[rbridge] Trivial question about FCS in Figure 3 of current protocol draft

[Eastlake III Donald-LDE008]

See Section 4.1.4.

The FCS is commonly something that's buried in the port hardware and
gets generated at the time of or just before frame transmission and
checked at the time of or just after receipt and sometimes doesn't exist
in the interior of a bridge/Rbridge.

Since Figures 3 and 7 say they are a frame as it appears on the wire,
which is what IETF protocol descriptions are normally interested in, one
and only one FCS should be shown.

Donald

-----Original Message-----
From: rbridge-bounces at postel.org [mailto:rbridge-bounces at postel.org] On
Behalf Of Radia Perlman
Sent: Sunday, October 21, 2007 12:39 AM
To: Developing a hybrid router/bridge.
Subject: [rbridge] Trivial question about FCS in Figure 3 of
currentprotocol draft

Figure 3 (bottom of page 9) has "Ethernet FCS". Since there are two 
Ethernet headers
(inner and outer), wouldn't there be two Ethernet FCS's? Should the 
diagram simply
omit "Ethernet FCS" or put it twice? Or is it correct somehow and I'm 
not looking at it right,
or do we actually intend to omit the inner Ethernet frame's FCS?

Thanks,

Radia
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