Cisco Catalyst 3560-X Series, Software Configuration Manual

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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 1 Configuring IP Unicast Routing
Configuring EIGRP
EIGRP NSF Capability
Beginning with Cisco IOS Release 12.2(58)SE, the IP services feature set supports EIGRP Cisco NSF
routing to speed up convergence and to eliminate traffic loss after a stack master change. For details
about this NSF capability, see the “Configuring Nonstop Forwarding” chapter in the
High Availability
Configuration Guide, Cisco IOS XE Release 3S .
The IP-services feature set also supports EIGRP NSF-capable routing for IPv4 for better convergence
and lower traffic loss following a stack master change. When an EIGRP NSF-capable stack master
restarts or a new stack master starts up and NSF restarts, the switch has no neighbors, and the topology
table is empty. The switch must bring up the interfaces, reacquire neighbors, and rebuild the topology
and routing tables without interrupting the traffic directed toward the switch stack. EIGRP peer routers
maintain the routes learned from the new stack master and continue forwarding traffic through the NSF
restart process.
To prevent an adjacency reset by the neighbors, the new stack master uses a new Restart (RS) bit in the
EIGRP packet header to show the restart. When the neighbor receives this, it synchronizes the stack in
its peer list and maintains the adjacency with the stack. The neighbor then sends its topology table to the
stack master with the RS bit set to show that it is NSF-aware and is aiding the new stack master.
If at least one of the stack peer neighbors is NSF-aware, the stack master receives updates and rebuilds
its database. Each NSF-aware neighbor sends an end of table (EOT) marker in the last update packet to
mark the end of the table content. The stack master recognizes the convergence when it receives the EOT
marker, and it then begins sending updates. When the stack master has received all EOT markers from
its neighbors or when the NSF converge timer expires, EIGRP notifies the routing information database
(RIB) of convergence and floods its topology table to all NSF-aware peers.
Note NSF is not supported on interfaces configured for Hot Standby Router Protocol (HSRP).
Use the nsf EIGRP routing configuration command to enable EIGRP NSF routing. Use the show ip
protocols privileged EXEC command to verify that NSF is enabled on the device. See the command
reference for this release for information about the nsf command.
Configuring Basic EIGRP Parameters
Beginning in privileged EXEC mode, follow these steps to configure EIGRP. Configuring the routing
process is required; other steps are optional:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2 router eigrp autonomous-system Enable an EIGRP routing process, and enter router configuration
mode. The AS number identifies the routes to other EIGRP routers
and is used to tag routing information.
Step 3 nsf (Optional) Enable EIGRP NSF. Enter this command on the stack
master and on all of its peers.
Step 4
network network-number Associate networks with an EIGRP routing process. EIGRP sends
updates to the interfaces in the specified networks.
Step 5
eigrp log-neighbor-changes (Optional) Enable logging of EIGRP neighbor changes to monitor
routing system stability.