[j-nsp] Redundant RE setup useful?

[Darren O'Connor]

This was how I set up the last ISP network I worked on. All PE's had dual REs and P routers only had a single. The P's already have a back up in that there is another P router. Many customers only had a single link to a PE so the failure of an RE in that box would be catastrophic.

I must admit, I've only had to fail over to a backup RE twice in many years. 

Thanks
Darren
http://www.mellowd.co.uk/ccie



> Date: Mon, 23 Jun 2014 09:36:26 -0700
> From: tyler.christiansen at adap.tv
> To: scott at granados-llc.net
> CC: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] Redundant RE setup useful?
> 
> It also depends on your level of network resiliency.  If you have two
> separate devices where each device is fully capable of supporting all of
> the functionality alone, then dual REs don't make a lot of sense as you can
> just shut down one box.  We see this sort of thing when designing route
> reflectors or tiered reflectors.  Also in core topologies where you can
> lose one (or more) routers and still be able to handle all of your capacity
> without degradation.
> 
> For PE routers, though, dual RE can save your life.  And for P routers
> where you just don't have enough boxes (or circuits!) to pick up the slack
> if a few die.
> 
> Of course, if you can't design for failures centered around control plane
> failures in a single RE box, then you need dual RE...so it might be best to
> stick with dual RE to be safe anyway.
> 
> 
> On Mon, Jun 23, 2014 at 6:38 AM, Scott Granados <scott at granados-llc.net>
> wrote:
> 
> > I have seen one of the RE modules fail and the backup saved our bacon.
> >  There was a bad batch of SSD drive components that caused issues and the
> > card to crash.  I’ve also seen an upgrade fail and the disk not format
> > correctly rendering the card useless.  Again very remote possibility of
> > happening to you but possible.
> >
> > On Jun 23, 2014, at 4:07 AM, Joerg Staedele <js at tnib.de> wrote:
> >
> > > Hi there,
> > >
> > > i am asking myself if it really makes sense to have a redundant RE setup
> > in M and MX-series. Maybe some of you could tell me if they had a scenario
> > where it really helped to prevent an outage.
> > >
> > > I am not talking about ISSU/NSSU feature where it is needed.
> > >
> > > We didn't have a failed RE since years so for now all our redundant
> > setups seem not make any sense at all.
> > >
> > > What are your experiences?
> > >
> > > Regards,
> > > Joerg
> > >
> > >
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> 
> 
> -- 
> *Tyler Christiansen | Technical Operations*
> tyler <http://adap.tv/>@adap.tv <http://adap.tv/> | www.adap.tv
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