[rbridge] Hop Count processing
Dinesh G Dutt
ddutt at cisco.com
Fri May 8 15:30:06 PDT 2009
I'd like to modify the hop count processing in section 3.6 (of draft 12)
slightly. The advantages of this alignment are:
- Make it possible to implement something like L2 traceroute
- Align it with what is done in other protocols such as IP and MPLS
for development and operational simplicity.
- Not forward a frame that will be dropped by the next hop.
The existing text at the beginning of 3.6 is:
The Hop Count field is a 6-bit unsigned integer. Each RBridge that is
about to forward a TRILL data or ESADI frame MUST check this field
and discard the frame if this field is zero. If this field is greater
than or equal to 1, it MUST be decremented in the forwarded frame.
The suggested replacement is:
The Hop Count field is a 6-bit unsigned integer. It is decremented by 1
by each Rbridge that forwards a TRILL encapsulated frame. The frame is
dropped if either the Hop Count in the received frame is 0 or the Hop
Count is decremented to 0.
We make our world significant by the courage of our questions and by
the depth of our answers. - Carl Sagan
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