From: Georg Pauwen (pauwen@hotmail.com)
Date: Mon Jun 07 2004 - 05:25:41 GMT-3
Hello Sergio,
there is a bug in certain IOS versions whereby dampened bgp routes may be
incorrectly unsuppressed. Which IOS are you running ?
This bug appears in lab siutations, here are the release notes:
If a router is running BGP (Border Gateway Protocol) and configured for BGP
dampening, dampened routes may be unsuppressed too early.
The dampening function is operational and with default settings there is
little
operational impact. However timed repetion of flapping in a lab scenario
shows we might unsuppress routes before reaching the lowest threshold for
the penalty. Namely if a path is suppressed and value of penalty is higher
than reuse value but lower that suppress penalty, and the path flaps again,
it may lead to this situation.
There is no known workaround.
Check this link (if you have a CCO login):
Regards,
GP
>From: "Sergio Jimenez Arguedas" <sejimenez@its.co.cr>
>Reply-To: "Sergio Jimenez Arguedas" <sejimenez@its.co.cr>
>To: <ccielab@groupstudy.com>
>Subject: BGP ROUTE-DAMPENING!!!
>Date: Sun, 6 Jun 2004 15:56:29 -0600
>
>Hi Group,
>
>I am doing a LAB with Route-dampening in BGP, the problem is the following:
>
>
>R1 receives the toute 192.168.88.0 255.255.255.0 but It is dampening, so I
>applied a route-map DAMPENING in R1.
>
>
>________________________________________________
>
>R1#sh ip bgp 192.168.88.0 255.255.255.0
>BGP routing table entry for 192.168.88.0/24, version 59
>Paths: (1 available, no best path)
>Flag: 0x208
> Not advertised to any peer
> 64600 (history entry)
> 172.16.20.5 (metric 65) from 172.16.20.5 (172.16.20.5)
> Origin IGP, metric 0, localpref 100, external
> Dampinfo: penalty 2804, flapped 3 times in 00:03:09
>
>________________________________________________
>
>
>R1#sh route-map
>route-map DAMPENING, permit, sequence 10
> Match clauses:
> ip address (access-lists): 10
> Set clauses:
> dampening 15 750 1500 60
> Policy routing matches: 0 packets, 0 bytes
>route-map DAMPENING, permit, sequence 20
> Match clauses:
> Set clauses:
> Policy routing matches: 0 packets, 0 bytes
>
>________________________________________________________________
>R1#sh ip bgp flap-statistics
>BGP table version is 59, local router ID is 172.16.10.1
>Status codes: s suppressed, d damped, h history, * valid, > best, i -
>internal
>Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network From Flaps Duration Reuse Path
> h 192.168.88.0 172.16.20.5 3 00:10:07 64600
>_________________________________________________________________
>
>
>
>
>The penalty is 2804 but the route isn4t suppress of the BGP routing table:
>
>It shows the "h" and not the "d", Also the sh ip bgp 192.168.88.0
>255.255.255.0 doesn4t show the reuse in XXXX time...
>
>
>So I really don4t know What is happening!!!
>
>
>Rgds,
>
>
>Sergio
>
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This archive was generated by hypermail 2.1.4 : Sat Jul 03 2004 - 19:40:34 GMT-3