[j-nsp] graceful failover and software upgrades

[Pekka Savola]

Thanks for the procedures.  This is a nice start, because there isn't 
anything published on this.

A few comments inline..

On Fri, 18 Mar 2005, Jeff C. Strahl wrote:
> 1.   Enable Graceful restart to minimize/eliminate forwarding plane
> disruption .  You also need to enable graceful restart on peer nodes for it
> to buy you anything.

This brings up an interesting point which hasn't been clearly 
documented anywhere.

What's the relation of graceful restart support (at your neighbor 
nodes) and graceful switchover?

That is, if we have graceful switchover enabled, what happens if
  a) neighbor supports graceful restart
  b) neighbor does not support graceful restart

(And the currently the router is also configured to do graceful 
restart..)

My hunch is that the protocol sessions don't flap with a), and do flap 
with b). (The flap probably takes 2-10 seconds, the time it takes for 
the other RE to take control using the switchover..)

Anyone have concrete ideas about the relation of graceful restart and 
swichover ?

> 3. Manually switch (here is where graceful restart comes in) see the
> following

How long a break does this cause? Because the graceful switchover is 
not enabled, I think this will result in a break of 2-5 minutes -- 
correct ?

> 4. Upgrade primary RE by consoling in to it specifically
>
> 5. If step 3 worked well, switch mastership back to primary RE

I think you'll want to re-enable graceful switchover before doing 5, 
right?  Otherwise it'll result in another break.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings