That matches my view, Satoru. Still both edges require states hence the associated node has to have an interface to the control plane. But I agree that in total fewer states are required because egress does not need a host state for decap/re-write and removing the SRv6 header at egress is standard behavior.
marco -----Original Message----- From: Satoru Matsushima [mailto:satoru.matsush...@gmail.com] Sent: Mittwoch, 7. März 2018 12:23 To: Marco Liebsch Cc: dmm Subject: Re: [DMM] Fwd: I-D Action: draft-ietf-dmm-srv6-mobile-uplane-01.txt Marco, > 2018/03/07 18:41、Marco Liebsch <marco.lieb...@neclab.eu>のメール: > > Satoru, > > since I read this at different places, let me ask one clarifying question > about the stateless motivation: > > I see that for SRv6 you may not need a state at the egress (at least > not for traffic forwarding) but for Uplink/Downlink (UL/DL) you need a > state at both edges of the communication since the DL egress serves as uplink > ingress, correct? 2x unidirectional tunnels to form bidirectional paths require 4 states in total at both the ingress and egress. In SR case it requires just 2 states at the ingresses for both directions. Cheers, --satoru > > marco > > > -----Original Message----- > From: dmm [mailto:dmm-boun...@ietf.org] On Behalf Of Satoru Matsushima > Sent: Dienstag, 6. März 2018 17:23 > To: Tom Herbert > Cc: dmm > Subject: Re: [DMM] Fwd: I-D Action: > draft-ietf-dmm-srv6-mobile-uplane-01.txt > > Hello Tom, > >>> A Big progress is that the draft supports interworking with GTP over >>> IPv6 in addition to GTP over IPv4. >>> And we have made change SRv6 function to IPv6 encapsulation with SRH >>> instead of SRH insertion by default. >>> >> >> Hi Satoru, >> >> If there are no intermediate hops od SIDs being set when >> encapsulating would a SR header still be needed or could this just be >> simple IP in IP encpasulation? If is no SR header then it's possible >> that ILA might then be used to completely eliminate the encapsulation >> overhead. > > I think you’re right. You would find that case in the draft as ‘Traditional > Mode’ which is equivalent with traditional GTP-U case. You seem you say ILA > is also equivalent with that mode. In addition, this draft introduces > ‘Enhance Mode’ to cover more advanced cases. > > IMO SR is designed not to maintain path states except at an ingress node. So > the packet need to preserve original DA in the header that keep the egress > node in stateless. It would be great if ILA is designed in the similar > concept as well. > > If it’s not, it looks a kind of tradeoff, between reducing the overhead and > keeping the statelessness. It’s not apple-to-apple comparison. To decide to > choose which one need to be prioritized would depend on each deployment case > in operators IMO. > > Cheers, > --satoru > _______________________________________________ > dmm mailing list > dmm@ietf.org > https://www.ietf.org/mailman/listinfo/dmm _______________________________________________ dmm mailing list dmm@ietf.org https://www.ietf.org/mailman/listinfo/dmm
