Cisco Systems BC-145 User Manual
Configuring Token Ring Inter-Switch Link
This chapter explains how to configure Token Ring Inter-Switch Link (TRISL) on Cisco routers. The
chapter describes TRISL in the context of the Inter-Switch Link (ISL) protocol and the Token
Ring VLAN concept.
For a complete description of the Token Ring Inter-Switch Link commands in this chapter, refer to the
“Token Ring Inter-Switch Link Commands” chapter in the Cisco IOS Bridging and IBM Networking
Command Reference (Volume 1 of 2). To locate documentation of other commands that appear in this
chapter, use the command reference master index or search online. For informati on on how Token Ring
VLANs are implemented on switches, refer to the Catalyst T oken Rin g Switching Implementat ion Guide,
the Catalyst 5000 Series T ok en Ring Confi gur ation Notes, the Catalyst 3900 Token Ring Switc hing Us er
Guide, and the Catalyst 3920 Token Ring Switching User Guide.
This chapter contains the following sections:
• Technology Overview, page 145
• TRISL Configuration Task List, page 148
• Monitoring TRISL Statistics, page 153
• TRISL Configuration Examples, page 154
To identify the hardware platform or software image information associated with a feature, use the
Feature Navigator on Cisco.com to search for information about the feature or refer to the software
release notes for a specific release. For more information, see the “Identifying Platform Support for
Cisco IOS Software Features” section on page li in the “Using Cisco IOS Software” chapter.
Technology Overview
Cisco’s TRISL Implementation
This section contains information related to Cisco’s implementation of TRISL that you should
understand before you proceed to the “TRISL Configuration Task List” section on page 148.
ISL and TRISL
ISL is a Layer 2 protocol that enables switches and routers to transport Ethernet frames from multiple
VLANs across Fast Ethernet or Gigabit Ethernet links. Cisco’s TRISL protocol extends the ISL model
to include the transport of Token Ring frames from multiple VLANs across these same links.
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Technology Overview
Configuring Token Ring Inter-Switch Link
TRISL support on Cisco routers provides inter-VLAN routing and bridging across a 100-Mb
Fast Ethernet link. ISL and TRISL together provide routing and bridging between Token Ring and
Ethernet LANs, ELANS, and VLANs.
TRISL is supported on the following platforms with any one of the following port adapters:
• Cisco 7500 or Cisco 7200 series routers
–
Two-port Fast Ethernet/ISL 100BaseTX
–
Two-port Fast Ethernet/ISL 100BaseFX
–
One-port Fast Ethernet 100BaseTX
–
One-port Fast Ethernet 100BaseFX
• Cisco 4500 or 4700 series routers
–
NM-1FE
• Cisco 3600 or 2600 series routers
–
NM-1FE1CE1
–
NM-1FE1CT1
–
NM-1FE1R2W
–
NM-1FE2CE1
–
NM-1FE2CT1
–
NM-1FE2W
–
NM-2FE2W
Note The two-port Fast Ethernet/ISL port adapters support frame sizes u p to 17800 bytes and t he one-port
Fast Ethernet port adapters support a frame size of up to 1500 bytes.
TRISL provides the following capabilities and features, which will be described in the “TRISL
Configuration Task List” section on page 148 and the “TRISL Configuration Examples” section on
page 154:
• IP routing for source-routed and non-source-routed frames between TRISL VLANs and any LAN,
ELAN, or VLAN.
• IPX routing for source-routed and non-source-routed frames between TRISL VLANs and any
LANs, ELANs, or VLANs.
• Source-Route Bridging (SRB) between TRISL VLANs and SRB-capable LANs, ELANs, or
VLANs.
• Source-Route Transparent Bridging (SRT) between TRISL VLANs and SRT-capable LANs,
ELANs, or VLANs.
• Source-Route Translational Bridging (SR/TLB) between TRISL VLANs and Ethernet LANs,
ELANs, or VLANs.
• Duplicate Ring Protocol (DRiP), which prevents external loops that could result if the router’s
virtual ring number were duplicated el sewhere in the network.
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Note VLAN Trunk Protocol (VTP) is currently not supported for TRISL on the routers.
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Configuring Token Ring Inter-Switch Link
S6813
Switch B
5
TrBRF 3
Token Ring VLANs
A VLAN is essentially a broadcast domain. In transparent bridging, there is only one type of broadcast
frame and, therefore, only one level of broadcast domain and one level of VLAN. In source routing,
however, there are two types of broadcast frames:
• Those that are confined to a single ring
• Those that traverse the bridged domain
Therefore, there are two levels of VLANs in a Token Ring switched network.
The first level is the Token Ring Concentrator Relay Function (TrCRF). At this level, the VLAN is a
logical ring and, as such, is assigned a ring number. On a Token Ring switch, the logical ring (TrCRF)
contains one or more physical ports. On a router , the logi cal ring (TrCRF) does not contain any physical
ports, but rather is used only in processing source-rou ted traffi c to terminate the routing information f ield
(RIF).
The second level is the Token Ring Bridge Relay Function (TrBRF). This is the parent VLAN to which
TrCRF VLANs are assigned. At this level, the VLAN is a logical bridge and, as such, is assigned a bridge
number. The logical bridge (TrBRF) contains the virtual ports that establish a connection between the
TrB RF a nd i t s TrC RFs . Th e TrB RF c a n be e xte nde d across a network of switches and routers via ISL,
as shown in Figure 52.
Technology Overview
Figure 52 Physical View of Switches Interconnected via ISL
Switch A
TrCRF
400
TrBRF 3
ISL
TrCRF
350
TrCRF
200
When you extend the T rBRF across an ISL link, you are essen tially e xtending the bridge across de vices,
as shown in Figure 53.
Figure 53 Logical View of Switches Interconnected via ISL
TrCRF
400
TrCRF
350
TrCRF
200
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Therefore, if you use source-route bridging between the TrCRFs that belong to the TrBRF, only one hop
appears in the RIF.
Traffic is switched between the ports in a TrCRF and bridged via SRB or SRT between the TrCRFs in a
TrBRF.
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TRISL Configuration Task List
1
Figure 54 illustrates a TrBRF that contains TrCRFs on both a router and a switch.
Figure 54 TrCRFs in a TrBRF
Configuring Token Ring Inter-Switch Link
TrCRF
TRISL
TrBRF
TRISL Configuration Task List
To configure and monitor TRISL in your network, perform one or more of the following tasks:
• Configuring IP Routing over TRISL, page 148
• Configuring Hot Standby Router Protocol over TRISL, page 149
• Configuring IPX Routing over TRISL, page 150
• Configuring Source-Route Bridging over TRISL, page 151
• Configuring Source-Route Transparent Bridging over TRISL, page 151
• Configuring Source-Route Translational Bridging over TRISL, page 152
See the “TRISL Configuration Examples” section on page 154 for examples.
TrCRF
Switch
TrCRF
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Configuring IP Routing over TRISL
The IP routing over TRISL VLANs feature e xtends IP routin g capabilities to inclu de support for routing
IP frame types in VLAN configurations. To configure IP routing over TRISL, use the following
commands beginning in global configuration mode:
Command Purpose
Step 1
Step 2
Step 3
Step 4
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Router(config)# ip routing
Router(config)# interface type
slot/port.subinterface-number
Router(config-if)# encapsulation
tr-isl trbrf-vlan vlanid bridge-num
bridge-number
Router(config-if)# ip address
ip-address mask
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Enables IP routing on the router.
Specifies the subinterface on which TRISL will be used.
Defines the encapsulation format, and specifies the VLAN identifier.
Sets a primary IP address for an interface.
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Configuring Token Ring Inter-Switch Link
You can configure TRISL to route source-routed traffic by enabling the collection and use of RIF
information on a TRISL subinterface. This creates a “pseudoring” to terminate the RIF path on a ring.
Without RIF i nformation, a packet could not be bridged across a source-route brid ged network connected
to this interface.
To route source-routed traffic, use the following additional commands in interface configuration mode:
Command Purpose
Step 1
Step 2
Router(config-if)# multiring
trcrf-vlan vlanid ring
Router(config-if)# multiring
{protocol-keyword [all-routes |
spanning | all | other]}
Note TRISL encapsulation must be specified for a subinterface before an IP address can be assigned to that
subinterface.
TRISL Configuration Task List
Creates a pseudoring to terminate the RIF and assigns it to a VLAN.
ring-number
Enables collection and use of RIF information with routed protocols.
Configuring Hot Standby Router Protocol over TRISL
The Hot Standby Router Protocol (HSRP) provides fault tolerance and enhanced routing performance
for IP networks. HSRP allows Cisco routers to monitor each other’s operational status and very quickly
assume packet forwarding responsibility in the event the current forwarding device in the HSRP group
fails or is taken do wn for maintenance. The standb y mechanism remai ns transparent to the attached hosts
and can be deployed on any LAN type. With multiple hot-standby groups, routers can simultaneously
provide redundant backup and perform load-sharing across different IP subsets.
To configure HSRP over TRISL between VLANs, use the following commands beginning in global
configuration mode:
Command Purpose
Step 1
Step 2
Step 3
Step 4
Router(config)# interface type
slot/port subinterface-number
Router(config-if)# encapsulation
tr-isl trbrf-vlan vlanid bridge-num
bridge-number
Router(config-if)# ip address
ip-address mask [secondary]
Router(config-if)# standby
[group-number] ip
[ip-address [secondary]]
Specifies the subinterface on which ISL will be used.
Defines the encapsulation format, and specify the VLAN identifier.
Specifies the IP address for the subnet on which ISL will be used.
Enables HSRP.
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TRISL Configuration Task List
T o customize hot standb y group attributes, use one of the follo wing commands in interface conf iguration
mode, as needed:
Command Purpose
Router(config-if)# standby [group-number]
timers hellotime holdtime
Router(config-if)# standby [group-number]
priority priority
Router(config-if)# standby [group-number]
preempt
Configures the time between hello packets and the hold time before
other routers declare the active router to be down.
Sets the hot standby priority used to choose the active router.
Specifies that if the local router has priority over the current active
router, the local router should attempt to take its place as the active
router.
Router(config-if)# standby [group-number]
track type-number [interface-priority].
Configures the interface to track other interfaces, so that if one of th e
other interfaces goes down, the hot standby priority for the device is
lowered.
Router(config-if)# standby [group-number]
authentication string
Enables the automatic spanning-tree function on a group of bridged
interfaces.
Configuring Token Ring Inter-Switch Link
Configuring IPX Routing over TRISL
The IPX Routing over ISL VLANs feature extends Novell NetWare routing capabilities to include
support for routing all standard IPX encapsulations for Token Ring frame types in VLAN configurations.
Users with Novell NetW are en vironments can configure either SAP or SN AP encapsulations to be routed
using the TRISL encapsulation across VLAN boundaries.
Netware users can now configure consolidated VLAN routing over a single VLAN trunking interface.
With configurable Token Ring encapsulation protocols on a per VLAN basis, u sers have the flexibility
of using VLANs regardless of their NetWare Token Ring encapsulation. Encapsulation types and
corresponding framing types are described in the “Configuring Novell IPX” chapter of the Cisco IOS
AppleTalk and Novell IPX Configuration Guide.
Note Only one type of IPX encapsulation can be configured per VLAN (subinterface). The IPX
encapsulation used must be the same within any particular subnet. A single encapsulation must be
used by all NetWare systems that belong to the same LAN.
To configure Cisco IOS software to route IPX on a router with connected VLANs, use the following
commands beginning in global configuration mode:
Command Purpose
Step 1
Step 2
Step 3
Step 4
Step 5
Router(config)# ipx routing [node]
Router(config)# interface type
slot/port.subinterface-number
Router(config-if)# encapsulation
tr-isl trbrf-vlan vlanid bridge-num
bridge-number
Router(config-if)# ipx encapsulation
encapsulation-type
Router(config-if)# ipx network
network number
Enables IPX routing globally.
Specifies the subinterface on which TRISL will be used.
Defines the encapsulation for TRISL.
Specifies the IPX encapsulation.
Specifies the IPX network.
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Note The default IPX encapsulation format for Token Ring in Cisco IOS routers is SAP. Therefore, you
only need to explicitly configure the IPX encapsulation type if your Token Ring network requires
SNAP encapsulation instead of SAP.
When routing source-routed traffic for specific VLANs, use the following additional commands in
interface configuration mode:
Command Purpose
Step 1
Step 2
Router(config-if)# multiring
trcrf-vlan vlanid
ring-number
Router(config-if)# multiring
{protocol-keyword [all-routes |
spanning | all | other]}
trcrf-ring
Creates a pseudoring to terminate the RIF and assign it to a VLAN.
Enables collection and use of RIF information with routed protocols.
Configuring Source-Route Bridging over TRISL
TRISL Configuration Task List
To configure SRB over TRISL, use the following commands beginning in global configuration mode:
Command Purpose
Step 1
Step 2
Step 3
Step 4
Router(config)# source-bridge
ring-group vring-num
Router(config)# interface type
slot/port.subinterface-number
Router(config-if)# encapsulation
tr-isl trbrf-vlan vlanid bridge-num
bridge-number
Router(config-if)# source-bridge
trcrf-vlan vlanid ring-group
ring-number
Configures a virtual ring for the router.
Specifies the subinterface on which TRISL will be used.
Defines the encapsulation for TRISL.
Attaches a TrCRF VLAN identifier to the router’s virtual ring.
Configuring Source-Route Transparent Bridging over TRISL
To configure transparent bridging over TRISL, use the following command beginning in global
configuration mode:
Command Purpose
Step 1
Step 2
Step 3
Router(config)# interface type
slot/port.subinterface-number
Router(config-if)# encapsulation
tr-isl trbrf-vlan vlanid bridge-num
bridge-number
Router(config-if)# bridge-group
bridge-group number
Specifies the subinterface on which TRISL will be used.
Defines the encapsulation for TRISL.
Specifies the bridge group to which the TRISL subinterface belongs.
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TRISL Configuration Task List
Configuring Source-Route Translational Bridging over TRISL
T o conf i gure source-r oute translat ional bridgi ng ov er TRISL, use the following commands beginning in
global configuration mode:
Command Purpose
Step 1
Step 2
Step 3
Step 4
Step 5
Router(config)# source-bridge ring-group vring-num
Router(config)# source-bridge transparent ring-group
pseudoring bridge-number tb-group [oui]
Router(config)# interface type
slot/port.subinterface-number
Router(config-if)# encapsulation tr-isl trbrf-vlan
vlanid bridge-num bridge-number
Router(config-if)# source-bridge trcrf-vlan vlanid
ring-group ring-number
Configures a virtual ring for the router.
Enables bridging between transparent bridging and
source-route bridging.
Specifies the subinterface on which TRISL will be
used.
Defines the encapsulation for TRISL.
Assigns a VLAN ID to the router’s virtual ring.
Note For a complete description of SR/TLB, including configuring translation compatibility with IBM
8209 bridges and configuring Token Ring LLC2 to Ethernet Type II (0x80d5) and Token Ring LLC2
to Ethernet 802.3 LLC2 (standard) translations, please refer to the “Configuring Source-Route
Bridging” chapter in this publication and “Source-Route Bridging Commands” chapter in the Cisco
IOS Bridging and IBM Command Reference (Volume 1 of 2).
Configuring Automatic Spanning Tree
The automatic spanning-tree function supports automatic resolution of spanning trees i n SRB network s,
which provides a single path for spanning explorer frames to traverse from a given node in the network
to another. Spanning explorer frames have a single-route broadcast indicator set in the routing
information field. Port identif iers consist of ri ng numbers and bridge numbers associated with the ports.
The spanning-tree algorithm for SRB does n ot suppor t Topology Change Notification Bridge Protocol
Data Unit (BPDU).
Although the automatic spanning-tree function can be configured with Source-Route Translational
Bridging (SR/TLB), the SRB domain and transparent bridging domain have separate spanning trees.
Each Token Ring interface can belong to only one spanning tree. Only one bridge group can run the
automatic spanning-tree function at a time.
To create a bridge group that runs an automatic spanning-tree function compatible with the IBM SRB
spanning-tree implementation, use the following command in global configuration mode:
Command Purpose
Router(config)# bridge bridge-group
protocol ibm
Creates a bridge group that runs the automatic spanning-tree function.
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