[j-nsp] next-hop self and RR

[chip]

With other platforms next-hop-self is applied as a bgp attribute in
the configuration of the process.  When that's done, they usually
follow the RFC faithfully in that regard.  However upon applying
outbound policy the next-hop attribute is allowed to be modified.  To
me, modification of the next-hop attribute that can only be modified
with outbound policies is what Junos is allowing you to do here and
that matches up with the way other platforms are enabling this
ability.

--chip



On Thu, Nov 8, 2012 at 10:45 AM, Mihai Gabriel <mihaigabriel at gmail.com> wrote:
> Hello,
>
>  Is Juniper's implementation of next-hop self on a RR a violation of
> RFC1966?
>
> " In some implementations, modification of the BGP path attribute,
>    NEXT_HOP is possible. For example, there could be a need for a RR to
>    modify NEXT_HOP for EBGP learned routes sent to its internal peers.
>    However, it must not be possible for an RR to set on reflected IBGP
>    routes as this breaks the basic principle of Route Reflection and
>    will result in potential black holeing of traffic."
>
> Testing this feature in a topology with 3 routers, r1 (client) - r3 (rr) -
> r2 (client) , a route originated from r1 and advertised to r2 via  it's RR
> will have a next-hop of RR when an export policy is applied to r2:
>
> mihai at mx5t# run show route receive-protocol bgp 10.0.6.1 logical-system r3
> 192.168.10.0
>
> inet.0: 32 destinations, 33 routes (32 active, 0 holddown, 0 hidden)
>   Prefix  Nexthop       MED     Lclpref    AS path
> * 192.168.10.0/24         10.0.6.1                     100        I
>
> mihai at mx5t# show protocols bgp group 65000 neighbor 10.0.6.2
> export nh-self;
>
> show policy-options policy-statement nh-self
> from {
>     protocol bgp;
>     neighbor 10.0.6.1;
> }
> then {
>     next-hop self;
> }
>
> mihai at mx5t# run show route advertising-protocol bgp 10.0.6.2 logical-system
> r3 match-prefix 192.168.10.0
>
> inet.0: 32 destinations, 33 routes (32 active, 0 holddown, 0 hidden)
>   Prefix  Nexthop       MED     Lclpref    AS path
> * 192.168.10.0/24         Self                         100        I
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-- 
Just my $.02, your mileage may vary,  batteries not included, etc....