces, or you can configure the ports
into a bridge group, which is the recommended configuration.
By configuring as many ports as possible in a bridge group, you can optimize the throughput of your
switch router. You can also ensure that your networks are routed by using integrated routing and
bridging features from Cisco IOS software. For configuration instructions, see the “About Integrated
Routing and Bridging” section on page 6-4.
Between ports on the eight-port Gigabit Ethernet interface module itself, local switching at Layer 2
providesnonblocking performance at wire speed. For ports on this module configuredasabridge group,
Layer 2 traffic is processed at full Gigabit Ethernet rates. For Layer 3 traffic, however, this interface
module provides 2-Gbps routing bandwidth from the switch fabric.
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Initially Configuring Gigabit Ethernet Interfaces
To configure an IP address and autonegotiation on a Gigabit Ethernet interface, perform the following
steps, beginning in global configuration mode:
CommandPurpose
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Router(config)# interface gigabitethernet
slot/subslot/interface
Router(config-if)#
Router(config-if)# [no] negotiation autoSpecifies the negotiation mode.
Router(config-if)# ip address ip-address
subnet-mask
Router(config-if)# exit
Router(config)#
Router(config)# endReturns to privileged EXEC mode.
Router# copy system:running-config
nvram:startup-config
About Layer 3 Switching Interfaces
Enters Ethernet interface configuration mode to
configure the Gigabit Ethernet interface.
When you set negotiation mode to auto, the
Gigabit Ethernet port attempts to negotiate the
link (that is, both port speed and duplex setting)
with the partner port.
When you set the Gigabit Ethernet interface to nonegotiation auto, the port forces the link up no
matterwhatthepartnerportsettingis.Thisbrings
up the link with 1000 Mbps and full duplex only.
Specifiesthe IP address and IP subnet mask to be
assigned to the Gigabit Ethernet interface.
Returns to global configuration mode. Repeat
Steps 1 to 3 to configureanother Gigabit Ethernet
interface on this interface module.
Saves your configuration changes to NVRAM.
Example
The following example demonstrates initially configuring a Gigabit Ethernet interface with
autonegotiation and an IP address:
Router(config)# interface gigabitethernet 0/0/0
Router(config-if)# negotiation auto
Router(config-if)# ip address 10.1.2.3 255.0.0.0
Router(config-if)# exit
Router(config)# ^Z
C8540-CSR# copy system:running-config nvram:startup-config
About the Enhanced Gigabit Ethernet Interfaces (Catalyst 8540)
The enhanced Gigabit Ethernet interface module provides two Gigabit Ethernet interfaces with built-in
ACL support; no daughter card is required. The POS OC-12c uplink interface module and the ATM
uplink interface module also include a single enhanced Gigabit Ethernet interface. See “Configuringthe
POS OC-12c Uplink Interface (Catalyst 8540)” section on page 4-14” and “Configuring the ATM
Uplink Interface (Catalyst 8540)” section on page 4-28.
There is no special configuration required for the enhanced Gigabit Ethernet interfaces other than that
used for other Gigabit Ethernet interfaces.
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About Layer 3 Switching Interfaces
Initially Configuring Fast Ethernet Interfaces
Use the following procedure to assign an IP address to the Fast Ethernet 10BaseT or 100BaseT interface
of your switch router so that it can be recognized as a device on the Ethernet LAN. The Fast Ethernet
interface supports 10-Mbps and 100-Mbps speeds with Cisco 10BaseT and 100BaseT routers, hubs,
switches, and switch routers.
CommandDescription
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Router(config)# interface fastethernet
slot/subslot/interface
Router(config-if)#
Router(config-if)# ip address ip-address
subnet-mask
Router(config-if)# [no] speed [10 | 100 | auto]Configures the transmission speed for 10 or
Router(config-if)# [no] duplex [full | half | auto] Configures for full or half duplex. If you set
Router(config-if)# end
Router#
Router# copy system:running-config
nvram:startup-config
Chapter 4 Configuring Interfaces
Enters Ethernet interface configuration mode to
configure the Fast Ethernet interfaces.
Specifiesthe IP address and IP subnet mask to be
assigned to the FastEthernet interface.
100 Mbps, or for autonegotiation (the default). If
you set the speed to auto, you enable
autonegotiation, and the switch router matches
the speed of the partner node.
duplex for auto, the switch router matches the
duplex setting of the partner node.
Returns to privileged EXEC mode.
Saves your configuration changes to NVRAM.
Example
The following example demonstrates initially configuring a Fast Ethernet interface with an IP address
and autonegotiated speed and duplex:
Router(config)# interface fastethernet 1/0/0
Router(config-if)# ip address 10.1.2.4 255.0.0.0
Router(config-if)# speed auto
Router(config-if)# duplex auto
Router(config-if)# ^Z
Router# copy system:running-config nvram:startup-config
Verifying the Ethernet Interface Configuration
To verify the settings after you have configured Gigabit Ethernet or Ethernet 10/100 BaseT operation,
use the following commands:
CommandPurpose
show interface gigabitethernet
slot/subslot/interface
show interface fastethernet
slot/subslot/interface
Displays the status and global parameters of the
Gigabit Ethernet interface.
Displays the status and global parameters of the
Fast Ethernet interface.
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Examples
The following example shows sample output from the show interface gigabitethernet command:
Router# show interface gigabitethernet 0/0/0
GigabitEthernet0/0/0 is administratively down, line protocol is down
Hardware is K1 Gigabit Port, address is 00d0.ba1d.3207 (bia 00d0.ba1d.3207)
Internet address is 10.1.2.3/8
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
Full-duplex mode, 1000Mb/s, Auto-negotiation, 1000BaseSX
output flow-control is unsupported, input flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 watchdog, 0 multicast
0 input packets with dribble condition detected
0 packets output, 0 bytes, 0 underruns(0/0/0)
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
About Layer 3 Switching Interfaces
The following example shows sample output from the show interface fastethernet command:
Router# show interface fastethernet 1/0/0
FastEthernet1/0/0 is administratively down, line protocol is down
Hardware is epif_port, address is 0010.073c.050f (bia 0010.073c.050f)
Internet address is 10.1.2.4/8
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
Auto-duplex, Auto Speed, 100BaseTX
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 watchdog, 0 multicast
0 input packets with dribble condition detected
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
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About Virtual LANs
About Virtual LANs
Virtual LANs enable network managers to group users logically rather than by physical location. A
virtual LAN (VLAN) is an emulation of a standard LAN that allows data transfer and communication
to occur without the traditional restraints placed on the network. It can also be considered a broadcast
domain set up within a switch. With VLANs, switches can support more than one subnet (or VLAN) on
each switch, and give routers and switches the opportunity to support multiple subnets on a single
physical link. A group of devices on a LAN are configured so that they communicate as if they were
attached to the same LAN segment, when they are actually located on different segments. Layer 3
switching supports up to 255 VLANs per system.
VLANs enable efficient traffic separation and provide excellent bandwidth utilization. VLANs also
alleviate scaling issues by logically segmenting the physical LAN structure into different subnetworks
so that packets are switched only between ports within the same VLAN. This can be very useful for
security, broadcast containment, and accounting.
Layer 3 switching software supports a port-based VLAN on a trunk port, which is a port that carries the
traffic of multiple VLANs. Each frame transmitted on a trunk link is tagged as belonging to only one
VLAN.
Layer 3 switching software supports VLAN frame encapsulation through the Inter-Switch Link (ISL)
protocol and the 802.1Q standard.
Chapter 4 Configuring Interfaces
NoteThe four adjacent ports (such as 0 through 3, or 4 through 7) on a 10/100 interface must
all use the same VLAN encapsulation; that is, either 802.1Q and native, or ISL and native.
Configuring ISL VLAN Encapsulation
ISL is a Cisco protocol for interconnecting multiple switches and maintaining VLAN information as
traffic travels between switches.
The VLAN configuration example shown in Figure 4-2 depicts the following:
• Fast Ethernet port 1/0/0 and subinterface 1/0/1.1 on the switch router are in bridge group 1. They
are part of VLAN 50, which uses ISL encapsulation.
• Fast Ethernet port 3/0/1 and subinterface 1/0/1.2 are in bridge group 2. They are part of VLAN 100,
which uses ISL encapsulation.
• Fast Ethernet port 1/0/1 is configured as an ISL trunk.
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Figure 4-2Example of an ISL VLAN Bridging Configuration
Campus
switch
router
Bridge-group 1
1/0/0
1/0/1.1
VLAN 50
encap isl 50
encap isl 100
VLAN 100
Configuring ISL VLAN Encapsulation
Campus
switch
router
Step 1
Step 2
Step 3
3/0/1
Bridge-group 2
1/0/1.2
17489
To configure the Layer 3 VLANs shown in Figure 4-2, perform the following steps, beginning in global
configuration mode:
CommandPurpose
Router(config)# interface fastethernet
Enters subinterface configuration mode.
slot/subslot/interface.subinterface
Router(config-subif)#
Router(config-subif)# encapsulation isl vlan-idSpecifies ISL encapsulation for the Ethernet
frames sent from this subinterface with a
header that maintains the specified VLAN ID
between network nodes.
Router(config-subif)# bridge-group bridge-groupAssigns the subinterface a bridge group
number.
NoteWhen you are configuring VLAN
routing, skip this step.
Step 4
Router(config-subif)# interface fastethernet
slot/subslot/interface
Router(config-if)#
Step 5
Step 6
Router(config-if)# bridge-group bridge-groupAssigns the main interface to the bridge
Router(config-if)# exit
Router(config)#
Step 7
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Router(config)# bridge bridge-group protocol ieeeSpecifies that the bridge group will use the
Enters interface configuration mode to
configure the Fast Ethernet main interface.
group.
Returns to global configuration mode.
IEEE Ethernet Spanning Tree Protocol.
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Configuring 802.1Q VLAN Encapsulation
Example
The following example shows how to configure the interfaces for VLAN bridging with ISL
encapsulation shown in Figure 4-2:
When configuring ISL with IP, you cannot configure IP addresses on a subinterface unless the VLANs
are already configured (that is, you must have already entered the encapsulation isl or encapsulationdot1q command). That is not the case with IPX, however—you can configure IPX networks on a
subinterface even when the VLANs have not been configured.
The maximum VLAN bridge group values are as follows:
• Maximum number of bridge groups: 64
• Maximum number of interfaces per bridge group: 128
• Maximum number of subinterfaces per system: 255
For a complete configuration example for VLANs with ISL encapsulation, see the “Catalyst 8540 CSR
with ISL, VLAN, and BVI with GEC” section on page C-1.
To monitor the VLANs once they are configured, use the commands described in the “Monitoring
VLAN Operation” section on page 4-12.
Chapter 4 Configuring Interfaces
Configuring 802.1Q VLAN Encapsulation
The IEEE 802.1Q standard provides a method for secure bridging of data across a shared backbone.
IEEE 802.1Q VLAN encapsulation uses an internal, or one level, packet tagging scheme to multiplex
VLANs across a single physical link, while maintaining strict adherence to the individual VLAN
domains.
On an IEEE 802.1Q trunk port, all transmitted and received frames are tagged except for those on the
one VLAN configured as the PVID (port VLAN identifier) or native VLAN for the port. Frames on the
native VLAN are always transmitted untagged and are normally received untagged.
The VLAN configuration example shown in Figure 4-3 depicts the following:
• Fast Ethernet ports 1/0/0 and subinterface 1/0/1.1 on the switch router are in bridge group 1. They
are part of native VLAN 1, which uses 802.1Q encapsulation.
• Fast Ethernet port 3/0/1 and subinterface 1/0/1.2 are in bridge group 2. They are part of VLAN 100,
which uses 802.1Q encapsulation.
• Fast Ethernet port 1/0/1 is configured as an 802.1Q trunk.
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Figure 4-3Example of Bridging Between Native and Non-Native 802.1Q VLANs
Campus
switch
router
Bridge-group 1
1/0/0
1/0/1.1
Native VLAN 1
encap dot1q 1 native
encap dot1q 100
Non-native VLAN 100
Configuring 802.1Q VLAN Encapsulation
Campus
switch
router
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
3/0/1
Bridge-group 2
1/0/1.2
28089
To configure the bridging between native VLAN 1 and non-native VLAN 100 depicted in Figure 4-3,
perform the following steps:
CommandPurpose
Router(config)# interface fastethernet
Enters subinterface configuration mode.
slot/subslot/interface.subinterface
Router(config-subif)#encap dot1q vlan-id native Specifies 802.1Q encapsulation for Ethernet
frames sent from the subinterface with a header
that maintains the specified native VLAN ID
between network nodes.
Router(config-subif)# bridge-group
Assigns the subinterface a bridge group number.
bridge-group
NoteWhen you are configuring VLAN
routing, skip this step.
Router(config-subif)# interface fastethernet
slot/subslot/interface
Enters interface configuration mode to configure
the Fast Ethernet main interface.
Router(config-if)# bridge-group bridge-groupAssigns the main interface to the bridge group.
Router(config-if)# exitReturns to global configuration mode.
Router(config)# bridge bridge-group protocol
ieee
Specifies that the bridge group will use the IEEE
Ethernet Spanning Tree Protocol.
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Monitoring VLAN Operation
Example
The following example shows how to configure the bridging between native and non-native 802.1Q
VLANs shown in Figure 4-3:
Once the VLANs are configured on the switch router, you can monitor their operation using the
following commands:
CommandPurpose
show vlan vlan-idDisplays information on all configured VLANs or on a specific
VLAN (by VLAN ID number).
clear vlan vlan-idClears the counters for all VLANs, when the VLAN ID is not
specified.
debug vlan packetDisplays contents of the packets sent to and exiting from the route
processor.
To configure encapsulation over the EtherChannel, see the “About Encapsulation over EtherChannel”
section on page 7-6.
About Packet over SONET (Catalyst 8540)
Synchronous Optical Network (SONET) is an octet-synchronous multiplex scheme that definesafamily
of standard rates and formats. Optical specifications are defined for single-mode fiber and multimode
fiber. The transmission rates are integral multiples of 51.840 Mbps. For example, the POS OC-12c
uplink interface provides 622.080 Mbps over single-mode optical fiber.
POS provides for the serial transmission of data over SONET frames using either High-Level Data Link
Control (HDLC) protocol (the default) or Point-to-Point Protocol (PPP) encapsulation. On serial
interfaces, Cisco’s implementation provides error detection and synchronous framing functions of
traditional HDLC without the windowing or retransmission that are found in traditional HDLC.
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Because SONET/SDH (Synchronous Digital Hierarchy) is by definition a point-to-point circuit, PPP is
well suited for use over SONET links. The octet stream is mapped into the SONET/SDH synchronous
payload envelope (SPE) in accordance with RFC 2615, “PPP over SONET/SDH,”and RFC 2615, “PPP
in HDLC-like Framing.” Octet boundaries are aligned with the SPE octet boundaries, and the PPP
frames are located by row within the SPE payload. Because frames are variable in length, the frames
can cross SPE boundaries. Using this scheme, multiprotocol data can be encapsulated and transported
directly into SONET frames without relying on ATM to provide Layer 2 capability (for example, in IP
over ATM over SONET).
About the POS OC-12c Uplink Interface
POS technology is ideally suited for networks that are built for providing Internet or IP data. It provides
superior bandwidth utilization and efficiency over other transport methods. For expensive WAN links,
POS can provide as much as 25 to 30 percent higher throughput than ATM-based networks.
Transporting frames directly into the SONET/SDH payload eliminates the overhead required in ATM
cell header, IP over ATM encapsulation, and segmentation and reassembly (SAR) functionality.
Figure 4-4 shows a typical application of the POS OC-12c uplink interface module in an enterprise
setting. Here the enterprise backbone is comprised of POS links among Catalyst 8540 campus switch
routers in each building.
About the POS OC-12c Uplink Interface
Figure 4-4POS for Enterprise Backbone Connectivity
OC-12c POS
POS
OC-12c POS
OC-12c POS
OC-12c POS
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Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
Figure 4-5 shows an example of a service provider application of the POS OC-12c uplink interface
module. Here traffic is aggregated from Catalyst 8500 CSRs over POS OC-12c interfaces to Cisco
12000 GSRs. POS OC-48 interfaces on the Cisco 12000 gigabit switch routers then provide the uplinks
to the Internet backbone.
Figure 4-5POS for Aggregated Traffic Uplink to Internet
Internet
Backbone
Chapter 4 Configuring Interfaces
OC-48c/STM-16
OC-12c/STM-4 POS
Catalyst 8540s
Cisco 12000 GSRs
OC-12c/STM-4 POS
30747
Configuring the POS OC-12c UplinkInterface (Catalyst 8540)
This section describes the default configuration of the POS OC-12c uplink interface, initial
configurations you should perform for a newly installed interface, and optional configurations you can
do to customize the interfaces to the requirements of your network.
NoteThe POS OC-12c uplink interface module consists of one OC-12c port and one enhanced
Gigabit Ethernet port. For instructions on configuring the Gigabit Ethernet interface, see
the “AbouttheEnhanced Gigabit Ethernet Interfaces (Catalyst 8540)” section on page 4-5.
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Default Configuration
Table 4-1 shows the default configuration of an enabled POS OC-12c uplink interface. To change any
of these values, see the instructions in the following sections, “Initially Configuring the POS Interface”
and “Customizing the Configuration.”
Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
[no] mtu bytes4470 bytes
c2 (path signal byte) set to 0xcf;
s1s0 value}
j0 (section trace byte) set to
0xcc;
s1s0 (bit s1 and s0 of H1) set to 0
Initially Configuring the POS Interface
You should configure the following properties for a newly installed POS OC-12c uplink interface:
• IP routing
• IP address
• Encapsulation type
• Clock source
You should also configure the following properties to match those of the interface at the other end:
• Keepalive messages
• Cisco Discovery Protocol (CDP)
• Cyclic redundancy check (CRC)
• Scrambling
• Encapsulation type
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Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
To initially configure the POS OC-12c uplink interface, perform the following steps, beginning in
global configuration mode:
CommandPurpose
Step 1
Step 2
Router(config)# ip routingEnables IP routing.
Router(config)# interface pos
slot/subslot/interface
Router(config-if)#
Step 3
Router(config-if)# ip address
ip-address subnet-mask
Step 4
Router(config-if)# encapsulation
{hdlc | ppp}
Step 5
Router(config-if)# clock source
{line | internal}
Step 6
Router(config-if)# no shutdownEnables the interface with the previous configurations.
Chapter 4 Configuring Interfaces
Enters interface configuration mode and specifies the POS
interface to configure.
Assigns an IP address and subnet mask to the interface.
Specifies the encapsulation type.
Specifies the clock source for the interface. When clocking is
derived from the received clock, line (the default) is used. When
no line clocking source is available, internal is used.
Example
The following configuration is an example of the tasks in the preceding table:
Router(config)# interface pos 1/0/0
Router(config-if)# ip address 10.1.2.3 255.0.0.0
Router(config-if)# encapsulation ppp
Router(config-if)# clock source line
Router(config-if)# no shutdown
Automatic Reverting of Clock Source
If your system clock source is set to line clock, it uses the recovered received clock to transmit. Under
some conditions, the received clock is not reliable because of severe degradation of the signal quality.
Because your system software monitors SF (signal failure), it knows when there is severe degradation
in the signal quality and resorts to using the internal clock temporarily. Once the conditions that caused
the signal quality to deteriorate clear, your system reverts to the line clock.
When two POS interface modules are connected and configured with the default line clock, the signal
quality can degrade over time and both POS interfaces revert to the internal clock. As soon as the signal
quality improves, both POS interfaces revert to using the line clock. This cycle repeats itself causing
the line protocol on both interfaces to toggle. You can prevent this situation by configuring one end of
the connection with the default line clock and the other with the internal clock.
In addition, degradation in the signal quality causes an automatic reverting of the clock source under
the following conditions:
• SLOS (section loss of signal)
• SLOF (section loss of frame)
• AIS-L (line alarm indication signal)
• SF (signal failure) due to B2 error rate crossing the SF threshold value
• SF (signal failure) due to B3 error rate crossing the SF threshold value when the pos delay triggers
path command is configured
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Additional Configurations
To configure additional properties to match those of the interface at the far end, perform the following
steps, beginning in global configuration mode:
CommandPurpose
Step 1
Step 2
Step 3
NoteThe above steps apply both to the POS OC-12c uplink interface on the switch router and
Router(config-if)# no keepaliveTurns off keepalive messages. Keepalive messages, though not
Router(config-if)# no cdp enable Turns off CDP, which is not required.
Router(config-if)# crc {16 | 32}Sets the CRC value. If the device to which the POS module is
to the interface to which it connects at the far end.
Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
required, are recommended.
connected does not support the default CRC value of 32, set both
devices to use a value of 16.
Customizing the Configuration
This section describe how to customize the configuration of the POS OC-12c uplink interface to match
your network environment.
Setting the MTU Size
To set the maximum transmission unit (MTU), perform the following steps, beginning in global
configuration mode:
CommandPurpose
Step 1
Step 2
NoteThe POS OC-12c uplink interface supports IP unicast and IP multicast fragmentation. For
Router(config)# interface pos
slot/subslot/interface
Router(config-if)#
Router(config-if)# mtu bytesConfigures the MTU size up to a maximum of 9188 bytes. Default
IP unicast fragmentation, the packet must ingress on a POS interface and egress on any
interface. For IP multicast fragmentation, IP multicast data packets greater than
1500 bytes are fragmented to 1500 bytes on the ingress POS interface before being
switched to other members in the multicast group. All the members in the multicast group
must have a MTU equal to or greater than 1500 bytes.
Enters interface configuration mode and specifies the POS
interface to configure.
MTU size is 4470 bytes.
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Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
Configuring Framing
The default framing mode for the POS OC-12c uplink interface is SONET STS-12c. You can also
configuretheinterface for SDH STM-4, which is more widely used in Europe. To configurethe framing
mode on the POS OC-12c uplink interface, perform the following steps, beginning in global
configuration mode:
CommandPurpose
Step 1
Step 2
Step 3
Router(config)# interface pos
slot/subslot/interface
Router(config-if)#
Router(config-if)# pos framing
{sdh | sonet}
Router(config-if)# no shutdownEnables the interface with the previous configuration.
Chapter 4 Configuring Interfaces
Enters interface configuration mode and specifies the POS
interface to configure.
Configures the framing mode.
POS framing defaults to SONET. The following default values
are used for SONET.
• s1s0 default value is 0.
• J1 defaults set to host name, interface name, and IP address.
The following default values are used for SDH framing:
• s1s0 default value is 2.
• J1 is the path trace string. Its default setting is empty and is
not configurable.
Configuring SONET Overhead
You can set the SONET overhead bytes in the frame header to meet a specific standards requirement or
to ensure interoperability of the POS OC-12c uplink interface with another vendor's equipment. To
configure the SONET overhead, perform the following steps, beginning in global configuration mode:
CommandPurpose
Step 1
Step 2
Step 3
Router(config)# interface pos
slot/subslot/interface
Router(config-if)#
Router(config-if)# pos flag {c2
value | j0 value | sls0 value}
Router(config-if)# no shutdownEnables the interface with the previous configuration.
Enters interface configuration mode and specifies the POS
interface to configure.
Configures the SONET overhead bytes. c2 is a path signal
identifier, j0 is the section trace byte, and sls0 is the bit s1 and s0
of the H1 payload pointer byte.
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The value of the c2 byte is determined as follows:
• If the value of the c2 byte has not been explicitly configured with the pos flag command, the
SONET framer sends the following values:
• If the value of the c2 byte has been explicitly configured with the pos flagcommand,the configured
value is sent regardless of the encapsulation method.
The value of the s1s0 bits is determined as follows:
• If the value of the s1s0 bits have not been explicitly configured with the pos flag command, the
SONET framer sends the following values:
• If the value of the s1s0 bits have been explicitly configured with the pos flag command, the
configured value is used regardless of the framing.
Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
–
For Cisco HDLC encapsulation with or without SPE scrambling: 0xCF
–
For PPP encapsulation with scrambling: 0x16 (RFC 2615)
–
For PPP encapsulation without scrambling: 0xCF (RFC 2615)
–
For SONET framing, the default value is 0.
–
For SDH framing, the default value is 2.
Configuring POS SPE Scrambling
SONET payload scrambling applies a self-synchronous scrambler of polynomial X**43+1 to the
synchronous payload envelope (SPE) of the interface to ensure sufficient bit transition density. Both
ends of the connection must use the same scrambling algorithm.
To configure POS SPE scrambling, perform the following steps, beginning in global configuration
mode:
CommandPurpose
Step 1
Step 2
Step 3
Router(config)# interface pos
slot/subslot/interface
Router(config-if)#
Router(config-if)# no pos
scramble-atm
Router(config-if)# no shutdownEnables the interface with the previous configuration.
Enters interface configuration mode and specifies the POS
interface to configure.
Disables payload scrambling on the interface. Payload
scrambling is on by default.
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Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
Configuring SONET Alarms
The OC-12c POS uplink interface supports SONET alarm monitoring. To configure alarm monitoring,
perform the following steps, beginning in global configuration mode:
Router(config-if)# pos ais-shutSends a line alarm indication signal (AIS-L) to the other end of
Chapter 4 Configuring Interfaces
Enters interface configuration mode and specifies the POS
interface to configure.
Permits console logging of selected SONET alarms.
The alarms are as follows:
• b1-tca (B1 bit error rate [BER] threshold crossing alarm)
• b2-tca (B2 BER threshold crossing alarm)
• b3-tca (B3 BER threshold crossing alarm)
• lais (line alarm indication signal)
• lrdi (line remote defect indication)
• pais (path alarm indication signal)
• plop (path loss of pointer)
• prdi (path remote defect indication)
• plm-p (payload label, C2 mismatch alarm)
• sd-ber (LBIP BER in excess of threshold)
• sf-ber (signal failure BER)
• slof (section loss of frame)
• slos (section loss of signal), uneq-p (path unequipped C2
alarm).
The b1-tca, b2-tca, b3-tca, sf-ber, slof, and slos errors are
reported by default.
Sets the BER threshold values of the specified alarms. Default
values are 6 for b1-tca, b2-tca, b3-tca, and sd-ber; 3 for sf-ber.
the link after a shutdown command has been issued to the
specified POS interface. By default, the AIS-L is not sent to the
other end of the link.
You can stop transmitting the AIS-L by issuing either the
no shutdown or the no pos ais-shut commands.
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To determine which alarms are reported on the POS interface, and to display the BER thresholds, use
the show controllers pos command, as described in the next section, “Verifying the POS
Configuration” section on page 4-22. For a detailed description of the pos report and pos threshold
commands, refer to the Cisco IOS Interface Command Reference publication.
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Configuring SONET Delay Triggers
A trigger is an alarm, which when asserted causes the line protocol to go down.
Line and Section Triggers
Table 4-2 lists the line and section alarms that are triggers by default:
Table 4-2Default Line and Section Alarm Triggers
Alarm Description
SLOSSection loss of signal
SLOFSection loss of frame
AIS-L Line alarm indication signal
When one or more of the alarms in Table 4-2 are asserted, the line protocol of the interface goes down
without a delay. Youcan issue a pos delay triggers line command to delay triggering the line protocol
of the interface from going down. You can set the delay from 50 to 10000 ms. If you do not specify a
time interval, the default delay is set to 100 ms.
Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
Path Level Triggers
Table 4-3 lists path alarms that are not triggers by default. You can configure these path alarms as
triggers and also specify a delay.
Table 4-3Configurable Path Alarm Triggers
AlarmDescription
AIS-PPath alarm indication signal
RDI-PPath remote defect indication
LOP-PPath loss of pointer
You can issue the pos delay triggers path command to configure the path alarms listed in Table 4-3 as
triggers. These triggers will bring down the line protocol of the interface. When you configure the path
alarms as triggers, you can simultaneously specify a delay for the triggers. You can set the delay from
50 to 10000 ms. If you do not specify a time interval, the default delay is set to 100 ms.
The pos delay triggers path configuration can also bring the line protocol of the interface down when
the higher of the B2 and B3 error rates is compared with the SF (signal failure) threshold. If the SF
threshold is crossed, then the line protocol of the interface goes down.
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Configuring the POS OC-12c Uplink Interface (Catalyst 8540)
To configure a delay in triggering the line protocol of the interface from going down, perform the
following steps beginning in global configuration mode:
ATM uses cell-switching and multiplexing technology that combines the benefits of circuit switching
(constant transmission delay and guaranteed capacity) with those of packet switching (flexibility and
efficiency for intermittent traffic). ATM is a common network technology for enterprise backbones,
MANs, and WANs. By using an ATM uplink, Layer 3 traffic can be routed over an ATM network. The
ATM uplink facilitates this by segmenting packet data into fixed-size cells at the transmitting end and
reassembling them into packets at the receiving end. This conversion process is defined by the ATM
adaptation layer (AAL).
For further information about ATM and its implementation on the Catalyst 8540 MSR and
Catalyst 8510 MSR, refer to the Guide to ATM Technology.
About ATM Uplinks (Catalyst 8540)
About the ATM Uplink Interface
The ATM uplink interface allows the Catalyst 8540 switch router to be deployed as part of an existing
network where a router with an ATM interface would otherwise have been utilized. Additionally, the
ATM uplink interface allows a Catalyst 8540 deployed as a Layer 3 switch (CSR) to be connected to a
Catalyst 8540 deployed as an ATM switch (MSR).
Figure 4-6 shows an example application of the ATM uplink in which traffic from a LAN switch is
aggregated at the Catalyst 8540 CSR and then passed to the ATM network over the ATM uplink. The
Layer 3 enabled ATM uplink supports RFC 1483 (Multiprotocol Encapsulation over ATM), which
provides for the mapping of Layer 3 addresses to ATM virtual circuits, and traffic shaping. Refer to the
Guide to ATM Technology for additional information on RFC 1483.
Figure 4-6Layer 3 Traffic with ATM Uplink
Wiring closet
Catalyst 8540 CSR
ATM uplink
ATM network
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Chapter 4 Configuring Interfaces
Configuring the ATM Uplink Interface (Catalyst 8540)
NoteThe ATM uplink interface module does not work in a Catalyst 8540 MSR when the ATM
router module is present.
Configuring the ATM UplinkInterface (Catalyst 8540)
This section describes the default configurationof the ATM uplink interface, initial configurations you
should perform for a newly installed interface, and optional configurations you can do to customize the
interfaces to the requirements of your network.
NoteThe ATM uplink interface module consists of one OC-12c or OC-3c port and one
enhanced Gigabit Ethernet port. For instructions on configuring the enhanced Gigabit
Ethernet interface, see the “About the Enhanced Gigabit Ethernet Interfaces (Catalyst
8540)” section on page 4-5.
Configuration Overview
The following steps provide on overview of configuring an ATM uplink from the switch router to the
ATM network:
Step 1Configure the ATM uplink interface:
a. Enable the ATM interface.
b. Customize the configuration by configuring PVCs and SVCs.
You must configure at least one PVC or SVC. The VC options you configure must match in three
places: on the switch router, on the ATM switch, and at the remote end of the PVC or SVC
connection.
Step 2Configure the ATM switch to which the ATM uplink connects.
Default Configuration
On power up, the ATM uplink interface is shut down. When you enter the no shutdown command, the
interface is enabled with the default configuration values shown in Table 4-4.
Receive buffers for SAR8192
Maximum VCs8192
ATM AALAAL5
ILMI keepalivesNot supported
Configuring the ATM Uplink Interface (Catalyst 8540)
8192
Initially Configuring the ATM Uplink Interface
You should configure the following properties for a newly installed ATM uplink interface:
• IP routing
• IP address
To initially configure the ATM uplink interface, perform the following steps, beginning in global
configuration mode:
CommandPurpose
Step 1
Step 2
Step 3
Step 4
Step 5
Router(config)# ip routingEnables IP routing.
Router(config)# interface atm
slot/subslot/interface
Enters interface configuration mode and specifies the ATM
interface to configure.
Router(config-if)#
Router(config-if)# ip address
Assigns an IP address and subnet mask to the interface.
ip-address subnet-mask
Router(config-if)# atm clock
internal
Specifies the internal clock for the interface. The default mode
for the clock is no internal, which is the same as the line clock.
Router(config-if)# no shutdownEnables the interface with the previous configurations.
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Example
The following configuration is an example of the tasks in the preceding table:
Router(config)# interface atm 2/0/0
Router(config-if)# ip address 10.1.2.4 255.0.0.0
Router(config-if)# atm clock internal
Router(config-if)# no shutdown
Configuring the Clock Source
The ATMuplink interfaces support internal and line clock source. The default mode for the clock is no
internal, which is the same as the line clock. If your system clock source is set to line clock, it uses the
recovered received clock to transmit.
When two ATM uplink interfaces are connected and set to line clock, both interfaces at each end of the
link cannot accurately synchronize the clock. This causes transfer of corrupt data, which might cause
the line protocol on both interfaces to go down. To prevent this situation, make sure you configure one
end of the connection with internal clock and the other end with no internal clock.
When your system is configured to use the line clock, the following conditions cause the clock to
automatically revert to internal:
• SLOS (section loss of signal)
• SLOF (section loss of frame)
• AIS-L (line alarm indication signal)
• S1 (synchronizing status) byte in the SONET line overhead is equal to 0xF
When these conditions clear, the clock automatically restores to line clock.
Chapter 4 Configuring Interfaces
Customizing the Configuration
This section describes how to configure your ATM uplink interface to match your network
configuration.
Setting the MTU Size
To set the maximum transmission unit (MTU), perform the following steps, beginning in global
configuration mode:
CommandPurpose
Step 1
Step 2
Step 3
Router(config)# interface atm
slot/subslot/interface
Router(config-if)#
Router(config-if)# mtu bytesConfigures the MTU size with a value from 64 to 9188 bytes. The
Router(config-if)# no shutdownEnables the interface with the previous configuration.
Enters interface configuration mode and specifies the ATM
interface to configure.
default MTU size is 4478 bytes.
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NoteThe ATM uplink supports IP unicast and IP multicast fragmentation. For IP unicast
fragmentation, the packet must ingress on a ATM interface and egress on any interface.
For IP multicast fragmentation, IP multicast data packets greater than 1500 bytes are
fragmented to 1500 bytes on the ingress ATM interface before being switched to other
members in the multicast group. All the members in the multicast group must have a MTU
equal to or greater than 1500 bytes.
Configuring SONET Framing
In STM-1 mode or STM-4 mode, the ATM uplink interface sends idle cells for cell-rate decoupling. In
STS-3c mode or STS-12c mode, the interface sends unassigned cells for cell-rate decoupling. STS-3c
is the default SONET framing mode for the ATM OC-3c uplink interface; STS-12c is the default
SONET framing mode for the ATM OC-12c uplink interface.
To configure the SONET framing mode, perform the following steps, beginning in global configuration
mode:
Configuring the ATM Uplink Interface (Catalyst 8540)
CommandPurpose
Step 1
Router(config)# interface atm
slot/subslot/interface
Router(config-if)#
Step 2
Router(config-if)# atm sonet
stm-1
or
Router(config-if)# atm sonet
stm-4
Step 3
Router(config-if)# no shutdownEnables the interface with the previous configuration.
To return the SONET framing mode to the default, use the no form of the atm sonet command.
Configuring SONET Overhead
You can use the sonet overheadcommand to set the SONET overhead bytes in the frame header to meet
a specific standards requirement or to ensure interoperability of the ATM uplink interface with another
vendor's equipment. You can use the no form of this command to restore default values.
Enters interface configuration mode and specifies the ATM
interface to configure.
Configures the SONET framing mode to STM-1 (for the OC-3c
ATM interface) or to STM-4 (for the OC-12c interface).
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To configure the SONET overhead, perform the following steps, beginning in global configuration
mode:
NoteOn the ATMOC-3cinterface, you can configure the c2 byte and the s1s0 bits. On the ATM
Router(config-if)# no shutdownEnables the interface with the previous configuration.
OC-12c interface, you can configure the c2 byte, j0 byte, j1 byte, and the s1s0 bits.
Chapter 4 Configuring Interfaces
Enters interface configuration mode and specifies the ATM
interface to configure.
Configures the SONET overhead bytes. c2 is a path signal label
identifier, j0 is the section trace bytes, j1 is the path trace bytes,
and sls0 is part of the payload pointer byte.
The value of the c2 byte is determined as follows:
• If the value of the c2 byte has not been explicitly configured with the sonet overhead command,
the SONET framer sends the ATM payload value of 0x13.
• If the value of the c2 byte has been explicitly configured with the sonet overhead command, the
configured value is sent regardless of the encapsulation method.
The value of the s1s0 byte is determined as follows:
• If the value s1s0 bytes has not been explicitly configured with the sonet overhead command, the
SONET framer sends the following values:
–
For SONET framing, the default value is 0.
–
For SDH framing, the default value is 2.
• If the value of the s1s0 bits have been explicitly configured with the sonet overhead command, the
configured value is used regardless of the framing.
The value of the j0 and the j1 bytes are determined as follows:
• If the value of the j0 and the j1 bytes have not been explicitly configured with the sonet overhead
command, the SONET framer sets default values of 0x0 for both.
• If the user has specified a value using the sonet overhead command, the configured value is used
regardless of the framing.
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Configuring SONET Alarms
The ATM OC-12c and the ATM OC-3c uplink interfaces support SONET alarm monitoring. To
configure alarm monitoring, perform the following steps, beginning in global configuration mode:
The b1-tca, b2-tca, b3-tca, plop, sf-ber, slof, slos are enabled by
default.
Sets the BER threshold values of the specified alarms. Default
values are 6 for b1-tca, b2-tca, b3-tca, and sd-ber; 3 for sf-ber.
To determine which alarms are reported on the ATM interface, and to display the BER thresholds, use
the show controllers atm command, as described in the “Verifying the ATMConfiguration” section on
page 4-36. For a detailed description of the sonet report and sonet threshold commands, refer to the
ATM Switch Router Command Reference publication.
Configuring Loopback
The ATM uplink interface is configured by default with no loopback. To enable loopback, use the
loopback command in interface configuration mode.
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Configuring the ATM Uplink Interface (Catalyst 8540)
Configuring CDP
The ATM uplink interface is configured by default with Cisco Discovery Protocol (CDP) disabled. To
enable CDP, use the cdp enable command in interface configuration mode.
Configuring the Maximum VCs per VP
The ATM uplink interface is configured by default to allow a maximum of 1024 VCs per VP.To change
this value, perform the following steps, beginning in global configuration mode:
Router(config-if)# no shutdownEnables the interface with the previous configuration.
Chapter 4 Configuring Interfaces
Enters interface configuration mode and specifies the ATM
interface to configure.
Configures the maximum number of VCs per VP to 16, 32, 64,
128, 256, 512, 1024, 2048, 4096, or 8192.
Configuring Virtual Circuits
A virtual circuit is a point-to-point connection between the switch router and a remote system. A virtual
circuit is established for each ATM end node with which the router communicates. The characteristics
of the virtual circuit are established when the virtual circuit is created and include the following:
• Virtual circuit descriptor (VCD), associated with a VPI/VCI paid
• Encapsulation type
• Peak, average, and burst transmission rates
To configure a PVC, you must complete the following tasks:
• Create a PVC
• Map a protocol address to a PVC
Creating a PVC
When you create a PVC, you specify a virtual circuit descriptor (VCD) and associate it with the
VPI/VCI pair.The number chosen from the VCD is independent of the VPI/VCI used. When you create
a PVC, you also specify the AAL and encapsulation type and traffic parameters. Traffic parameters
include peak and average rate, specified in kilobits per second, and burst rate, specified in cells.
Omitting a peak and average value causes the PVC to be connected at the highest bandwidth rate
available. In that case, the peak and average values are equal.
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To create a PVC, perform the following steps, beginning in global configuration mode:
CommandPurpose
Step 1
Router(config)# interface atm
slot/subslot/interface
Router(config-if)#
Step 2
Router(config-if)# atm pvc vcd
vpi vci aal-encap
The atm pvc command allows you to specify additional optional parameters for the connection,
including peak, average, and burst transmission rate, and the frequency for generating OAM cells.
Mapping a Protocol Address to a PVC
Cisco IOS supports a mapping scheme that allows you to associate a protocol address with a VCD (for
PVCs) or with an ATM NSAP address (for SVCs). To create a mapping, you first create a map list, then
associate the map list to an interface.
To map a protocol address to a PVC, perform the following steps, beginning in global configuration
mode:
Configuring the ATM Uplink Interface (Catalyst 8540)
Enters interface configuration mode and specifies the ATM
interface to configure.
Configures the PVC with VCD value associated with a VPI/VCI
pair and specifies an encapsulation type.
PVC Example
Step 1
Step 2
Step 3
Step 4
Step 5
CommandPurpose
Router(config)# map-list nameCreates a map list and assigns it a name.
Router(config-map-list)# ip
ip-address atm-vc vcd
Router(config-map-list)# exit
Creates one or more map list entries, associating a protocol
address with a VCD.
Exits map-list configuration mode.
Router(config)#
Router(config)# interface atm
slot/subslot/interface
Enters interface configuration mode and specifies the ATM
interface to configure.
Router(config-if)#
Router(config-if)#map-group
Associates the map list with the interface.
name
You can create multiple map lists. An interface can have only one map list associated with it, but a map
list can be associated with multiple interfaces.
In the following example, PVC 5 is created on ATM interface 1/0/0 by means of LLC/sNAP
encapsulation over AAL5. ATM interface 1/0/0 (IP address 1.1.1.1) connects with the ATM interface
(IP address 1.1.1.5) at the other end over VC 5.
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Configuring the ATM Uplink Interface (Catalyst 8540)
SVC Example
In the following example, two switch routers with Layer 3 enabled ATM interfaces are connected by
means of SVCs. For SVCs, the map-list associates each IP addresses with an ATM NSAP-format
address, rather than with a specific VC. This configuration could also be used to connect two switch
routers with ATM interfaces through an ATM cloud of other switches:
• The PVC with VPI/VCI 0 5 must be configured for signaling to set up and tear down SVCs.
• The PVC with VPI/VCI 0 16 must be configured for switch management communication using
ILMI.
• The first 13 bytes of the ATM NSAP address is the prefix from the switch; the next 6 bytes is the
end system identifier (ESI) and must be unique. The last byte is the selector byte and is used in
making forwarding decisions.
Verifying the ATM Configuration
To verify the configuration on the ATM uplink interface, use the following commands:
CommandPurpose
show interfaces atmDisplays current ATM-specific information for the interface.
show atm vc [vcd]Displays current information about VCs and traffic. You can specify a
show atm trafficDisplays information about global traffic to and from all ATM networks
show controllers atmDisplays clock source, SONET alarms and error rates, and register values
VCD to display information about.
connected to the switch router.
to assist in troubleshooting.
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Chapter 4 Configuring Interfaces
Example
The following example shows sample output for the show interfaces atm command.
Router# show interfaces atm 0/0/0
ATM0/0/0 is down, line protocol is down
Hardware is epif_port_garfield, address is 0090.2157.c407 (bia 0090.2157.c407)
MTU 4470 bytes, sub MTU 4470, BW 155000 Kbit, DLY 10 usec, rely 0/255, load 1/
255
Encapsulation ATM, loopback not set, keepalive not supported
Full-duplex, Unknown Speed
ARP type: ARPA, ARP Timeout 04:00:00
Encapsulation(s): AAL5 AAL3/4, PVC mode
8191 maximum active VCs, 1024 VCs per VP, 0 current VCCs
VC idle disconnect time: 300 seconds
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
8 packets output, 2736 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
Configuring the ATM Uplink Interface (Catalyst 8540)
Example
The following example shows sample output for the show controllers atm command.
BER thresholds: SF = 10e-3 SD = 10e-6
TCA thresholds: B1 = 10e-6 B2 = 10e-6 B3 = 10e-6
About Port Snooping
Port-based snooping, or mirroring, lets you transparently mirror traffic from a source port(s) to a
destination port. Multiple snooping sessions can operate simultaneously. You can specify whether the
source ports are mirrored for transmit, receive, or both directions at once.
Port snooping augments the first four RMON groups (mini-RMON). For a description of RMON, see
the “Remote Monitoring” section on page 1-11.
Port-based snooping features include the following:
• Traffic on one or more source ports through a destination port in the same switch router
• Traffic from multiple source ports in multiple directions: transmitting, receiving, or both
• Multiple snoop destination ports operating simultaneously (however, there is only one destination
port per snooping session)
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Restrictions on Port Snooping
The following restrictions apply to port snooping:
• The combined physical bandwidth of the source ports must not exceed the physical bandwidth of
the destination port.
• The snooping source port and destination port cannot be the same port.
• Port snooping is not available on the eight-port Gigabit Ethernet interfaces.
About the Snooping Destination Port
The snooping destination port can be any port in the system, except for the management port on the
route processor (Ethernet0) and ports configured for Fast EtherChannel. Typically, the destination port
has a network analyzer or RMON probe attached to it.
When in snooping mode, all the existing connections to the snooping destination port are set to the down
state, and the snooping destination port cannot perform any Layer 2 or Layer 3 operations in this state.
The receive side of the snooping destination port is also disabled when in snooping mode. The snooping
destination port resumes normal operation only when snooping mode is disabled.
Configuring Snooping
About the Snooping Source Port
A source port is a port monitored by the snooping operation. The snooping source port can be on any
interface module.
The normal operation of a snooping source port is not altered during snooping operations. Any port with
bandwidth less than or equal to the bandwidth of the snooping destination port can function as a
snooping source port.
Layer 3 switching software supports snooping from multiple source ports to a destination port. The total
bandwidth of the snooping source ports must not exceed the bandwidth of the snooping destination port.
Forexample,up to ten Fast Ethernet ports can be configuredassnoopingsource ports to a 1-Gb Ethernet
destination port.
Configuring Snooping
To enable port-based snooping on an interface, perform the following steps, beginning in global
configuration mode:
NoteYou must shut down the destination interface before you enable snooping mode. To bring
the interface up after you have finished configuring snooping, be sure to issue a no
shutdown command.
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Defines the interface configuration for the
destination (test) port.
Router(config-if)# shutdownShuts down the destination port.
Router(config-if)# snoop interface source-port
direction {receive | transmit | both}
Defines a snoop source port and its snoop
direction. You must issue separate snoopinterface commands for each source port.
Router(config-if)# no shutdownReenables the interface. When you bring the
destination port back up, snooping mode is fully
functional.
Router(config-if)# end
Returns to privileged EXEC mode.
Router#
Router# copy system:running-config
Saves your configuration changes to NVRAM.
nvram:startup-config
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
For a complete configuration example that includes port snooping, see the “Catalyst 8540 CSR with
ISL, VLAN, and BVI with GEC” section on page C-1.
To disable port-based snooping on an interface, perform the following steps:
CommandPurpose
Router(config)# interface fastethernet
slot/subslot/interface
Enters interface configuration mode for the
previously configured destination port.
or
Router(config)# interface gigabitethernet
slot/subslot/interface
Router(config-if)#
Router(config-if)# shutdownShuts down the destination port.
Router(config-if)# no snoop interface
source-port
Disables port snooping by the destination port
defined in Step 1 on the indicated source port.
Router(config-if)# no shutdownReenables the interface. When you bring the
destination port back up, snooping mode is
disabled and any existing configuration and
connections are reestablished.
Router(config-if)# end
Returns to privileged EXEC mode.
Router#
Router# copy system:running-config
Saves your configuration changes to NVRAM.
nvram:startup-config
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NoteFor additional information on port snooping commands, refer to the “Port Snooping
Commands” section on page A-1.
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Monitoring Snooping
To monitor the current snooping mode configuration and status, use the following commands:
CommandPurpose
show snoop interface
destination-port
show snoopDisplays all the snoop sessions configured on the system.
show snoop-vc interface
destination-port
Now that you have configured the interfaces on your switch router, see Chapter 5, “Configuring
Networking Protocols,” for instructions on configuring network and routing protocols.
Monitoring Snooping
Displays whether the indicated destination port is in snooping
mode. If so, it indicates the source (monitored) port and the
snooping direction.
Displays the list of virtual circuits that are being monitored by the
destination port.
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