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BGP UPDATE-v2

BGP UPDATE-v2. Gargi Nalawade Himanshu Shah. Problem description . Current UPDATE message was intended to carry IPv4 NLRIs Non-IPv4 NLRIs as well as NEXTHOP are carried in MP_REACH and MP_UNREACH attributes. MP_REACH / MP_UNREACH are attributes, but carry NLRIs.

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BGP UPDATE-v2

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  1. BGP UPDATE-v2 Gargi Nalawade Himanshu Shah

  2. Problem description • Current UPDATE message was intended to carry IPv4 NLRIs • Non-IPv4 NLRIs as well as NEXTHOP are carried in MP_REACH and MP_UNREACH attributes. • MP_REACH / MP_UNREACH are attributes, but carry NLRIs. • In case of attribute length errors, there is no way to figure out which AFI/SAFI the update belongs to. • Not good for AFI/SAFI separation, since AFI/SAFI is not known in case of attribute length errors

  3. BGP Update – Encodings Current UPDATE Suggested UPDATE

  4. BGP Update – v2 Encoding +------------------------------------------------------------------------+ | AFI (2 octets) | +------------------------------------------------------------------------+ | SAFI (1 octets) | +------------------------------------------------------------------------+ | Reserved (2 octets) | +------------------------------------------------------------------------+ | Withdrawn Routes Length (2 octets) | +------------------------------------------------------------------------+ | Withdrawn Routes (variable) | +------------------------------------------------------------------------+ | Total Path Attribute Length (2 octets) | +------------------------------------------------------------------------+ | Path Attributes (variable) | +------------------------------------------------------------------------+ | Network Layer Reachability Information (variable) | +------------------------------------------------------------------------+

  5. BGP Update – v2 – Spec changes • New message type. • New capability to support UPDATE-v2 message. • MP_REACH and MP_UNREACH attributes are obsoleted in the new UPDATE-v2 message. • NEXTHOP attribute will have the encoding as defined in "BGP NEXTHOP-v2“ draft (draft-lefaucheur-bgp-mp-nexthop-01.txt). • If peer supports UPDATE-v2, then it shouldn’t accept current UPDATE message (current UPDATE message).

  6. BGP UPDATE-v2 • All attributes other than NEXTHOP remains same. • Doesn’t have ability to carry more than one AFI/SAFI in an update message, but who does that anyway? • Can achieve Address-family separation since AFI/SAFI is the first tuple in the UPDATE message.

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