Subject: [bess] Comments on draft-ietf-bess-mvpn-expl-track-03

From: Xiejingrong <[email-masked]>
Date: Thu, 21 Dec 2017 09:22:56 +0000

I have a comment on draft-ietf-bess-mvpn-expl-track-03.

The chap 5.3 of this document said:

Furthermore, if the PTA specifies "no tunnel info", the LIR and LIR-pF
flags in the PTA MUST be passed along unchanged.

   This will ensure that an egress ABR/ASBR only sends a Leaf A-D route
   in response to a "match for tracking" if it is on the path to an
   egress PE for the flow(s) identified in the corresponding S-PMSI A-D
   route.

The issue is as follow:
In a [IngressPE--EgressABR--EgressPE] topology, IngressPE send a Wildcard S-PMSI(*,*) route with PTA(flag<LIR+LIR-pF>), whose NLRI is donated as  SPMSI(type<0/1/2>RD,*,*,IngressPE). This SPMSI route will be relayed by EgressABR to EgressPE with PTA flag untouched. Then EgressPE will generate ONE LeafAD route with NLRI(type<0/1/2>RD,*,*,IngressPE,EgressPE) and RT<EgressABR> and N(N>=0) LeafAD routes with NLRI(type<16/17/18>RD,S,G,IngressPE,EgressPE) and RT<EgressABR>. All according to chap 5.2 of this document.

Then according to chap 5.3  of this document:
IngressABR will only send a Leaf A-D route, It should be the ONE of LeafAD(type<0/1/2RD,*,*,IngressPE,EgressABR) with RT<IngressABR>.
Then how should IngressABR deal with the the N(N>=0) LeafAD routes with NLRI(type<16/17/18>RD,S,G,IngressPE,EgressPE) and RT<EgressABR> ?
It is not clarified in RFC7524 either. See chap 7.1 of RFC7524, which only clarify LeafAD route with type<0/1/2>RD.
Should such LeafAD route with type<16/17/18>RD be accepted and installed by EgressABR, and then 'relay' back to IngressPE, and thus enable IngressPE explicit tracking inside the ingress "segmentation domain" ?

Thanks.

XieJingrong