Hello I configured lacp between a cisco switch and a nortel load balancer. Could someone tell me what "default" port means in the cisco output below, and what the effect of this is, i read somewhere its the port where multicast traffic is sent on, i cant find it in any books. I noticed if i change "system priority higer on my switch than the nortel the default port changes to 4, i cant work out why. Thanks for any help Switch#sh etherchannel summary Flags: D - down P - in port-channel I - stand-alone s - suspended H - Hot-standby (LACP only) R - Layer3 S - Layer2 u - unsuitable for bundling U - in use f - failed to allocate aggregator d - default port Number of channel-groups in use: 1 Number of aggregators: 1 Group Port-channel Protocol Ports ------+-------------+----------- +----------------------------------------------- 3 Po3(SU) LACP Fa0/3(Pd) Fa0/4(P)
If I had to guess, the switch is not going to send the same frame to both ports, else there is no point of an etherchannel (it could then only go at the speed of a single port). Therefore, one port has to be the first port which traffic is sent, at which time its alternated or goes to the second port at a certain utilization. I would guess that has something to do with default port...but again...just guessing. Would need to read up on cisco.com.
"The default port is used to transmit traffic, such as Spanning Tree Protocol (STP), multicasts, and unknown unicasts. The default port can be identified from the output of the command show etherchannel summary by a notation of d." more: http://www.cisco.com/application/pdf/paws/12023/4.pdf Best Regards, News Reader
Thats good to know. One thing I have noticed is that the default port can change sometimes from 3-4 (if i reset the switch or change the config) but mostly stays on 3, not sure if this matters. The nortel side refers to this default port on the cisco as "attached aggreagator" Im not sure what this means though - any ideas? thx
No, my contribution was limited to finding you some literature ;>) , since you stated "i cant find it in any books". Other posters will have more familiarity with this subject than moi. Best Regards, News Reader
