[bess] Last call comment to draft-ietf-bess-evpn-inter-subnet-forwarding-05

Linda Dunbar <linda.dunbar@huawei.com> Thu, 04 October 2018 16:30 UTC

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From: Linda Dunbar <linda.dunbar@huawei.com>
To: "bess@ietf.org" <bess@ietf.org>, "ietf@ietf.org" <ietf@ietf.org>
Thread-Topic: Last call comment to draft-ietf-bess-evpn-inter-subnet-forwarding-05
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Date: Thu, 4 Oct 2018 16:30:37 +0000
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Subject: [bess] Last call comment to draft-ietf-bess-evpn-inter-subnet-forwarding-05
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Ali, et al:

Sorry for the late comments. I remember reviewing/contributing to this draft many years ago. Happy to see it is finally moving to IESG Last Call.

The draft describes the mechanism to allow TSs belonging to different subnets attached to same PE to be communicated by the PE (instead hair pinned to the L3GW). Very good optimization.

However, not every PE has the needed policies for any two subnet communication (that is why the traffic was to be sent to L3GW). Therefore, the draft needs a section to describe how the PEs determine if it has the needed policies for specific inter subnets communication.
In addition, when subnets are scatted among many different PEs, it requires the L3GW to maintain all the mappings. In Data center when there are many VMs or Containers, the number of mappings for L3GW to maintain is huge (it practically becomes host routing for tens of thousands of VMs or Containers). It doesn't scale well. Therefore, the mechanism should allow some PEs to maintain some of the mappings, i.e. becoming a designated L3GW for some subnets.

If you are willing to accept this comment, I can provide the text on "Inter-subnet communication Policy on PE".

Thank you.

Linda Dunbar