Hi Sasha,

What Luc mentioned below can work with any of the existing model supporting 
static PW because the pair of EVPN PEs terminating vES (with PW termination) 
act and look like a single logical PE to the CE. Therefore, the CE sees its PW 
being terminated by a single logical PE. EVPN provides the synch mechanism 
between the pair of PEs running vES. I agree with Luc that an example can be 
provided in the draft to describe how All-Active vES can be supported with PWs.

Cheers,
Ali

From: Alexander Vainshtein <alexander.vainsht...@ecitele.com>
Date: Tuesday, September 25, 2018 at 8:09 AM
To: "Luc Andre Burdet (lburdet)" <lbur...@cisco.com>
Cc: Michael Gorokhovsky <michael.gorokhov...@ecitele.com>, Alexander Ferdman 
<alexander.ferd...@ecitele.com>, Shell Nakash <shell.nak...@ecitele.com>, 
"bess@ietf.org" <bess@ietf.org>, 
"draft-sajassi-bess-evpn-virtual-eth-segment.auth...@ietf.org" 
<draft-sajassi-bess-evpn-virtual-eth-segment.auth...@ietf.org>, "p...@ietf.org" 
<p...@ietf.org>
Subject: RE: [bess] All-Active Multi-homing and Virtual Ethernet Segments: A 
Question
Resent-From: <alias-boun...@ietf.org>
Resent-To: Cisco Employee <saja...@cisco.com>, <pbris...@cisco.com>, 
<richard.sch...@verizon.com>, <jdr...@juniper.net>, 
<jorge.raba...@alcatel-lucent.com>
Resent-Date: Tuesday, September 25, 2018 at 8:09 AM

Luc,
Lots of thanks for a prompt and highly informative response.

I am adding the PALS WG to the CC list since, from my POV, your proposal goes 
beyond the PW network reference model as shown in Figure 2 of RFC 
3985<https://tools.ietf.org/html/rfc3985>.
While this model has been extended to cover multi-segment PWs (RFC 
6073<https://tools.ietf.org/html/rfc6073>), PW redundancy (RFC 
6718<https://tools.ietf.org/html/rfc6718>) and ICCP (RFC 
7275<https://tools.ietf.org/html/rfc7275>)  none of these extensions seem to be 
directly applicable to the proposed scheme.

My 2c,
Sasha

Office: +972-39266302
Cell:      +972-549266302
Email:   alexander.vainsht...@ecitele.com

From: Luc Andre Burdet (lburdet) [mailto:lbur...@cisco.com]
Sent: Tuesday, September 25, 2018 5:46 PM
To: Alexander Vainshtein <alexander.vainsht...@ecitele.com>; 
draft-sajassi-bess-evpn-virtual-eth-segment.auth...@ietf.org
Cc: Michael Gorokhovsky <michael.gorokhov...@ecitele.com>; Alexander Ferdman 
<alexander.ferd...@ecitele.com>; Shell Nakash <shell.nak...@ecitele.com>; 
bess@ietf.org
Subject: Re: [bess] All-Active Multi-homing and Virtual Ethernet Segments: A 
Question

Hi Sasha,

I agree the vES draft does not go in great detail about A/A PWs.

For A/A PWs terminating at peering PEs, the concept is similar to LAG, using 
static label at peering PEs:

  *   The CE sets up a single PW to remote endpoint to anycast IP1, Label1.
  *   PE1, PE2 set up a PW each to CE, using local static label Label1.
  *   PE1,PE2 adv IP1 as anycast IP towards CE-side
There will not be excessive MAC-moves since the CE sees only one pseudowire to 
a single remote—very similar to what is done for LAG on “real” links.

We can update the draft to be more descriptive—that draft needs a re-read 
anyways, the header on each page still reads “PBB-EVPN” ☺

HTH,
Luc André

[http://www.cisco.com/c/dam/m/en_us/signaturetool/images/banners/standard/09_standard_graphic.png]




Luc André Burdet
lbur...@cisco.com<mailto:lbur...@cisco.com>
Tel: +1 613 254 4814






Cisco Systems Canada Co. / Les Systemes Cisco Canada CIE
Cisco.com<http://www.cisco.com/web/CA/>







From: BESS <bess-boun...@ietf.org<mailto:bess-boun...@ietf.org>> on behalf of 
Alexander Vainshtein 
<alexander.vainsht...@ecitele.com<mailto:alexander.vainsht...@ecitele.com>>
Date: Tuesday, September 25, 2018 at 06:25
To: 
"draft-sajassi-bess-evpn-virtual-eth-segment.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-virtual-eth-segment.auth...@ietf.org>"
 
<draft-sajassi-bess-evpn-virtual-eth-segment.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-virtual-eth-segment.auth...@ietf.org>>
Cc: Michael Gorokhovsky 
<michael.gorokhov...@ecitele.com<mailto:michael.gorokhov...@ecitele.com>>, 
Alexander Ferdman 
<alexander.ferd...@ecitele.com<mailto:alexander.ferd...@ecitele.com>>, Shell 
Nakash <shell.nak...@ecitele.com<mailto:shell.nak...@ecitele.com>>, 
"bess@ietf.org<mailto:bess@ietf.org>" <bess@ietf.org<mailto:bess@ietf.org>>
Subject: [bess] All-Active Multi-homing and Virtual Ethernet Segments: A 
Question

Dear authors of the EVPN Virtual Ethernet 
Segment<https://tools.ietf.org/html/draft-sajassi-bess-evpn-virtual-eth-segment-03>
 draft,
My colleagues and I have a question pertaining to support of All-Active 
redundancy mode in EVPN that uses virtual Ethernet Segments.

Section 8.5 of RFC 7432<https://tools.ietf.org/html/rfc7432#section-8.5> says:

   If a bridged network is multihomed to more than one PE in an EVPN
   network via switches, then the support of All-Active redundancy mode
   requires the bridged network to be connected to two or more PEs using
   a LAG.

   If a bridged network does not connect to the PEs using a LAG, then
   only one of the links between the bridged network and the PEs must be
   the active link for a given <ES, VLAN> or <ES, VLAN bundle>.  In this
   case, the set of Ethernet A-D per ES routes advertised by each PE
   MUST have the "Single-Active" bit in the flags of the ESI Label
   extended community set to 1.

This restriction is easy to understand, since, with the All-Active multi-homing 
mode of an Ethernet Segment, a CE attached to such a segment potentially would 
receive traffic from all the PEs attached to this  segment. Since A CE that is 
part of a bridged network must learn MAC addresses of the received traffic, it 
would potentially experience continuous MAC Move events – with undesirable 
consequences.

The EVPN Virtual Ethernet Segment draft replaces Ethernet links (forming a 
“real” ES) with Ethernet PWs, and claims support of both Single-homed and 
multi-homed multi-homing modes. When I compare these claims with the quoted 
above statement from RFC 7432, I see two possibilities:

  *   Either a CE that is connected to an All-Active vES cannot be part of a 
bridged network (and thus would not do any MAC learning)
  *   Or  an extension of LAG that deals with Ethernet PWs instead of Ethernet 
links is required.

Could you please clarify which of these two options is correct?

Note: The draft includes Informative references to the two drafts that have 
been published as RFC 7432 and RFC 7623.

Regards,
Sasha

Office: +972-39266302
Cell:      +972-549266302
Email:   
alexander.vainsht...@ecitele.com<mailto:alexander.vainsht...@ecitele.com>


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