Subject: [OSPF] draft-ietf-l3vpn-ospfv3-pece-05 - ext. community

From: Peter Psenak <[email-masked]>
Date: Wed, 31 Mar 2010 11:07:22 +0200

Bringing this up to the WG list to get the feedback. The discussion is 
about the usage of the BGP extended communities as defined for OSPFv2 
versus the definition of the new one in the context of the OSPFv3 PE-CE.

- draft-ietf-l3vpn-ospfv3-pece-05 defines a new OSPFv3 Route Extended 
Communities Attribute, which carries the exact same information as the 
original OSPF ext. communities defined in RFC4577.

- given that most vendors that will implement 
draft-ietf-l3vpn-ospfv3-pece-05 have already implemented RFC4577, 
reusing the communities defined there would make sense.

- from the operational perspective people are familiar with the original 
OSPF communities from the VPNv4 deployments, so they would appreciate 
the familiarity with those.

- in the last WG meeting an argument has been used that the route-types 
encoding in 4.4 of draft-ietf-l3vpn-ospfv3-pece-05 does not match the 
one defined for OSPFv2 in 4.2.6. of RFC4577. The Route Type filed in 
OSPF Route Type Extended Communities Attribute as defined in RFC4577 has 
enough space to use the encoding as defined in 
draft-ietf-l3vpn-ospfv3-pece-05 and there would be no collision. An 
alternative is to use the route-types as defined for OSPFv2 
(intra/inter/external/nssa) that match OSPFv3 route-types anyway - there 
is no need to carry the LSA type in this context.

- draft-ietf-l3vpn-ospfv3-pece-05 uses the IPv6 Address Specific BGP 
Extended Community Attribute (RFC5701) that was defined specifically to 
carry the IPv6 address. Not sure if it's usage as a placeholder for 
opaque data was the intention of RFC570 as such.

- other protocols are reusing the originally defined communities in IPv6 
VPN context.

thanks,
Peter