[c-nsp] BGP Hold Time Expired, but why?
Christian Koch
christian at broknrobot.com
Tue Jul 22 07:54:13 EDT 2008
they are all 7609-S
On Tue, Jul 22, 2008 at 5:25 AM, Ozgur Guler <gulerozgur at yahoo.co.uk> wrote:
> Is this a GSR?
>
>
>
> --- On *Tue, 22/7/08, Christian Koch <christian at broknrobot.com>* wrote:
>
> From: Christian Koch <christian at broknrobot.com>
> Subject: Re: [c-nsp] BGP Hold Time Expired, but why?
> To: "Oliver Boehmer (oboehmer)" <oboehmer at cisco.com>
> Cc: "cisco-nsp" <cisco-nsp at puck.nether.net>
> Date: Tuesday, 22 July, 2008, 1:58 AM
>
>
> 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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>
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