RE: [RPRWG] CRC check in each node?
I absolutely agree. If at all possible we should not regenerate the user's
data packet CRC (assuming the MAC encapsulates Ethernet frames) unless
necessary. If the packet is sitting in non-parity or ECC memory awaiting
transmission and the CRC is regenerated at each node there is a lot of
opportunity for undetected (or late, i.e. the entire FTP file transfer has
to be completed) error.
It would be optimal for any encapsulation or header that .17 puts on a
packet to not effect the user CRC.
Ray Zeisz
LVL7 Systems
http://www.LVL7.com
(919) 865-2735
-----Original Message-----
From: Denton Gentry [mailto:denny@xxxxxxxxxxxxxxxxxx]
Sent: Thursday, June 21, 2001 10:57 PM
To: stds-802-17@xxxxxxxx
Subject: Re: [RPRWG] CRC check in each node?
I'd prefer the TTL not be included in the same CRC used over the
user data. If a packet traverses N nodes on the ring, there would
be N places where failing hardware could result in undetected data
corruption of the user's data.
If the CRC is left intact all the way across the ring, there are only
two places where the packet could be corrupted undetected (the source
and the destination).
As for whether to strip bad packets at each node: never optimize
for errors. I don't think increased efficiency in handling bad
packets is worth added complexity in the MAC.