Subject: Re: Highly Available OSPF Router.

From: [email-masked]
Date: Mon, 16 Feb 2004 01:34:32 -0600

Swami/Sean,

Your questions about why/where do we need this..

One example would be on a multiblade system where one blade (the
central processor) is running OSPF and distributing the routes to 
all other blades (the forwarding units). The forwarding units just 
forward the traffic using the forwarding table received from the 
central processor. Let say this central processor has a backup (
otherwise the whole system will be down when the central processor
dies). Now when the active central processor dies, the standby
central processor takes over. As the standby central processor does
not have any dynamic OSPF state, the adjacencies are re-formed. 
While OSPF is converging, the forwarding blades are not able to
forward the traffic.

If we wanted to make the standby central processor "hot standby", we
need to synchronize the OSPF state between the active and the standby
so that the standby can takeover immediately without breaking the
adjacencies.

Does it make any sense ??

Regards
Mukesh

> -----Original Message-----
> From: Mailing List [mailto:[email-masked]]On Behalf Of ext
> Ramalingam, Swaminathan (Swaminathan)
> Sent: Sunday, February 15, 2004 11:24 PM
> To: [email-masked]
> Subject: Re: Highly Available OSPF Router.
> 
> 
> Mukesh,
> Do u mean multi-level hierarchy in OSPF?. Present two-level 
> hierarchy in
> OSPF is too good enough to achieve scalability in any big 
> network. Do you
> really see any necessity for this?. If so, could you explain 
> where it can be
> useful?.
> 
> Swami
> 
> >-----Original Message-----
> >From: [email-masked] [mailto:[email-masked]]
> >Sent: Monday, February 16, 2004 12:33 PM
> >To: [email-masked]
> >Subject: Highly Available OSPF Router.
> >
> >
> >Has anyone implemented an OSPF HA where two or more OSPF routers
> >appear as one OSPF router to the OSPF neighbors. One of the routers
> >(the Master) talks to the external world (OSPF neighbors) and the
> >others (the Backups) keep all the dynamic OSPF state (neighbors,
> >database etc) in sync with the Master. When the Master dies, one of
> >the backup router takes over immediately without the neighbors
> >realizing any change in the network ?
> >
> >If anyone has implemented any such thing, I would like to hear about
> >how they do it. I would also like to know if the WG would be 
> interested
> >in standardizing such a mechanism ? At least I think that it will be
> >a useful thing !!
> >
> >Regards
> >Mukesh
> >
>

---

From: Manav Bhatia <[email-masked]>
Date: Mon, 16 Feb 2004 14:00:38 +0530

Mukesh,

Here you're talking about the internals of a protocol implementation (in
your specific case OSPF), that will definitely vary from vendor to vendor
and from implementation to implementation. Besides, such extensions
(hopefully) should not affect the implementation's/protocol's external
behavior (which is what really requires specification), because if it does,
it is a bug!

Manav

----- Original Message -----
From: <[email-masked]>
To: <[email-masked]>
Sent: Monday, February 16, 2004 1:04 PM
Subject: Re: Highly Available OSPF Router.

Swami/Sean,

Regards
Mukesh