RE: [RPRWG] RPR: packet sequencing between multicast andunicast
What about unknown flooding vs. unicast ?
You need to deal with the same complexity anyway if you
are serious about ordering issue, unless you don't support
802.1D transparent bridging of RPR.
William Dai
-----Original Message-----
From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
[mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx]On Behalf Of Heng Liao
Sent: Wednesday, June 20, 2001 11:30 AM
To: 'stds-802-17@xxxxxxxx'
Subject: [RPRWG] RPR: packet sequencing between multicast and unicast
Hi all,
Ethernet multicast: according to 802.1D, packet ordering is based on the
3-tuple <source MAC address, destination MAC address, priority>. All
packets received by a bridge that can be identified by a given tuple must
not be misordered by the bridge when the packet is retransmitted. There is
no particular distinction between multicast destination addresses and
unicast destination addresses. Thus it is permissible to arbitrarily reorder
multicasts with respect to unicasts from the same source, subject of course
to the usual limitations of protocol timers.
For RPR, it would be nice to allow arbitrarily reorder multicasts with
respect to unicast in a similar way. This can significantly reduce the
implementation cost of multicast. Basically, it relaxes the requirement of
instantaneous packet replication (multicast packet needs to be put into
receive queue and transit queue at the same time). This may be easy to do in
some implementations, it may also be very hard to do in others.
- Heng Liao
PMC-Sierra, Inc.