[rbak-nsp] Subcriber route and metric

[Raphael Mazelier]

Le 18/01/2013 13:05, Blake Willis a écrit :
>
> Bonjour Raphael,
>
Salut Blake, (le monde est petit, passe le bonjour à Sam)
> Welcome to the joys of Redback subscriber routing... I'm not sure what 
> SEOS version you're running or whether their architecture has changed 
> in recent releases, but in the 6.1 trains I'm most familiar with, 
> subscriber routes have the particularity of not being able to 
> load-balance or handle redundancy properly. The behavior is as you 
> describe.  When trying to load-balance across multiple subscriber 
> routes with the same metric, the box will even go so far as to install 
> all three next-hops in the FIB and blackhole traffic to all but the 
> most recent connection.  I observed the same behavior running RIP with 
> the CPE learning three identical routes, but I believe this may have 
> been fixed in recent releases.
>
I'm running 6.1 version also, so I'm exactly in the same situation.
I don't know if it have been fixed, but a firmware upgrade is just 
unthinkable (old hardware, old and exotic configuration).

> We have used a couple of workarounds, none of which are particularly 
> nice but they do get the job done:
>
>  - cut your "primary" /24 route into two /25s so that the shortest 
> prefixes will be preferred and you don't have the same set of routes 
> pointing at each subscriber (increases framed-route count by 50% 
> though)-:
>
Aha love this one, but I'm not sure it was a good idea for mass deployment ?

>  - create "primary" and "backup" contexts, and make sure that two 
> logins from the same site never show up in the same context.
>
Yep I already think of this possibility, running some igp between 
context to correctly reroute the traffic. It complex the configuration 
and design but It seem more elegant on the paper.

> As a side note, you'll also find that the framed-routes are really 
> bound to the subscriber circuit & not the IP next-hop in the 
> framed-route.  You can put just about anything as a next-hop in radius 
> and the traffic will still go down the subscriber circuit.
>
Ok. I've read something about that, but I'm wasn't sure I understood 
correctly. Now I am.

> Hope that helps.
>
Sure. You confirm I'm not missed something, and now I can think at the 
better solution for my need.
For now manually configured static route with dvsr is ok, but for mass 
provisionning is not an option.

> Best regards,
More general subject, what is your advice about a SE400 lns replacment 
?  Cisco ASR ? or ?


Regards;

-- 
Raphael Mazelier

.