[j-nsp] Optimizing the FIB on MX

[Vincent Bernat]

 ❦ 18 février 2016 10:50 GMT, Adam Vitkovsky <Adam.Vitkovsky at gamma.co.uk> :

>> You are right. I didn't understand your answer the first time as I thought that
>> PIC was for "programmable integrated circuit", so I thought this was a plan
>> for Juniper to fix the problem with some dedicated piece of hardware.

> Sorry about that, I'll try to be more explicit in my future posts.
>
> The setup is really easy
[...]

Oh, many thanks for the detailed setup! I'll need some time to update to
15.1 and I'll get back to you with the results once this is done.

> 5)always prefer eBGP over iBGP*
> set policy-options policy-statement FROM_TRANSIT term INGRESS_POLICY_A then preference 169 <<or whatever works for you
>
> -by default,
> If the MX140-A from our previous example loses its Transit link it will (via BGP-PIC) immediately reroute traffic to MX140-B
> However by default MX140-B has a best path via MX140-A -so until it
> receives withdrawn from MX140-A it'll loop traffic back to MX140-A.
> That's why you want MX140-B to prefer it's local exit.
>
> *not sure what was Juniper and ALU thinking when they came up with the
> same protocol preference for eBGP and iBGP routes, there's a ton of
> reasons why you always want to prefer closest AS-EXIT.

Unfortunately, I don't have the same upstream on both MX and for some
routes, one of them may have a better route than the other. The two MX
are advertising just a default, so they can attract traffic that would
be better routed by their neighbor. I'll try to think a bit about what's
more important.
-- 
Make sure your code "does nothing" gracefully.
            - The Elements of Programming Style (Kernighan & Plauger)