Re: [Idr] draft-ietf-l2vpn-evpn

Satya Mohanty <smohanty@juniper.net> Fri, 15 March 2013 22:20 UTC

From: Satya Mohanty <smohanty@juniper.net>
To: "Ali Sajassi (sajassi)" <sajassi@cisco.com>, "idr@ietf.org" <idr@ietf.org>
Thread-Topic: draft-ietf-l2vpn-evpn
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Date: Fri, 15 Mar 2013 22:16:14 +0000
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Cc: "l2vpn@ietf.org" <l2vpn@ietf.org>, "Giles Heron (giheron)" <giheron@cisco.com>
Subject: Re: [Idr] draft-ietf-l2vpn-evpn
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Few comments,

1. Sec 8.3: Please consider putting in a line stating that the per ESI Route (type 4) carries a label with all 0s (like the Type 1 mandatory route) in the MP-Reach NLRI.

2. This is not explicitly sec 8 but I think there may be a discrepancy in the draft.  Page 27, top paragraph

   An PE may advertise the same single E-VPN label for all MAC addresses
   in a given EVI. This label assignment methodology is referred to as a
   per EVI label assignment. Alternatively, an PE may advertise a unique
   E-VPN label per <ESI, Ethernet Tag> combination. This label
   assignment methodology is referred to as a per <ESI, Ethernet Tag>
   label assignment. As a third option, an PE may advertise a unique E-
   VPN label per MAC address. All of these methodologies have their
   tradeoffs.

I see a problem with the third option (per-prefix allocation mode), related to aliasing in the Active/Active case.
In such a label allocation mode, what label will be associated with the per EVI AD route ?

Let's say PE1 and PE2 share the same ESI, PE1 and PE1 uses per prefix label  allocation mode, and PE2 uses either per EVI or per <ESI, Ethernet-tag> label allocation mode. As per the aliasing behavior, a mac route (say p1 with label l1) advertised from PE1, should be reachable from PE3 via PE2, irrespective of whether PE2 advertised p1 or not.  If PE2 did not advertise p1, but PE3 sends traffic to PE2, what label does PE3 slap on frames? As per the draft, it will slap the label what was received in the per EVI AD route. Moot question is what does it correspond to here ?

Should per-prefix label allocation be allowed? If it is, I think then the concept of aliasing will be lost, and all macs with the same EVI, ESI need to be advertised from each of the PEs configured to the same ES.

       PE1 -- --- --|
    /                       |_______
CE                         ________ RR-------PE3
   \                        |
      PE2 ---------|

Thanks,
--Satya

From: l2vpn-bounces@ietf.org [mailto:l2vpn-bounces@ietf.org] On Behalf Of Ali Sajassi (sajassi)
Sent: Tuesday, March 12, 2013 7:54 AM
To: idr@ietf.org
Cc: l2vpn@ietf.org; Giles Heron (giheron)
Subject: draft-ietf-l2vpn-evpn



In preparation for WG last call of this draft, our L2VPN chairs have asked us to solicit comments on the BGP section of this document (section 8).

http://www.ietf.org/id/draft-ietf-l2vpn-evpn-03.txt

Please kindly review this draft and post your comments by Friday March/29.

Thanks,
Ali

Re: [Idr] draft-ietf-l2vpn-evpn Susan Hares
[Idr] draft-ietf-l2vpn-evpn Ali Sajassi (sajassi)
Re: [Idr] draft-ietf-l2vpn-evpn Satya Mohanty
Re: [Idr] draft-ietf-l2vpn-evpn Jakob Heitz
Re: [Idr] draft-ietf-l2vpn-evpn Satya Mohanty