[rbridge] Default Link Costs in base protocol -13
Dinesh G Dutt
ddutt at cisco.com
Thu Jul 30 08:22:29 PDT 2009
Radia Perlman wrote:
> No objection, though perhaps if there are only a few (say less than 10)
> different link speeds in common use,
> it might be useful to enumerate the default costs for each of those values.
Doesn't IS-IS specify something like this already ? If it didn't, I'd
probably stay with the formula used by IEEE in computing the link cost
in spanning tree protocol unless there is a strong reason to change it.
Radia, it is not possible to enumerate primarily because of link
aggregation because of which you can get various speeds.
> And, is it always obvious to a zero configuration Rbridge what speed
> each of its ports is?
> Donald Eastlake wrote:
>> I'm thinking that something like this should be added to item 1 in
>> section 18.104.22.168 of the base protocol draft version -13:
>> To facilitate efficient zero configuration operation, RBridges SHOULD,
>> by default, set the cost of a link to one trillion (1,000,000,000,000)
>> diviided by the RBridge port's bit rate rounded to the nearest value
>> that will fit in the wide metric; for example, the cost for a
>> link accessed by a 1Gbps port would default to 1,000. However, the
>> cost MAY, by default, be increased if the link appears to be a bridged LAN.
>> Donald E. Eastlake 3rd +1-508-634-2066 (home)
>> 155 Beaver Street
>> Milford, MA 01757 USA
>> d3e3e3 at gmail.com
>> rbridge mailing list
>> rbridge at postel.org
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> rbridge at postel.org
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