Re: [RPRWG] CRC check in each node?
I think that one of the main reason for not discarding an errored packet in
the transit path is to be able to implement some sort of "far-end error
monitoring" (SONET/SDH concept). This way, we wouldn't have to specify
another protocol to implement such function.
jld.
Mike Takefman <tak@xxxxxxxxx>@majordomo.ieee.org on 06/25/2001 09:47:14 PM
Sent by: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
To: "ieee 802.17 list" <stds-802-17@xxxxxxxx>
cc:
Subject: Re: [RPRWG] CRC check in each node?
All,
An interesting point from 802.1D 1998 is the following.
"Note that the frame is completely received
before it is relayed as the Frame Check Sequence (FCS)
is to be calculated and the frame discarded if in
error."
It strikes me that if an 802.1D bridge must not relay a packet
with a bad FCS, there is nothing wrong with removing it in
the transit path of the 802.17 MAC (assuming that it can be
done). We are not changing the operation that will
occur, just making it happen sooner.
I did not see an example of guaranteeing deliverly of
a packet with "good" address and "bad" contents in current 802
networks. The FCS will alias bad address and bad contents and
since .1D specifies that packets with FCS errors will be removed
I do not understand how anything with an FCS error continues to
flow to an end station unless the LAN is a single segment.
I would appreciate a pointer to the relevant part of the standard
that describes how to do this type of operation across multiple
segments.
thanks,
mike