IPv6 routing protocols

Iljitsch van Beijnum iljitsch at muada.com
Fri Jun 10 05:37:34 CDT 2011


On 10 jun 2011, at 12:27, Iljitsch van Beijnum wrote:

> RFC 4760:

>   An UPDATE message that carries the MP_REACH_NLRI MUST also carry the
>   ORIGIN and the AS_PATH attributes (both in EBGP and in IBGP
>   exchanges).  Moreover, in IBGP exchanges such a message MUST also
>   carry the LOCAL_PREF attribute.

Sorry, this is stupid. I should have read beyond "LOCAL".

So it depends a little, but I still don't see any implementation leeway in RFC 2545:

3. Constructing the Next Hop field

   A BGP speaker shall advertise to its peer in the Network Address of
   Next Hop field the global IPv6 address of the next hop, potentially
   followed by the link-local IPv6 address of the next hop.

   The value of the Length of Next Hop Network Address field on a
   MP_REACH_NLRI attribute shall be set to 16, when only a global
   address is present, or 32 if a link-local address is also included in
   the Next Hop field.

   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).



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