Administrator Guide

bgp cluster-id cluster-id
You can have multiple clusters in an AS.
• Congure the local router as a route reector and the neighbor or peer group identied is the route reector client.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | ipv6-address | peer-group-name} route-reflector-client
When you enable a route reector, Dell EMC Networking OS automatically enables route reection to all clients. To disable route reection
between all clients in this reector, use the no bgp client-to-client reflection command in CONFIGURATION ROUTER BGP
mode. All clients must be fully meshed before you disable route reection.
To view a route reector conguration, use the show config command in CONFIGURATION ROUTER BGP mode or the show
running-config bgp in EXEC Privilege mode.
Enabling Route Flap Dampening
When EBGP routes become unavailable, they “ap” and the router issues both WITHDRAWN and UPDATE notices.
A ap is when a route:
• is withdrawn
• is readvertised after being withdrawn
• has an attribute change
The constant router reaction to the WITHDRAWN and UPDATE notices causes instability in the BGP process. To minimize this instability,
you may congure penalties (a numeric value) for routes that ap. When that penalty value reaches a congured limit, the route is not
advertised, even if the route is up. In Dell EMC Networking OS, that penalty value is 1024. As time passes and the route does not ap, the
penalty value decrements or is decayed. However, if the route aps again, it is assigned another penalty.
The penalty value is cumulative and penalty is added under following cases:
• Withdraw
• Readvertise
• Attribute change
When dampening is applied to a route, its path is described by one of the following terms:
• history entry — an entry that stores information on a downed route
• dampened path — a path that is no longer advertised
• penalized path — a path that is assigned a penalty
To congure route ap dampening parameters, set dampening parameters using a route map, clear information on route dampening and
return suppressed routes to active state, view statistics on route apping, or change the path selection from the default mode
(deterministic) to non-deterministic, use the following commands.
• Enable route dampening.
CONFIG-ROUTER-BGP mode
bgp dampening [half-life | reuse | suppress max-suppress-time] [route-map map-name]
Enter the following optional parameters to congure route dampening parameters:
– half-life: the range is from 1 to 45. Number of minutes after which the Penalty is decreased. After the router assigns a Penalty
of 1024 to a route, the Penalty is decreased by half after the half-life period expires. The default is
15 minutes.
– reuse: the range is from 1 to 20000. This number is compared to the apping route’s Penalty value. If the Penalty value is less than
the reuse value, the apping route is once again advertised (or no longer suppressed). Withdrawn routes are removed from history
state. The default is 750.
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Border Gateway Protocol (BGP)