[j-nsp] MX960 Redundant RE problem

[Stefan Fouant]

Morgan,

You are correct if you are running GRES only, however if you enable NSR basically the Backup RE also actively runs rpd and maintains state adjacencies, etc, so in the event of a Primary RE failure you will not need to reestablish  adjacencies, etc.

The cool thing is the Backup RE is actually listening to all the control plane messages coming on fxp1 destined for the Master RE and formulating it's own decisions, running its own Dijkstra, BGP Path Selection, etc. This is a preferred approach as opposed to simply mirroring routing state from the Primary to the Backup is because it eliminates fate sharing where there may be a bug on the Primary RE, we don't want to create a carbon copy of that on the Backup.

Stefan Fouant
JNCIE-SEC, JNCIE-SP, JNCIE-ER, JNCI
Technical Trainer, Juniper Networks

Follow us on Twitter @JuniperEducate

Sent from my iPad

On Feb 15, 2012, at 2:56 AM, Morgan McLean <wrx230 at gmail.com> wrote:

> Correct me if I'm wrong, but backup routing engines never have adjacencies
> or peering relationships etc because they are not active, correct? When
> they become master they have to reestablish those sessions. Thats how it
> seems to be for our SRX routing engines, at least, but routes are shared
> between the two so that during the time it takes for those things to
> reestablish, the routes are still moving traffic.
> 
> I might be wrong, but that was my impression.
> 
> Morgan
> 
> 2012/2/14 Mohammad <masalbad at gmail.com>
> 
>> Hi everyone
>> 
>> 
>> 
>> We have an MX960 with two routing engines, Re0: Backup, Re1: Master
>> 
>> When we try to switchover to the backup RE we see the following message:
>> 
>> XXX# run request chassis routing-engine master switch
>> 
>> error: Standby Routing Engine is not ready for graceful switchover
>> (replication_err soft_mask_err)
>> 
>> Toggle mastership between routing engines ? [yes,no] (no)
>> 
>> Noting that we used to switchover between the two Res a day a before with
>> no
>> issues!!!!
>> 
>> 
>> 
>> Also, when we login to the re0 (backup) and check the isis, rsvp, etc… we
>> see the following:
>> 
>> XXX> request routing-engine login other-routing-engine
>> 
>> €
>> 
>> --- JUNOS 10.2R3.10 built 2010-10-16 19:24:06 UTC
>> 
>> {backup}
>> 
>> XXX> show isis adjacency
>> 
>> 
>> 
>> {backup}
>> 
>> XXX> show rsvp session
>> 
>> Ingress RSVP: 0 sessions
>> 
>> Total 0 displayed, Up 0, Down 0
>> 
>> 
>> 
>> Egress RSVP: 0 sessions
>> 
>> Total 0 displayed, Up 0, Down 0
>> 
>> 
>> 
>> Transit RSVP: 0 sessions
>> 
>> Total 0 displayed, Up 0, Down 0
>> 
>> 
>> 
>> {backup}
>> 
>> XXX>
>> 
>> While we can see the bgp routes and L3VPN routes,,,!!!!
>> 
>> We have tried to replace the backup with another one, but with the same
>> results
>> 
>> Any ideas, this issue is really confusing us, and it is a very critical
>> router in our network.
>> 
>> 
>> 
>> Thank you in advance
>> 
>> Mohammad Salbad
>> 
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