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
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