Etherchannel:

[s4sandyad]

Hi,

I want to ask basically two questions regarding Etherchannel:

1) In Etherchannel, PAGP n LACP negotiates for formation n maintenance of links. But while using 'ON' mode exactly what happened. book says no negotiation protocols like PAGP and LACP are used. now my question is in ON mode Etherchannel is formed , maintained & worked properly. ok means formation & maintenance is happed properly in ON mode too then why we need of PAGP or LACP separately. what is difference between ON mode & PAGP/LACP mode exactly.

2) Load balancing in Etherchannel: suppose there are 4 bundled links in between 2 switches. I can use any method of load balancing like source ip, dest ip, mac etc... but by using any method how data is distributed among these 4 links. is there any logic or algorithm or what? or on basis of method of load balancing the way of data distribution among link is changed or what ?

Please guide me on this as well as send me proper links get more knowledge about this.

Thanks,

S@ndy.

[Mark Malone]

Hi

If you use on it doesn't use either protocol it just builds the etherchannel , pagp is cisco own version and lacp is the open standard , using the protocols in the real world can prevent issues and limit problems , i have seen instances of customers setting up etherchannels and using on and cabling it incorrectly causing stp issues as just 1 example causing a loop in the network at layer 2, the protocols can prevent issues as they wont form and come up if something is wrong , in the real world the links could be between buildings patch panels and you are relying on someone on the other side to have everything correct if they dont and you force the etherchannel to bundle with on you could take down the network

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/best/practices/recommendations.html#wp1046596

This  link below explains the load-balance well , when you set it up you should always check the individual links of the member channel and see which links are being used the most from there you can adjust to your specific traffic patterns

http://packetlife.net/blog/2010/jan/18/etherchannel-considerations/