Concept Guide

The following example shows how to congure values to reuse or restart a route. In the following example, default = 15 is the set time
before the value decrements, bgp dampening 2 ? is the set re-advertise value, bgp dampening 2 2000 ? is the suppress value,
and
bgp dampening 2 2000 3000 ? is the time to suppress a route. Default values are also shown.
DellEMC(conf-router_bgp)#bgp dampening ?
<1-45> Half-life time for the penalty (
default = 15)
route-map Route-map to specify criteria for dampening
<cr>
DellEMC(conf-router_bgp)#bgp dampening 2 ?
<1-20000> Value to start reusing a route (default = 750)
DellEMC(conf-router_bgp)#bgp dampening 2 2000 ?
<1-20000> Value to start suppressing a route (default = 2000)
DellEMC(conf-router_bgp)#
bgp dampening 2 2000 3000 ?
<1-255> Maximum duration to suppress a stable route (default = 60)
DellEMC(conf-router_bgp)#bgp dampening 2 2000 3000 10 ?
route-map Route-map to specify criteria for dampening
<cr>
To view a count of dampened routes, history routes, and penalized routes when you enable route dampening, look at the seventh line of the
show ip bgp summary command output, as shown in the following example (bold).
DellEMC>show ip bgp summary
BGP router identifier 10.114.8.131, local AS number 65515
BGP table version is 855562, main routing table version 780266
122836 network entrie(s) and 221664 paths using 29697640 bytes of memory
34298 BGP path attribute entrie(s) using 1920688 bytes of memory
29577 BGP AS-PATH entrie(s) using 1384403 bytes of memory
184 BGP community entrie(s) using 7616 bytes of memory
Dampening enabled. 0 history paths, 0 dampened paths, 0 penalized paths
Neighbor AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.114.8.34 18508 82883 79977 780266 0 2 00:38:51 118904
10.114.8.33 18508 117265 25069 780266 0 20 00:38:50 102759
DellEMC>
To view which routes are dampened (non-active), use the show ip bgp dampened-routes command in EXEC Privilege mode.
Changing BGP keepalive and hold timers
BGP uses timers to control the activity of sending the keepalive messages to its neighbors or peers. Also, you can adjust the interval of
how long the device has to wait for a keepalive messge from a neighbor before declaring the peer dead. To congure BGP timers, use
either or both of the following commands.
To change the BGP timers for all neighbors, use timers bgp command. To change the BGP keepalive and holdtime timers for a specic
neighbor or peer, use the
neighbor timers command.
NOTE
: Timer values congured with the neighbor timers command override the timer values congured with the timers
bgp command.
When two neighbors, congured with dierent keepalive and holdtime values, negotiate for new values, the resulting values are as
follows:
• the lower of the holdtime values is the new holdtime value, and
• whichever is the lower value; one-third of the new holdtime value, or the congured keepalive value is the new keepalive
value.
• Congure timer values for a BGP neighbor or peer group.
CONFIG-ROUTER-BGP mode
neighbors {ip-address | ipv6-address | peer-group-name} timers keepalive holdtime
– keepalive: Time interval, in seconds, between keepalive messages sent to the neighbor routers. The range is from 1 to 65535.
The default is 60 seconds.
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Border Gateway Protocol (BGP)