Cisco Catalyst 9500 series Configuration Manual
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
First Published: 2017-07-31
Last Modified: 2017-11-03
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CONTENTS
CHAPTER 1
Configuring Bidirectional Forwarding Detection 1
Bidirectional Forwarding Detection 1
Finding Feature Information 1
Prerequisites for Bidirectional Forwarding Detection 1
Restrictions for Bidirectional Forwarding Detection 2
Information About Bidirectional Forwarding Detection 2
BFD Operation 2
Neighbor Relationships 2
BFD Detection of Failures 3
BFD Version Interoperability 3
BFD Session Limits 4
BFD Support for Nonbroadcast Media Interfaces 4
BFD Support for Nonstop Forwarding with Stateful Switchover 4
BFD Support for Stateful Switchover 4
BFD Support for Static Routing 4
Benefits of Using BFD for Failure Detection 5
How to Configure Bidirectional Forwarding Detection 6
Configuring BFD Session Parameters on the Interface 6
Configuring BFD Support for Dynamic Routing Protocols 7
Configuring BFD Support for eBGP 7
Configuring BFD Support for EIGRP 8
Configuring BFD Support for IS-IS 10
Prerequisites 10
Configuring BFD Support for IS-IS for All Interfaces 11
Configuring BFD Support for IS-IS for One or More Interfaces 12
Configuring BFD Support for OSPF 13
Configuring BFD Support for OSPF for All Interfaces 14
Configuring BFD Support for OSPF for One or More Interfaces 15
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Contents
Configuring BFD Support for HSRP 17
Configuring BFD Support for Static Routing 18
Configuring BFD Echo Mode 21
Prerequisites 21
Restrictions 21
Disabling BFD Echo Mode Without Asymmetry 21
Creating and Configuring BFD Templates 22
Configuring a Single-Hop Template 22
Monitoring and Troubleshooting BFD 23
Monitoring and Troubleshooting BFD 23
Feature Information for Bidirectional Forwarding Detection 24
CHAPTER 2
Configuring MSDP 25
Information About Configuring MSDP 25
MSDP Overview 25
MSDP Operation 26
MSDP Benefits 27
How to Configure MSDP 28
Default MSDP Configuration 28
Configuring a Default MSDP Peer 28
Caching Source-Active State 30
Requesting Source Information from an MSDP Peer 31
Controlling Source Information that Your Switch Originates 32
Redistributing Sources 33
Filtering Source-Active Request Messages 35
Controlling Source Information that Your Switch Forwards 36
Using a Filter 36
Using TTL to Limit the Multicast Data Sent in SA Messages 39
Controlling Source Information that Your Switch Receives 40
Configuring an MSDP Mesh Group 42
Shutting Down an MSDP Peer 43
Including a Bordering PIM Dense-Mode Region in MSDP 44
Configuring an Originating Address other than the RP Address 46
Monitoring and Maintaining MSDP 47
Configuration Examples for Configuring MSDP 48
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Contents
Configuring a Default MSDP Peer: Example 48
Caching Source-Active State: Example 49
Requesting Source Information from an MSDP Peer: Example 49
Controlling Source Information that Your Switch Originates: Example 49
Controlling Source Information that Your Switch Forwards: Example 49
Controlling Source Information that Your Switch Receives: Example 50
Feature Information for Multicast Source Discovery Protocol 50
CHAPTER 3
Configuring IP Unicast Routing 51
Information About Configuring IP Unicast Routing 52
Information About IP Routing 52
Types of Routing 53
Classless Routing 53
Address Resolution 55
Proxy ARP 55
ICMP Router Discovery Protocol 55
UDP Broadcast Packets and Protocols 56
Broadcast Packet Handling 56
IP Broadcast Flooding 57
How to Configure IP Routing 57
How to Configure IP Addressing 58
Default IP Addressing Configuration 59
Assigning IP Addresses to Network Interfaces 60
Using Subnet Zero 61
Disabling Classless Routing 62
Configuring Address Resolution Methods 63
Defining a Static ARP Cache 63
Setting ARP Encapsulation 65
Enabling Proxy ARP 66
Routing Assistance When IP Routing is Disabled 68
Proxy ARP 68
Default Gateway 68
ICMP Router Discovery Protocol (IRDP) 69
Configuring Broadcast Packet Handling 71
Enabling Directed Broadcast-to-Physical Broadcast Translation 71
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Forwarding UDP Broadcast Packets and Protocols 73
Establishing an IP Broadcast Address 75
Flooding IP Broadcasts 76
Monitoring and Maintaining IP Addressing 77
How to Configure IP Unicast Routing 78
Enabling IP Unicast Routing 78
Example of Enabling IP Routing 79
What to Do Next 79
Information About RIP 80
Summary Addresses and Split Horizon 80
How to Configure RIP 81
Default RIP Configuration 81
Configuring Basic RIP Parameters 82
Configuring RIP Authentication 84
Configuring Summary Addresses and Split Horizon 85
Configuring Split Horizon 87
Configuration Example for Summary Addresses and Split Horizon 88
Information About OSPF 89
OSPF Nonstop Forwarding 89
OSPF NSF Awareness 90
OSPF NSF Capability 90
OSPF Area Parameters 90
Other OSPF Parameters 90
LSA Group Pacing 91
Loopback Interfaces 91
How to Configure OSPF 92
Default OSPF Configuration 92
Configuring Basic OSPF Parameters 93
Configuring OSPF Interfaces 95
Configuring OSPF Area Parameters 97
Configuring Other OSPF Parameters 99
Changing LSA Group Pacing 101
Configuring a Loopback Interface 102
Monitoring OSPF 103
Configuration Examples for OSPF 104
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Contents
Example: Configuring Basic OSPF Parameters 104
Information About EIGRP 104
EIGRP Features 104
EIGRP Components 105
EIGRP Nonstop Forwarding 106
EIGRP NSF Awareness 106
EIGRP NSF Capability 106
EIGRP Stub Routing 106
How to Configure EIGRP 107
Default EIGRP Configuration 108
Configuring Basic EIGRP Parameters 109
Configuring EIGRP Interfaces 111
Configuring EIGRP Route Authentication 113
Monitoring and Maintaining EIGRP 115
Information About BGP 115
BGP Network Topology 115
Nonstop Forwarding Awareness 117
Information About BGP Routing 117
Routing Policy Changes 117
BGP Decision Attributes 118
Route Maps 119
BGP Filtering 119
Prefix List for BGP Filtering 120
BGP Community Filtering 120
BGP Neighbors and Peer Groups 121
Aggregate Routes 121
Routing Domain Confederations 121
BGP Route Reflectors 121
Route Dampening 122
More BGP Information 122
How to Configure BGP 122
Default BGP Configuration 122
Enabling BGP Routing 126
Managing Routing Policy Changes 128
Configuring BGP Decision Attributes 129
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Configuring BGP Filtering with Route Maps 131
Configuring BGP Filtering by Neighbor 132
Configuring BGP Filtering by Access Lists and Neighbors 133
Configuring Prefix Lists for BGP Filtering 135
Configuring BGP Community Filtering 136
Configuring BGP Neighbors and Peer Groups 137
Configuring Aggregate Addresses in a Routing Table 140
Configuring Routing Domain Confederations 141
Configuring BGP Route Reflectors 143
Configuring Route Dampening 144
Monitoring and Maintaining BGP 145
IS-IS Routing 147
IS-IS Dynamic Routing 147
Nonstop Forwarding Awareness 147
IS-IS Global Parameters 148
IS-IS Interface Parameters 148
How to Configure IS-IS Routing 149
Default IS-IS Configuration 149
Enabling IS-IS Routing 150
Configuring IS-IS Global Parameters 152
Configuring IS-IS Interface Parameters 155
Monitoring and Maintaining IS-IS 158
Information About Multi-VRF CE 158
Understanding Multi-VRF CE 159
Network Topology 159
Packet-Forwarding Process 160
Network Components 161
VRF-Aware Services 161
How to Configure Multi-VRF CE 161
Default Multi-VRF CE Configuration 161
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Multi-VRF CE Configuration Guidelines 162
Configuring VRFs 163
Configuring VRF-Aware Services 164
Configuring VRF-Aware Services for ARP 165
Configuring VRF-Aware Services for Ping 165
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Configuring VRF-Aware Services for SNMP 165
Configuring VRF-Aware Servcies for uRPF 166
Configuring VRF-Aware RADIUS 168
Configuring VRF-Aware Services for Syslog 168
Configuring VRF-Aware Services for Traceroute 169
Configuring VRF-Aware Services for FTP and TFTP 169
Configuring Multicast VRFs 170
Configuring a VPN Routing Session 173
Configuring BGP PE to CE Routing Sessions 174
Monitoring Multi-VRF CE 175
Configuration Examples for Multi-VRF CE 176
Multi-VRF CE Configuration Example 176
Configuring Unicast Reverse Path Forwarding 179
Protocol-Independent Features 179
Distributed Cisco Express Forwarding 180
Information About Cisco Express Forwarding 180
How to Configure Cisco Express Forwarding 180
Number of Equal-Cost Routing Paths 182
Information About Equal-Cost Routing Paths 182
How to Configure Equal-Cost Routing Paths 183
Static Unicast Routes 183
Information About Static Unicast Routes 183
Configuring Static Unicast Routes 184
Default Routes and Networks 186
Information About Default Routes and Networks 186
How to Configure Default Routes and Networks 186
Route Maps to Redistribute Routing Information 187
Information About Route Maps 187
How to Configure a Route Map 187
How to Control Route Distribution 191
Policy-Based Routing 193
Information About Policy-Based Routing 193
How to Configure PBR 194
Filtering Routing Information 197
Setting Passive Interfaces 197
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Contents
Controlling Advertising and Processing in Routing Updates 199
Filtering Sources of Routing Information 200
Managing Authentication Keys 201
Prerequisites 201
How to Configure Authentication Keys 201
Monitoring and Maintaining the IP Network 203
Feature Information for IP Unicast Routing 203
CHAPTER 4
Configuring Generic Routing Encapsulation(GRE) Tunnel IP Source and Destination VRF
Membership 205
Restrictions for GRE Tunnel IP Source and Destination VRF Membership 205
Information About GRE Tunnel IP Source and Destination VRF Membership 206
How to Configure GRE Tunnel IP Source and Destination VRF Membership 206
Configuration Example for GRE Tunnel IP Source and Destination VRF Membership 207
Additional References 208
Feature History for Generic Routing Encapsulation Tunnel IP Source and Destination VRF
Membership 209
Notices 211
Trademarks 211
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Configuring Bidirectional Forwarding Detection
Bidirectional Forwarding Detection, page 1
•
Bidirectional Forwarding Detection
This document describes how to enable the Bidirectional Forwarding Detection (BFD) protocol. BFD is a
detection protocol that is designed to provide fast forwarding path failure detection times for all media types,
encapsulations, topologies, and routing protocols.
BFD provides a consistent failure detection method for network administrators, in addition to fast forwarding
path failure detection. Because the network administrator can use BFD to detect forwarding path failures at
a uniform rate, rather than the variable rates for different routing protocol hello mechanisms, network profiling
and planning will be easier, and reconvergence time will be consistent and predictable.
Finding Feature Information
CHAPTER 1
Your software release may not support all the features documented in this module. For the latest caveats and
feature information, see Bug Search Tool and the release notes for your platform and software release. To
find information about the features documented in this module, and to see a list of the releases in which each
feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not
required.
Prerequisites for Bidirectional Forwarding Detection
Cisco Express Forwarding and IP routing must be enabled on all participating switches.
•
One of the IP routing protocols supported by BFD must be configured on the switches before BFD is
•
deployed. You should implement fast convergence for the routing protocol that you are using. See the
IP routing documentation for your version of Cisco IOS software for information on configuring fast
convergence. See the Restrictions for Bidirectional Forwarding Detection section for more information
on BFD routing protocol support in Cisco IOS software.
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Configuring Bidirectional Forwarding Detection
Restrictions for Bidirectional Forwarding Detection
Restrictions for Bidirectional Forwarding Detection
BFD works only for directly connected neighbors. BFD neighbors must be no more than one IP hop
•
away. Multihop configurations are not supported.
BFD support is not available for all platforms and interfaces. To confirm BFD support for a specific
•
platform or interface and obtain the most accurate platform and hardware restrictions, see the Cisco IOS
software release notes for your software version.
BFD packets are not matched in the QoS policy for self-generated packets.
•
BFD packets are matched in the class class-default command. So, the user must make sure of the
•
availability of appropriate bandwidth to prevent dropping of BFD packets due to oversubscription.
BFD HA support is not available starting Cisco Denali IOS XE 16.3.1
•
Information About Bidirectional Forwarding Detection
BFD Operation
BFD provides a low-overhead, short-duration method of detecting failures in the forwarding path between
two adjacent routers, including the interfaces, data links, and forwarding planes.
BFD is a detection protocol that you enable at the interface and routing protocol levels. Cisco supports BFD
asynchronous mode, which depends on the sending of BFD control packets between two systems to activate
and maintain BFD neighbor sessions between routers. Therefore, in order for a BFD session to be created,
you must configure BFD on both systems (or BFD peers). Once BFD has been enabled on the interfaces and
at the router level for the appropriate routing protocols, a BFD session is created, BFD timers are negotiated,
and the BFD peers will begin to send BFD control packets to each other at the negotiated interval.
Neighbor Relationships
BFD provides fast BFD peer failure detection times independently of all media types, encapsulations, topologies,
and routing protocols BGP, EIGRP, IS-IS, and OSPF. By sending rapid failure detection notices to the routing
protocols in the local router to initiate the routing table recalculation process, BFD contributes to greatly
reduced overall network convergence time. The figure below shows a simple network with two routers running
OSPF and BFD. When OSPF discovers a neighbor (1) it sends a request to the local BFD process to initiate
a BFD neighbor session with the OSPF neighbor router (2). The BFD neighbor session with the OSPF neighbor
router is established (3).
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Configuring Bidirectional Forwarding Detection
The figure below shows what happens when a failure occurs in the network (1). The BFD neighbor session
with the OSPF neighbor router is torn down (2). BFD notifies the local OSPF process that the BFD neighbor
is no longer reachable (3). The local OSPF process tears down the OSPF neighbor relationship (4). If an
alternative path is available, the routers will immediately start converging on it.
A routing protocol needs to register with BFD for every neighbor it acquires. Once a neighbor is registered,
BFD initiates a session with the neighbor if a session does not already exist.
OSPF registers with BFD when:
A neighbor finite state machine (FSM) transitions to full state.
•
Information About Bidirectional Forwarding Detection
Both OSPF BFD and BFD are enabled.
•
On broadcast interfaces, OSPF establishes a BFD session only with the designated router (DR) and backup
designated router (BDR), but not between any two routers in DROTHER state.
BFD Detection of Failures
Once a BFD session has been established and timer negations are complete, BFD peers send BFD control
packets that act in the same manner as an IGP hello protocol to detect liveliness, except at a more accelerated
rate. The following information should be noted:
BFD is a forwarding path failure detection protocol. BFD detects a failure, but the routing protocol must
•
take action to bypass a failed peer.
Starting Cisco IOS XE Denali 16.3.1, Cisco devices will support BFD version 0, where devices will use
•
one BFD session for multiple client protocols in the implementation. For example, if a network is running
OSPF and EIGRP across the same link to the same peer, only one BFD session will be established, and
BFD will share session information with both routing protocols.
BFD Version Interoperability
All BFD sessions come up as Version 1 by default and will be interoperable with Version 0. The system
automatically performs BFD version detection, and BFD sessions between neighbors will run in the highest
common BFD version between neighbors. For example, if one BFD neighbor is running BFD Version 0 and
the other BFD neighbor is running Version 1, the session will run BFD Version 0. The output from the show
bfd neighbors [details] command will verify which BFD version a BFD neighbor is running.
See the Example Configuring BFD in an EIGRP Network with Echo Mode Enabled by Default for an example
of BFD version detection.
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Information About Bidirectional Forwarding Detection
BFD Session Limits
Starting Cisco IOS XE Denali 16.3.1, the number of BFD sessions that can be created has been increased to
100.
BFD Support for Nonbroadcast Media Interfaces
Starting Cisco IOS XE Denali 16.3.1, the BFD feature is supported on routed, SVI and L3 portchannels.
The bfd interval command must be configured on the interface to initiate BFD monitoring.
BFD Support for Nonstop Forwarding with Stateful Switchover
Typically, when a networking device restarts, all routing peers of that device detect that the device went down
and then came back up. This transition results in a routing flap, which could spread across multiple routing
domains. Routing flaps caused by routing restarts create routing instabilities, which are detrimental to the
overall network performance. Nonstop forwarding (NSF) helps to suppress routing flaps in devices that are
enabled with stateful switchover (SSO), thereby reducing network instability.
NSF allows for the forwarding of data packets to continue along known routes while the routing protocol
information is being restored after a switchover. With NSF, peer networking devices do not experience routing
flaps. Data traffic is forwarded through intelligent line cards or dual forwarding processors while the standby
RP assumes control from the failed active RP during a switchover. The ability of line cards and forwarding
processors to remain up through a switchover and to be kept current with the Forwarding Information Base
(FIB) on the active RP is key to NSF operation.
In devices that support dual RPs, SSO establishes one of the RPs as the active processor; the other RP is
designated as the standby processor, and then synchronizes information between them. A switchover from
the active to the standby processor occurs when the active RP fails, when it is removed from the networking
device, or when it is manually taken down for maintenance.
Configuring Bidirectional Forwarding Detection
BFD Support for Stateful Switchover
The BFD protocol provides short-duration detection of failures in the path between adjacent forwarding
engines. In network deployments that use dual RP routers or switches (to provide redundancy), the routers
have a graceful restart mechanism that protects the forwarding state during a switchover between the active
RP and the standby RP.
The dual RPs have variable switchover times that depend on the ability of the hardware to detect a
communication failure. When BFD is running on the RP, some platforms are not able to detect a switchover
before the BFD protocol times out; these platforms are referred to as slow switchover platforms.
BFD Support for Static Routing
Unlike dynamic routing protocols, such as OSPF and BGP, static routing has no method of peer discovery.
Therefore, when BFD is configured, the reachability of the gateway is completely dependent on the state of
the BFD session to the specified neighbor. Unless the BFD session is up, the gateway for the static route is
considered unreachable, and therefore the affected routes will not be installed in the appropriate Routing
Information Base (RIB).
For a BFD session to be successfully established, BFD must be configured on the interface on the peer and
there must be a BFD client registered on the peer for the address of the BFD neighbor. When an interface is
used by dynamic routing protocols, the latter requirement is usually met by configuring the routing protocol
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Configuring Bidirectional Forwarding Detection
instances on each neighbor for BFD. When an interface is used exclusively for static routing, this requirement
must be met by configuring static routes on the peers.
If a BFD configuration is removed from the remote peer while the BFD session is in the up state, the updated
state of the BFD session is not signaled to IPv4 static. This will cause the static route to remain in the RIB.
The only workaround is to remove the IPv4 static BFD neighbor configuration so that the static route no
longer tracks BFD session state. Also, if you change the encapsulation type on a serial interface to one that
is unsupported by BFD, BFD will be in a down state on that interface. The workaround is to shut down the
interface, change to a supported encapsulation type, and then reconfigure BFD.
A single BFD session can be used by an IPv4 static client to track the reachability of next hops through a
specific interface. You can assign a BFD group for a set of BFD-tracked static routes. Each group must have
one active static BFD configuration, one or more passive BFD configurations, and the corresponding static
routes to be BFD-tracked. Nongroup entries are BFD-tracked static routes for which a BFD group is not
assigned. A BFD group must accommodate static BFD configurations that can be part of different VRFs.
Effectively, the passive static BFD configurations need not be in the same VRF as that of the active
configuration.
For each BFD group, there can be only one active static BFD session. You can configure the active BFD
session by adding a static BFD configuration and a corresponding static route that uses the BFD configuration.
The BFD session in a group is created only when there is an active static BFD configuration and the static
route that uses the static BFD configuration. When the active static BFD configuration or the active static
route is removed from a BFD group, all the passive static routes are withdrawn from the RIB. Effectively, all
the passive static routes are inactive until an active static BFD configuration and a static route to be tracked
by the active BFD session are configured in the group.
Similarly, for each BFD group, there can be one or more passive static BFD configurations and their
corresponding static routes to be BFD-tracked. Passive static session routes take effect only when the active
BFD session state is reachable. Though the active BFD session state of the group is reachable, the passive
static route is added to the RIB only if the corresponding interface state is up. When a passive BFD session
is removed from a group, it will not affect the active BFD session if one existed, or the BFD group reachability
status.
Information About Bidirectional Forwarding Detection
Benefits of Using BFD for Failure Detection
When you deploy any feature, it is important to consider all the alternatives and be aware of any trade-offs
being made.
The closest alternative to BFD in conventional EIGRP, IS-IS, and OSPF deployments is the use of modified
failure detection mechanisms for EIGRP, IS-IS, and OSPF routing protocols.
If you set EIGRP hello and hold timers to their absolute minimums, the failure detection rate for EIGRP falls
to within a one- to two-second range.
If you use fast hellos for either IS-IS or OSPF, these Interior Gateway Protocol (IGP) protocols reduce their
failure detection mechanisms to a minimum of one second.
There are several advantages to implementing BFD over reduced timer mechanisms for routing protocols:
Although reducing the EIGRP, IS-IS, and OSPF timers can result in minimum detection timer of one
•
to two seconds, BFD can provide failure detection in less than one second.
Because BFD is not tied to any particular routing protocol, it can be used as a generic and consistent
•
failure detection mechanism for EIGRP, IS-IS, and OSPF.
Because some parts of BFD can be distributed to the data plane, it can be less CPU-intensive than the
•
reduced EIGRP, IS-IS, and OSPF timers, which exist wholly at the control plane.
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Configuring Bidirectional Forwarding Detection
How to Configure Bidirectional Forwarding Detection
How to Configure Bidirectional Forwarding Detection
Configuring BFD Session Parameters on the Interface
To configure BFD on an interface, you need to set the baseline BFD session parameters on an interface. Repeat
the steps in this procedure for each interface over which you want to run BFD sessions to BFD neighbors.
Procedure
PurposeCommand or Action
Step 1
Step 2
Step 3
Example:
Device> enable
Example:
Device# configure terminal
ip address ipv4-address mask
•
ipv6 address ipv6-address/mask
•
Example:
Configuring an IPv4 address for the interface:
Device(config-if)# ip address
10.201.201.1 255.255.255.0
Configuring an IPv6 address for the interface:
Device(config-if)# ipv6 address
2001:db8:1:1::1/32
Enables privileged EXEC mode.enable
Enter your password if prompted.
•
Enters global configuration mode.configure terminal
Configures an IP address for the interface.Perform one of the following steps:
Step 4
bfd interval milliseconds min_rx milliseconds
multiplier interval-multiplier
Enables BFD on the interface.
The BFD interval configuration is removed when
the subinterface on which it is configured is
Example:
Device(config-if)# bfd interval 100
min_rx 100 multiplier 3
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removed.
The BFD interval configuration is not removed
when:
an IPv4 address is removed from an interface
•
an IPv6 address is removed from an interface
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IPv6 is disabled from an interface
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Configuring Bidirectional Forwarding Detection
How to Configure Bidirectional Forwarding Detection
PurposeCommand or Action
an interface is shutdown
•
IPv4 CEF is disabled globally or locally on
•
an interface
IPv6 CEF is disabled globally or locally on
•
an interface
Step 5
end
Example:
Device(config-if)# end
Configuring BFD Support for Dynamic Routing Protocols
Configuring BFD Support for eBGP
This section describes the procedure for configuring BFD support for BGP so that BGP is a registered protocol
with BFD and will receive forwarding path detection failure messages from BFD.
Before You Begin
e BGP must be running on all participating routers.
The baseline parameters for BFD sessions on the interfaces over which you want to run BFD sessions to BFD
neighbors must be configured. See the Configuring BFD Session Parameters on the Interface section for more
information.
Exits interface configuration mode and returns to
privileged EXEC mode.
Output from the show bfd neighbors details command shows the configured intervals.Note
Procedure
Step 1
Example:
Device> enable
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
PurposeCommand or Action
Enables privileged EXEC mode.enable
Enter your password if prompted.
•
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How to Configure Bidirectional Forwarding Detection
Configuring Bidirectional Forwarding Detection
PurposeCommand or Action
Step 2
Step 3
Step 4
Step 5
Step 6
Example:
Device# configure terminal
router bgp as-tag
Example:
Device(config)# router bgp tag1
neighbor ip-address fall-over bfd
Example:
Device(config-router)# neighbor
172.16.10.2 fall-over bfd
end
Example:
Device(config-router)# end
show bfd neighbors [details]
Example:
Enters global configuration mode.configure terminal
Specifies a BGP process and enters router
configuration mode.
Enables BFD support for fallover.
Exits router configuration mode and returns the
router to privileged EXEC mode.
(Optional) Verifies that the BFD neighbor is
active and displays the routing protocols that
BFD has registered.
Device# show bfd neighbors detail
Step 7
show ip bgp neighbor
Example:
Device# show ip bgp neighbor
Configuring BFD Support for EIGRP
This section describes the procedure for configuring BFD support for EIGRP so that EIGRP is a registered
protocol with BFD and will receive forwarding path detection failure messages from BFD. There are two
methods for enabling BFD support for EIGRP:
You can enable BFD for all of the interfaces for which EIGRP is routing by using the bfd all-interfaces
•
command in router configuration mode.
You can enable BFD for a subset of the interfaces for which EIGRP is routing by using the bfd interface
•
type number command in router configuration mode.
(Optional) Displays information about BGP and
TCP connections to neighbors.
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Configuring Bidirectional Forwarding Detection
Before You Begin
EIGRP must be running on all participating routers.
The baseline parameters for BFD sessions on the interfaces over which you want to run BFD sessions to BFD
neighbors must be configured. See the Configuring BFD Session Parameters on the Interface section for more
information.
Output from the show bfd neighbors details command shows the configured intervals.Note
Procedure
How to Configure Bidirectional Forwarding Detection
PurposeCommand or Action
Step 1
Step 2
Step 3
Step 4
Example:
Device> enable
Example:
Device# configure terminal
router eigrp as-number
Example:
Device(config)# router eigrp 123
Do one of the following:
bfd all-interfaces
•
bfd interface type number
•
Example:
Enables privileged EXEC mode.enable
Enter your password if prompted.
•
Enters global configuration mode.configure terminal
Configures the EIGRP routing process and enters
router configuration mode.
Enables BFD globally on all interfaces associated
with the EIGRP routing process.
or
Enables BFD on a per-interface basis for one or
more interfaces associated with the EIGRP routing
process.
Device(config-router)# bfd
all-interfaces
Example:
Device(config-router)# bfd interface
GigabitFastEthernet 1/0/1
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
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How to Configure Bidirectional Forwarding Detection
Configuring Bidirectional Forwarding Detection
PurposeCommand or Action
Step 5
Step 6
Step 7
end
Example:
Device(config-router) end
show bfd neighbors [details]
Example:
Device# show bfd neighbors details
show ip eigrp interfaces [type number]
[as-number] [detail]
Example:
Device# show ip eigrp interfaces
detail
Configuring BFD Support for IS-IS
This section describes the procedures for configuring BFD support for IS-IS so that IS-IS is a registered
protocol with BFD and will receive forwarding path detection failure messages from BFD. There are two
methods for enabling BFD support for IS-IS:
Exits router configuration mode and returns the
router to privileged EXEC mode.
(Optional) Verifies that the BFD neighbor is active
and displays the routing protocols that BFD has
registered.
(Optional) Displays the interfaces for which BFD
support for EIGRP has been enabled.
Prerequisites
Note
You can enable BFD for all of the interfaces on which IS-IS is supporting IPv4 routing by using the bfd
•
all-interfaces command in router configuration mode. You can then disable BFD for one or more of
those interfaces using the isis bfd disable command in interface configuration mode.
You can enable BFD for a subset of the interfaces for which IS-IS is routing by using the isis bfd
•
command in interface configuration mode.
To configure BFD support for IS-IS, perform the steps in one of the following sections:
IS-IS must be running on all participating routers.
The baseline parameters for BFD sessions on the interfaces that you want to run BFD sessions to BFD neighbors
over must be configured. See the Configuring BFD Session Parameters on the Interface section for more
information.
Output from the show bfd neighbors details command shows the configured intervals. The output does
not show intervals that were changed because hardware-offloaded BFD sessions were configured with
Tx and Rx intervals that are not multiples of 50 ms.
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Configuring Bidirectional Forwarding Detection
Configuring BFD Support for IS-IS for All Interfaces
To configure BFD on all IS-IS interfaces that support IPv4 routing, perform the steps in this section.
Procedure
How to Configure Bidirectional Forwarding Detection
PurposeCommand or Action
Step 1
Step 2
Step 3
Step 4
Step 5
Example:
Device> enable
Example:
Device# configure terminal
router isis area-tag
Example:
Device(config)# router isis tag1
bfd all-interfaces
Example:
Device(config-router)# bfd
all-interfaces
exit
Example:
Enables privileged EXEC mode.enable
Enter your password if prompted.
•
Enters global configuration mode.configure terminal
Specifies an IS-IS process and enters router
configuration mode.
Enables BFD globally on all interfaces associated with
the IS-IS routing process.
(Optional) Returns the router to global configuration
mode.
Step 6
Step 7
Device(config-router)# exit
interface type number
Example:
Device(config)# interface
fastethernet 6/0
ip router isis [ tag ]
Example:
Device(config-if)# ip router isis
tag1
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
(Optional) Enters interface configuration mode.
(Optional) Enables support for IPv4 routing on the
interface.
11
How to Configure Bidirectional Forwarding Detection
Configuring Bidirectional Forwarding Detection
PurposeCommand or Action
Step 8
Step 9
Step 10
Step 11
isis bfd [disable]
Example:
Device(config-if)# isis bfd
end
Example:
Device(config-if)# end
show bfd neighbors [details]
Example:
Device# show bfd neighbors details
show clns interface
Example:
Device# show clns interface
(Optional) Enables or disables BFD on a per-interface
basis for one or more interfaces associated with the
IS-IS routing process.
Note
You should use the disable keyword only if
you had earlier enabled BFD on all of the
interfaces that IS-IS is associated with, using
the bfd all-interfaces command in
configuration mode.
Exits interface configuration mode and returns the
router to privileged EXEC mode.
(Optional) Displays information that can be used to
verify if the BFD neighbor is active and displays the
routing protocols that BFD has registered.
(Optional) Displays information that can be used to
verify if BFD for IS-IS has been enabled for a specific
IS-IS interface that is associated.
Configuring BFD Support for IS-IS for One or More Interfaces
To configure BFD for only one or more IS-IS interfaces, perform the steps in this section.
Procedure
Step 1
Example:
Device> enable
Step 2
Example:
Device# configure terminal
PurposeCommand or Action
Enables privileged EXEC mode.enable
Enter your password if prompted.
•
Enters global configuration mode.configure terminal
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
12
Configuring Bidirectional Forwarding Detection
How to Configure Bidirectional Forwarding Detection
PurposeCommand or Action
Step 3
Step 4
Step 5
Step 6
interface type number
Example:
Device(config)# interface
fastethernet 6/0
ip router isis [ tag ]
Example:
Device(config-if)# ip router isis
tag1
isis bfd [disable]
Example:
Device(config-if)# isis bfd
end
Example:
Enters interface configuration mode.
Enables support for IPv4 routing on the interface.
Enables or disables BFD on a per-interface basis for
one or more interfaces associated with the IS-IS routing
process.
Note
You should use the disable keyword only if
you enabled BFD on all of the interfaces that
IS-IS is associated with using the bfd
all-interfaces command in router
configuration mode.
Exits interface configuration mode and returns the
router to privileged EXEC mode.
Device(config-if)# end
Step 7
show bfd neighbors [details]
Example:
Device# show bfd neighbors
details
Step 8
show clns interface
Example:
Device# show clns interface
Configuring BFD Support for OSPF
This section describes the procedures for configuring BFD support for OSPF so that OSPF is a registered
protocol with BFD and will receive forwarding path detection failure messages from BFD. You can either
configure BFD support for OSPF globally on all interfaces or configure it selectively on one or more interfaces.
There are two methods for enabling BFD support for OSPF:
(Optional) Displays information that can help verify if
the BFD neighbor is active and displays the routing
protocols that BFD has registered.
(Optional) Displays information that can help verify if
BFD for IS-IS has been enabled for a specific IS-IS
interface that is associated.
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
13
How to Configure Bidirectional Forwarding Detection
You can enable BFD for all of the interfaces for which OSPF is routing by using the bfd all-interfaces
•
command in router configuration mode. You can disable BFD support on individual interfaces using
the ip ospf bfd [disable] command in interface configuration mode.
You can enable BFD for a subset of the interfaces for which OSPF is routing by using the ip ospf bfd
•
command in interface configuration mode.
See the following sections for tasks for configuring BFD support for OSPF:
Configuring BFD Support for OSPF for All Interfaces
To configure BFD for all OSPF interfaces, perform the steps in this section.
If you do not want to configure BFD on all OSPF interfaces and would rather configure BFD support specifically
for one or more interfaces, see the Configuring BFD Support for OSPF for One or More Interfaces section.
Before You Begin
OSPF must be running on all participating routers.
The baseline parameters for BFD sessions on the interfaces over which you want to run BFD sessions to BFD
neighbors must be configured. See the Configuring BFD Session Parameters on the Interface section for more
information.
Configuring Bidirectional Forwarding Detection
Procedure
Step 1
Step 2
Step 3
Step 4
Example:
Device> enable
Example:
Device# configure terminal
router ospf process-id
Example:
Device(config)# router ospf 4
bfd all-interfaces
Example:
Device(config-router)# bfd
all-interfaces
PurposeCommand or Action
Enables privileged EXEC mode.enable
Enter your password if prompted.
•
Enters global configuration mode.configure terminal
Specifies an OSPF process and enters router
configuration mode.
Enables BFD globally on all interfaces associated with
the OSPF routing process.
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
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Configuring Bidirectional Forwarding Detection
How to Configure Bidirectional Forwarding Detection
PurposeCommand or Action
Step 5
Step 6
Step 7
Step 8
exit
Example:
Device(config-router)# exit
interface type number
Example:
Device(config)# interface
fastethernet 6/0
ip ospf bfd [disable]
Example:
Device(config-if)# ip ospf bfd
disable
end
Example:
Device(config-if)# end
(Optional) Returns the device to global configuration
mode. Enter this command only if you want to perform
Step 7 to disable BFD for one or more interfaces.
(Optional) Enters interface configuration mode. Enter
this command only if you want to perform Step 7 to
disable BFD for one or more interfaces.
(Optional) Disables BFD on a per-interface basis for one
or more interfaces associated with the OSPF routing
process.
Note
You should use the disable keyword only if you
enabled BFD on all of the interfaces that OSPF
is associated with using the bfd all-interfaces
command in router configuration mode.
Exits interface configuration mode and returns the router
to privileged EXEC mode.
Step 9
Step 10
show bfd neighbors [details]
Example:
Device# show bfd neighbors
detail
show ip ospf
Example:
Device# show ip ospf
Configuring BFD Support for OSPF for One or More Interfaces
To configure BFD on one or more OSPF interfaces, perform the steps in this section.
Before You Begin
OSPF must be running on all participating routers.
The baseline parameters for BFD sessions on the interfaces over which you want to run BFD sessions to BFD
neighbors must be configured. See the Configuring BFD Session Parameters on the Interface section for more
information.
(Optional) Displays information that can help verify if
the BFD neighbor is active and displays the routing
protocols that BFD has registered.
(Optional) Displays information that can help verify if
BFD for OSPF has been enabled.
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How to Configure Bidirectional Forwarding Detection
Procedure
Configuring Bidirectional Forwarding Detection
PurposeCommand or Action
Step 1
Step 2
Step 3
Step 4
Example:
Device> enable
Example:
Device# configure terminal
interface type number
Example:
Device(config)# interface
fastethernet 6/0
ip ospf bfd [disable]
Example:
Device(config-if)# ip ospf bfd
Enables privileged EXEC mode.enable
Enter your password if prompted.
•
Enters global configuration mode.configure terminal
Enters interface configuration mode.
Enables or disables BFD on a per-interface basis for one
or more interfaces associated with the OSPF routing
process.
Note
You should use the disable keyword only if
you enabled BFD on all of the interfaces that
OSPF is associated with using the bfd
all-interfaces command in router configuration
mode.
Step 5
Step 6
Step 7
end
Example:
Device(config-if)# end
show bfd neighbors [details]
Example:
Device# show bfd neighbors
details
show ip ospf
Example:
Device# show ip ospf
Exits interface configuration mode and returns the router
to privileged EXEC mode.
(Optional) Displays information that can help verify if
the BFD neighbor is active and displays the routing
protocols that BFD has registered.
(Optional) Displays information that can help verify if
BFD support for OSPF has been enabled.
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Configuring Bidirectional Forwarding Detection
Configuring BFD Support for HSRP
Perform this task to enable BFD support for Hot Standby Router Protocol (HSRP.) Repeat the steps in this
procedure for each interface over which you want to run BFD sessions to HSRP peers.
HSRP supports BFD by default. If HSRP support for BFD has been manually disabled, you can reenable it
at the router level to enable BFD support globally for all interfaces or on a per-interface basis at the interface
level.
Before You Begin
HSRP must be running on all participating routers.
•
Cisco Express Forwarding must be enabled.
•
Procedure
How to Configure Bidirectional Forwarding Detection
PurposeCommand or Action
Step 1
Step 2
Step 3
Step 4
Step 5
Example:
Device> enable
Example:
Device# configure terminal
ip cef [distributed]
Example:
Device(config)# ip cef
interface type number
Example:
Device(config)# interface FastEthernet
6/0
ip address ip-address mask
Enables privileged EXEC mode.enable
Enter your password if prompted.
•
Enters global configuration mode.configure terminal
Enables Cisco Express Forwarding or
distributed Cisco Express Forwarding.
Enters interface configuration mode.
Configures an IP address for the interface.
Step 6
Example:
Device(config-if)# ip address 10.1.0.22
255.255.0.0
standby [group-number] ip [ip-address
[secondary]]
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
Activates HSRP.
17
How to Configure Bidirectional Forwarding Detection
Example:
Device(config-if)# standby 1 ip 10.0.0.11
Configuring Bidirectional Forwarding Detection
PurposeCommand or Action
Step 7
Step 8
Step 9
Step 10
Step 11
standby bfd
Example:
Device(config-if)# standby bfd
Example:
Device(config-if)# exit
standby bfd all-interfaces
Example:
Device(config)# standby bfd
all-interfaces
Example:
Device(config)# exit
show standby neighbors
Example:
(Optional) Enables HSRP support for BFD
on the interface.
Exits interface configuration mode.exit
(Optional) Enables HSRP support for BFD
on all interfaces.
Exits global configuration mode.exit
(Optional) Displays information about
HSRP support for BFD.
Device# show standby neighbors
Configuring BFD Support for Static Routing
Perform this task to configure BFD support for static routing. Repeat the steps in this procedure on each BFD
neighbor. For more information, see the "Example: Configuring BFD Support for Static Routing" section.
Procedure
Step 1
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PurposeCommand or Action
Enables privileged EXEC mode.enable
Configuring Bidirectional Forwarding Detection
Example:
Device> enable
How to Configure Bidirectional Forwarding Detection
PurposeCommand or Action
Enter your password if prompted.
•
Step 2
Step 3
Step 4
Example:
Device# configure terminal
interface type number
Example:
Device(config)# interface serial 2/0
ip address ipv4-address mask
•
ipv6 address ipv6-address/mask
•
Example:
Configuring an IPv4 address for the interface:
Device(config-if)# ip address
10.201.201.1 255.255.255.0
Configuring an IPv6 address for the interface:
Device(config-if)# ipv6 address
2001:db8:1:1::1/32
Enters global configuration mode.configure terminal
Configures an interface and enters interface
configuration mode.
Configures an IP address for the interface.Perform one of the following steps:
Step 5
bfd interval milliseconds mix_rx milliseconds
multiplier interval-multiplier
Example:
Device(config-if)# bfd interval 500
min_rx 500 multiplier 5
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
Enables BFD on the interface.
The bfd interval configuration is removed when
the subinterface on which it is configured is
removed.
The bfd interval configuration is not removed
when:
an IPv4 address is removed from an
•
interface
an IPv6 address is removed from an
•
interface
IPv6 is disabled from an interface
•
an interface is shutdown
•
IPv4 CEF is disabled globally or locally on
•
an interface
19
How to Configure Bidirectional Forwarding Detection
Configuring Bidirectional Forwarding Detection
PurposeCommand or Action
IPv6 CEF is disabled globally or locally on
•
an interface
Step 6
Step 7
Step 8
Step 9
exit
Example:
Device(config-if)# exit
ip route static bfd interface-type
interface-number ip-address [group
group-name [passive]]
Example:
Device(config)# ip route static bfd
TenGigabitEthernet1/0/1 10.10.10.2 group
group1 passive
ip route [vrf vrf-name] prefix mask {ip-address
| interface-type interface-number [ip-address]}
[dhcp] [distance] [name next-hop-name]
[permanent | track number] [tag tag]
Example:
Device(config)# ip route 10.0.0.0
255.0.0.0
exit
Example:
Exits interface configuration mode and returns
to global configuration mode.
Specifies a static route BFD neighbor.
The interface-type, interface-number, and
•
ip-address arguments are required because
BFD support exists only for directly
connected neighbors.
Specifies a static route BFD neighbor.
Exits global configuration mode and returns to
privileged EXEC mode.
Device(config)# exit
Step 10
show ip static route
(Optional) Displays static route database
information.
Example:
Device# show ip static route
Step 11
show ip static route bfd
(Optional) Displays information about the static
BFD configuration from the configured BFD
groups and nongroup entries.
Exits privileged EXEC mode and returns to user
Step 12
Example:
Device# show ip static route bfd
exit
EXEC mode.
Example:
Device# exit
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