Cisco ME-3600X-24CX Series Switch Chassis Configuration Guide, Release 15.4(3)S

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Book Title

Cisco ME-3600X-24CX Series Switch Chassis Configuration Guide, Release 15.4(3)S

Chapter Title

BFD Multihop Support for IPv4 Static Routes

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Updated:
August 19, 2014

Chapter: BFD Multihop Support for IPv4 Static Routes

BFD Multihop Support for IPv4 Static Routes

First Published: July 16, 2014

 

The BFD Multihop Support for IPv4 Static Routes feature enables detection of IPv4 network failure between paths that are not directly connected. If a Bidirectional Forwarding Detection (BFD) session is up (that is, the next-hop destination is reachable), IPv4 static routes that are associated with IPv4 static BFD configuration are added to a routing table. If the BFD session is down, the routing table removes all associated static routes from the routing table.

This feature is applicable on different kinds of interfaces such as physical, subinterface, and virtual tunnels and across intra-area and inter area topologies.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see 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 for BFD Multihop Support for IPv4 Static Routes” section.

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.

Contents

Prerequisites for BFD Multihop Support for IPv4 Static Routes

  • The BFD destination for which an IPv4 static route has to be configured must be reachable by all devices.
  • The configured device must have at least one static route with the next-hop destination as a BFD destination for an associated session. If not, the BFD session is not created on the device.

Information About BFD Multihop Support for IPv4 Static Routes

BFDv4 Associated Mode

In Bidirectional Forwarding Detection for IPv4 (BFDv4) associated mode, an IPv4 static route is automatically associated with an IPv4 static BFDv4 multihop destination address if the static route next hop exactly matches the static BFDv4 multihop destination address.

The state of the BFDv4 session is used to determine whether the associated IPv4 static routes are added in the IPv4 routing information base (RIB). For example, static routes are added in the IPv4 RIB only if the BFDv4 multihop destination is reachable, and the static routes are removed from the IPv4 RIB if the BFDv4 multihop destination subsequently becomes unreachable.

BFDv4 Unassociated Mode

In Bidirectional Forwarding Detection for IPv4 (BFDv4), an IPv4 static BFD multihop destination can be configured in unassociated mode. In unassociate mode, a BFD neighbor is not associated with a static route, and the BFD sessions are requested if the IPv4 static BFD is configured.

Unassociated mode is useful in the following scenario:

  • Absence of an IPv4 static route—This scenario occurs when a static route is on device A, and device B is the next hop. In associated mode, you must create both a static BFD multihop destination address and a static route on both devices to bring up the BFDv4 session from device B to device A. Specifying the static BFD multihop destination in unassociated mode on device B avoids the need to configure an unwanted static route.

How to Configure BFD Multihop Support for IPv4 Static Routes

Configuring BFD Multihop IPv4 Static Routes

Prerequisites

  • Specify a BFD destination address which is same as the IPv4 static route next hop or gateway address.
  • Configure a BFD map and a BFD multihop template for an interface on the device. The destination address and source address configured for a BFD map must match the BFD static multihop configuration and the source address must be a valid IP address configured for an interface in the routing table.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip route prefix mask ip-address

4. ip route static bfd multihop-destination-address multihop-source-address

5. ip route static bfd multihop-destination-address multihop-source-address unassociate

6. end

DETAILED STEPS

Command or Action
Purpose

Step 1

enable

 

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

 

Device# configure terminal

Enters global configuration mode.

Step 3

ip route prefix mask ip-address

 

Device(config)# ip route 192.0.2.0 255.255.255.0 10.1.1.2

Configures an IPv4 static route that BFD multihop uses to monitor static routes.

Step 4

ip route static bfd multihop-destination-address multihop-source-address

 

Device(config)# ip route static bfd 192.0.2.1 10.1.1.1

Configures the static IPv4 BFD multihop to be associated with a static IPv4 route.

Step 5

ip route static bfd multihop-destination-address multihop-source-address unassociate

 

Device(config)# ip route static bfd 192.0.2.1 10.1.1.1 unassociate

(Optional) Configures the static IPv4 BFD multihop to be associated with a static IPv4 route in unassociated mode.

Step 6

end

 

Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Verifying BFD Multihop Support for IPv4 Static Routes

The following show commands can be used to verify IPv4 static routes for BFD multihop:

  • show bfd neighbors— Displays a line-by-line listing of existing BFD adjacencies.
  • show ip static route bfd— Displays information about the IPv4 static BFD configured parameters.

Examples

Sample output for the show bfd neighbors command

Device#show bfd neighbors
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
50.1.1.1 1/1 Up Up

Sample output for the show bfd neighbors details command

Device#show bfd neighbors details
 
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
50.1.1.1 1/1 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 60.1.1.1
Handle: 1
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 50000, MinRxInt: 50000, Multiplier: 5
Received MinRxInt: 50000, Received Multiplier: 5
Holddown (hits): 206(0), Hello (hits): 50(3811)
Rx Count: 3319, Rx Interval (ms) min/max/avg: 1/64/47 last: 44 ms ago
Tx Count: 3291, Tx Interval (ms) min/max/avg: 1/56/47 last: 36 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: IPv4 Static
Map information:
Destination[vrf]: 50.1.1.1/32
Source[vrf]: 60.1.1.1/32
Template: 50ms
Authentication(Type/Keychain): invalid_type/
Uptime: 00:02:35
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 5 - Length: 24
My Discr.: 1 - Your Discr.: 1
Min tx interval: 50000 - Min rx interval: 50000
Min Echo interval: 0

Sample output for the show ip static route bfd command

Device#show ip static route bfd
Codes in []: R - Reachable, U - Unreachable, L - Loop, D - Not Tracked
IPV4 Static BFD Multihop Sessions:
Destination [vrf] : 50.1.1.1
Source [vrf] : 60.1.1.1
Status : [R]
Group Info :

Configuration Examples for BFD Multihop Support for IPv4 Static Routes

Example: Configuring BFD Multihop for IPv4 Static Routes in Associated Mode

Device> enable
Device# configure terminal
Device(config)# bfd map ipv4 192.0.2.1/32 10.1.1.1/32 test
Device(config)# bfd-template multi-hop test
Device(config-bfd)# interval min-tx 51 min-rx 51 multiplier 3
Device(config-bfd)# exit
Device(config)#ip route 172.1.1.0 255.255.255.0 192.0.2.1
Device(config)# ip route 192.0.2.0 255.255.255.0 10.1.1.2
Device(config)# interface GigabitEthernet 1/1
Device(config-if)# ip address 10.1.1.1 255.255.0.0
Device(config-if)# exit
Device(config)# ip route static bfd 192.0.2.1 10.1.1.1
Device(config)# end

Example: Configuring IPv4 Static Multihop for BFD in Unassociated Mode

Device> enable
Device# configure terminal
Device(config)# bfd map ipv4 192.0.2.1/32 10.1.1.1/32 test
Device(config)# bfd-template multi-hop test
Device(config-bfd)# interval min-tx 51 min-rx 51 multiplier 3
Device(config-bfd)# exit
Device(config)# ip route 192.0.2.0 255.255.255.0 10.1.1.2
Device(config)# interface GigabitEthernet 1/1
Device(config-if)# ip address 10.1.1.1 255.255.0.0
Device(config-if)# exit
Device(config)# ip route static bfd 192.0.2.1 10.1.1.1 unassociate
Device(config)# end

Additional References

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

IP Routing: Protocol Independent commands

IP Routing Protocol-Independent Command Reference

Standards

Standard
Title

—

—

MIBs

MIB
MIBs Link
  • —

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFC
Title

RFC 5883

BFD for Multihop Paths

Technical Assistance

Description
Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for BFD Multihop Support for IPv4 Static Routes

Table 6-1 lists the release history for this feature.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 6-1 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

 

Table 6-1 Feature Information for BFD Multihop Support for IPv4 Static Routes

Feature Name
Releases
Feature Information

BFD Multihop Support for IPv4 Static Routes

Cisco IOS XE 3.13.0S

The BFD Multihop Support for IPv4 Static Routes feature enables detection of IPv4 network failure between paths that are not directly connected. If a Bidirectional Forwarding Detection (BFD) session is up (that is, the next-hop destination is reachable), IPv4 static routes that are associated with IPv4 static BFD configuration are added to a routing table. If the BFD session is down, the routing table removes all associated static routes from the routing table.

The following commands were introduced or modified: ip route static bfd and show ip static route bfd.

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

© 2014 Cisco Systems, Inc. All rights reserved.

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