RE: [RPRWG] questions on RPR alternatives
Ravi,
- Some anwers to 802.1w vs RPR can be found in
http://www.ieee802.org/rprsg/public/presentations/nov2000/802.3_letter.pdf
- I believe 802.1w can provide comparable protection speed with
small number of nodes and ring sizes. However, it is based on STP
(Spanning Tree Protocol) and as a result, loses a ring span in the
ring topology. Such a loss of ring span also prevents shortest path
frame delivery over the ring.
- As for the advantages over other higher layer technologies, I would
pick RPR's dynamic bandwidth sharing capability (given comparable
protection speed).
Regards,
BJ
-----Original Message-----
From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
[mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx]On Behalf Of
ravi.chandran@xxxxxxxxxxx
Sent: Monday, June 04, 2001 5:28 PM
To: stds-802-17@xxxxxxxx
Subject: [RPRWG] questions on RPR alternatives
Hi
I'm new to RPR, and I'm trying to understand its applications and
compare it to other alternatives. I hope someone can help me with the
following questions:
- What is the difference between 802.1w (when used on a ring) and
802.17 in terms of the functionality provided? At a high level, they
both appear to support similar capabilties (at least in terms of
protection, which appears to be the most important feature), so I'm
trying to see whether I'm missing something here. (I understand that
802.17 is defining a L2 protocol while 802.1w is a higher layer
protocol.)
- What are the advantages of 802.17 over 802.1w as far as supporting
dual counter-rotating ring topologies are concerned?
- From a cost point of view, would 802.1w have a cost advantage since
Ethernet MAC/PHYs are readily available on the market and have high
volumes? (I am aware of only one RPR-type MAC chip on the market from
Conexant that supports Cisco's SRP.)
- From a TTM point of view, 802.1w is probably nearer to completion as
a standard since it is already on its 10th draft. Would 802.1w be a
competitive alternative to 802.17?
- I guess a more general question to ask is: can the
features/advantages that are targeted by 802.17 MAC be achieved just as
well (in terms of both performance and cost) by using other
standardized higher layer approaches. (For instance, another higher
layer approach that comes to mind is the use of MPLS-TE to perhaps set
up a primary LSP and a backup LSP on different rings, between each pair
of nodes, where the rings are running Ethernet.)
Thank you.
Ravi
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Ravi Chandran
Data Access & Transport Group
Tellabs Operations, Inc. phone : (219) 258-6410
3740 Edison Lakes Parkway fax : (219) 258-6446
Mishawaka, IN 46545 ravi.chandran@xxxxxxxxxxx
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