[j-nsp] improving global unicast convergence (with or without BGP-PIC)

[Alexander Arseniev]

Hi there,

The benefit is that value of INH mapped to a 100,000s of prefixes can be 
quickly rewritten into another value - for a different INH pointing to 
another iBGP peer.

Without INH, the forwarding NH value of EACH and EVERY prefix is 
rewritten individually and for longer period of time.

Your example of "correctly programmed INH" with LFA show 2 preprogrammed 
forwarding NHs which is orthogonal to the original topic of this discussion.

INH could be preprogrammed with one or multiple forwarding NHs, and to 
achieve "multiple forwarding NHs" preprogramming, one uses ECMP, (r)LFA, 
RSVP FRR, etc.

HTH

Thx

Alex


On 19/04/2017 12:51, adamv0025 at netconsultings.com wrote:
>> Of Alexander Arseniev
>> Sent: Wednesday, April 19, 2017 11:51 AM
>> - then 203.0.113.0 will appear as "indirect" and You can have the usual
> INH
>> benefits. Example from my lab:
>>
>> show krt indirect-next-hop | find "203.0.113."
>>
>> Indirect Nexthop:
>> Index: 1048592 Protocol next-hop address: 203.0.113.0
>>     RIB Table: inet.0
>>     Policy Version: 1                     References: 1
>>     Locks: 3                              0x9e54f70
>>     Flags: 0x2
>>     INH Session ID: 0x185
>>     INH Version ID: 0
>>     Ref RIB Table: unknown
>>           Next hop: #0 0.0.0.0.0.0 via ae4.100
>>           Session Id: 0x182
>>         IGP FRR Interesting proto count : 1
>>         Chain IGP FRR Node Num          : 1
>>            IGP Resolver node(hex)       : 0xb892f54
>>            IGP Route handle(hex)        : 0x9dc8e14      IGP rt_entry
>> protocol        : Static
>>            IGP Actual Route handle(hex) : 0x0            IGP Actual
>> rt_entry protocol : Any
>>
>> Disclaimer - I haven't tested the actual convergence with this setup.
>>
> But what good is an indirect next-hop if it's pointing to just a single
> forwarding next-hop??
>
> Example of correctly programed backup NHs for a BGP route:
> ...
> #Multipath Preference: 255
> Next hop: ELNH Address 0x585e1440 weight 0x1, selected  <<<eBGP primary path
> Next hop: ELNH Address 0x370c8698 weight 0x4000               <<< PIC backup
> via iBGP
>    Indirect next hop: 9550000 1048589 INH Session ID: 0x605
>       Next hop: 10.0.20.1 via ae1.0 weight 0x1 <<< IGP primary path
>       Next hop: 10.0.10.1 via ae0.0 weight 0xf000 <<< LFA backup path
>
> -I doubt you can get this with a static default route
>
> For the above you need to allow for multiple NHs to be programed into FIB
> using:
> set policy-options policy-statement ECMP then load-balance per-packet
> set routing-options forwarding-table export ECMP
>
> adam
>
> netconsultings.com
> ::carrier-class solutions for the telecommunications industry::
>