Foundry Configuration Guide for the FESX, FSX, and FWSX
21 - 58 © Foundry Networks, Inc. December 2005
To display the cooperative filtering configuration on the Layer 3 Switch, enter a command such as the following.
The line shown in bold type shows the cooperative filtering status.
Syntax: show ip bgp neighbor <ip-addr>
To display the ORFs received from a neighbor, enter a command such as the following:
Syntax: show ip bgp neighbor <ip-addr> received prefix-filter
Configuring Route Flap Dampening
A “route flap” is the change in a route’s state, from up to down or down to up. When a route’s state changes, the
state change causes changes in the route tables of the routers that support the route. Frequent changes in a
route’s state can cause Internet instability and add processing overhead to the routers that support the route.
Route flap dampening is a mechanism that reduces the impact of route flap by changing a BGP4 router’s
response to route state changes. When route flap dampening is configured, the Layer 3 Switch suppresses
unstable routes until the route’s state changes reduce enough to meet an acceptable degree of stability. The
Foundry implementation of route flap dampening is based on RFC 2439.
Route flap dampening is disabled by default. You can enable the feature globally or on an individual route basis
using route maps.
NOTE: The Layer 3 Switch applies route flap dampening only to routes learned from EBGP neighbors.
The route flap dampening mechanism is based on penalties. When a route exceeds a configured penalty value,
the Layer 3 Switch stops using that route and also stops advertising it to other routers. The mechanism also
FESX424 Router# show ip bgp neighbor 10.10.10.1
1 IP Address: 10.10.10.1, AS: 65200 (IBGP), RouterID: 10.10.10.1
State: ESTABLISHED, Time: 0h0m7s, KeepAliveTime: 60, HoldTime: 180
RefreshCapability: Received
CooperativeFilteringCapability: Received
Messages: Open Update KeepAlive Notification Refresh-Req
Sent : 1 0 1 0 1
Received: 1 0 1 0 1
Last Update Time: NLRI Withdraw NLRI Withdraw
Tx: --- --- Rx: --- ---
Last Connection Reset Reason:Unknown
Notification Sent: Unspecified
Notification Received: Unspecified
TCP Connection state: ESTABLISHED
Byte Sent: 110, Received: 110
Local host: 10.10.10.2, Local Port: 8138
Remote host: 10.10.10.1, Remote Port: 179
ISentSeq: 460 SendNext: 571 TotUnAck: 0
TotSent: 111 ReTrans: 0 UnAckSeq: 571
IRcvSeq: 7349 RcvNext: 7460 SendWnd: 16384
TotalRcv: 111 DupliRcv: 0 RcvWnd: 16384
SendQue: 0 RcvQue: 0 CngstWnd: 5325
FESX424 Router# show ip bgp neighbor 10.10.10.1 received prefix-filter
ip prefix-list 10.10.10.1: 4 entries
seq 5 permit 10.10.0.0/16 ge 18 le 28
seq 10 permit 20.20.10.0/24
seq 15 permit 30.0.0.0/8 le 32
seq 20 permit 40.10.0.0/16 ge 18
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