[j-nsp] JunOS interop problems with RFC5549

[Brian Rak]

On 2/19/2019 4:08 PM, Bjørn Mork wrote:
> Brian Rak <brak at gameservers.com> writes:
>
>> They both negotiate the Extended next hop capability, and JunOS
>> accepts the routes just fine if I make Cumulus only send 16 byte
>> nexthops (still IPv6, just not containing a link-local address)
> Ah, right.  And the RFC2545 requirements are also fulfilled?:
>
>     The link-local address shall be included in the Next Hop field if and
>     only if the BGP speaker shares a common subnet with the entity
>     identified by the global IPv6 address carried in the Network Address
>     of Next Hop field and the peer the route is being advertised to.
>
>     In all other cases a BGP speaker shall advertise to its peer in the
>     Network Address field only the global IPv6 address of the next hop
>     (the value of the Length of Network Address of Next Hop field shall
>     be set to 16).
>
>
>
> Bjørn
In this case, they're peering over an IPv6 link-local address. The next 
hop field contains the link local address repeated twice.  The RFC is 
not particularly clear on what to do if there's no global address available.