[c-nsp] BGP Hold Time Expired, but why?
Christian Koch
christian at broknrobot.com
Mon Jul 21 20:58:30 EDT 2008
same issue, no differences...got me
On Sun, Jul 20, 2008 at 2:53 AM, Oliver Boehmer (oboehmer) <
oboehmer at cisco.com> wrote:
> I don't know, but I would try it.. Looks weird..
>
> oli
>
> ------------------------------
> *From:* Christian Koch [mailto:christian at broknrobot.com]
> *Sent:* Saturday, July 19, 2008 7:07 PM
>
> *To:* Oliver Boehmer (oboehmer)
> *Cc:* cisco-nsp
> *Subject:* Re: [c-nsp] BGP Hold Time Expired, but why?
>
> config look ok as far as i can see, i actually dont have bgp router-id
> set in the bgp config... you think if i add that with the loopback ip, it
> would make a difference?
>
>
> config
>
> router bgp 65000
> no synchronization
> bgp log-neighbor-changes
> bgp graceful-restart restart-time 120
> bgp graceful-restart stalepath-time 360
> bgp graceful-restart
> bgp dampening
> neighbor Backbone peer-group
> neighbor Backbone remote-as 65000
> neighbor Backbone update-source Loopback1
> neighbor Backbone version 4
> neighbor Backbone send-community
> neighbor 10.10.10.2 peer-group Backbone
> neighbor 10.10.10.3 peer-group Backbone
> no auto-summary
>
>
>
>
>
> On Sat, Jul 19, 2008 at 12:29 PM, Oliver Boehmer (oboehmer) <
> oboehmer at cisco.com> wrote:
>
>> Hmm, "%BGP-5-ADJCHANGE: neighbor 10.10.10.3 Down BGP protocol
>> initialization" looks unexpected, not sure what's happening..
>> just a hunch, but can you double-check your config regarding loopback
>> addresses, bgp router-id and things? Possibly add some bgp debug (deb
>> bgp all events, deb bgp all, deb bgp all keep) and see if something
>> weird pops up?
>> What does the neighbor's (10.10.10.3) log say?
>>
>> oli
>>
>> ________________________________
>>
>> From: Christian Koch [mailto:christian at broknrobot.com]
>> Sent: Saturday, July 19, 2008 3:08 PM
>> To: Oliver Boehmer (oboehmer)
>> Cc: cisco-nsp
>> Subject: Re: [c-nsp] BGP Hold Time Expired, but why?
>>
>>
>> hmm, i didnt check cef/mpls on the new path, i should try that.. there
>> is connectivity between the loopbacks
>>
>> the session comes back up right after the timer expires.thats what
>> puzzles me
>>
>> actually 3-4 is about how long i kept it down for..
>>
>>
>> Jul 16 14:29:22 EDT: %LINK-3-UPDOWN: Interface TenGigabitEthernet2/2,
>> changed state to down
>> Jul 16 14:29:22 EDT: %LINEPROTO-SP-5-UPDOWN: Line protocol on Interface
>> TenGigabitEthernet2/2, changed state to down
>> Jul 16 14:29:22 EDT: %OSPF-5-ADJCHG: Process 10, Nbr 10.10.10.2 on
>> TenGigabitEthernet2/2 from FULL to DOWN, Neighbor Down: Interface down
>> or detached
>> Jul 16 14:29:22 EDT: %LDP-5-NBRCHG: LDP Neighbor 10.10.10.2:0 (11) is
>> DOWN (Interface not operational)
>> Jul 16 14:29:22 EDT: %LINK-SP-3-UPDOWN: Interface TenGigabitEthernet2/2,
>> changed state to down
>> Jul 16 14:29:23 EDT: %LINK-SP-3-UPDOWN: Interface TenGigabitEthernet2/2,
>> changed state to up
>> Jul 16 14:29:23 EDT: %LINK-3-UPDOWN: Interface TenGigabitEthernet2/2,
>> changed state to up
>> Jul 16 14:29:23 EDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface
>> TenGigabitEthernet2/2, changed state to up
>> Jul 16 14:29:23 EDT: %LINEPROTO-SP-5-UPDOWN: Line protocol on Interface
>> TenGigabitEthernet2/2, changed state to up
>> Jul 16 14:29:33 EDT: %LDP-5-NBRCHG: LDP Neighbor 10.10.10.2:0 (11) is UP
>> Jul 16 14:30:19 EDT: %OSPF-5-ADJCHG: Process 10, Nbr 10.10.10.2 on
>> TenGigabitEthernet2/2 from LOADING to FULL, Loading Done
>> Jul 16 14:30:37 EDT: %LDP-5-NBRCHG: LDP Neighbor 10.10.10.2:0 (4) is
>> DOWN (Discovery Hello Hold Timer expired)
>> Jul 16 14:31:39 EDT: %LDP-5-NBRCHG: LDP Neighbor 10.10.10.2:0 (4) is UP
>> Jul 16 14:32:38 EDT: %BGP-3-NOTIFICATION: received from neighbor
>> 10.10.10.3 4/0 (hold time expired) 0 bytes
>> Jul 16 14:32:38 EDT: %BGP-5-ADJCHANGE: neighbor 10.10.10.3 Down BGP
>> protocol initialization
>> Jul 16 14:32:45 EDT: %BGP-5-ADJCHANGE: neighbor 10.10.10.3 Up
>>
>>
>>
>> On Sat, Jul 19, 2008 at 3:24 AM, Oliver Boehmer (oboehmer)
>> <oboehmer at cisco.com> wrote:
>>
>>
>> No clue what's happening.. I've seen issues in the past with TCP
>> PMTUD
>> when the path converges over a link with a different MTU (which
>> is
>> happening in your case), but as BGP will not send packets larger
>> than
>> 4k, this shouldn't be an issue here.
>>
>> How long did you take down the link before bringing it back up?
>> I assume
>> longer than 3 minutes? Have you checked CEF and MPLS along the
>> new path?
>> You have IP connectivity between the loopbacks aR1 and bR2? Does
>> the
>> session come back up eventually, or will it stay down?
>>
>> oli
>>
>> Christian Koch <> wrote on Saturday, July 19, 2008 8:38 AM:
>>
>>
>> > sorry forgot to specify
>> >
>> > the bgp session from aR1 to bR2 is the session in question
>> >
>> > ck
>> >
>> > On Sat, Jul 19, 2008 at 2:21 AM, Christian Koch
>> > <christian at broknrobot.com> wrote:
>> >
>> >> Hello -
>> >>
>> >> I have the following topology in lab, testing different
>> failure
>> >> scenarios. When i disconnect the link between aR1 and bR1,
>> what
>> >> would appear to be normal happens - ospf and ldp neighbor go
>> down.
>> >>
>> >> When i re-connect the link between aR1 and bR1, the interface
>> comes
>> >> back up, osfp/ldp neighbor is re-established.
>> >>
>> >> 3minutes later, bgp holdtime expires , and all links are up..
>> >>
>> >> aR1-----------------bR1
>> >>> |
>> >>> |
>> >>> |
>> >>> | aR2-----------------bR2
>> >>
>> >>
>> >> Some Notes
>> >> - All Links 10GE
>> >> - Full ibgp mesh
>> >> - Peering is to loopbacks
>> >> - OSPF as IGP
>> >> - Loopbacks in OSPF
>> >> - MPLS Enabled on Interfaces
>> >>
>> >>
>> >> OSPF cost between aR1 and aR2 is 1
>> >> OSPF cost between bR1 and bR2 is 1
>> >> OSPF cost between aR1 and bR1 is 250
>> >> OSPF cost betwen aR2 and bR2 is 500
>> >>
>> >> MTU 9216 between aR1 and aR2, aR1 and bR1, aR2 AND BR2
>> >> MTU 9182 between bR1 and bR2
>> >>
>> >>
>> >> IOS on aR1 and aR2 is 12.2.33.SRB2 - SUP720
>> >> IOS on bR1 and bR2 is 12.33.SRC - RSP720
>> >>
>> >>
>> >> i am stumped, any ideas would be helpful in trying to
>> understand why
>> >> the bgp session is going down due to expired hold time, when
>> all
>> >> links are up..
>> >>
>> >> thanks!
>> >>
>> >> ck
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >
>> >
>> > --
>> > ^christian$
>>
>> > _______________________________________________
>> > cisco-nsp mailing list cisco-nsp at puck.nether.net
>> > https://puck.nether.net/mailman/listinfo/cisco-nsp
>> > archive at http://puck.nether.net/pipermail/cisco-nsp/
>>
>>
>>
>>
>>
>> --
>> ^christian$
>>
>
>
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