11-22-2012 03:18 AM - edited 03-07-2019 10:12 AM
Hi All,
A while ago I red somewhere that the recommended way to create portchannels is to use the static 'on' configuration. However, I'm not able to find this information anymore. Does anybody here have a reference to the recommended way to configure portchannels?
I've found the following document:
This document does not make an explicit statement about which method is best. Could anyone please help me with this?
Solved! Go to Solution.
11-22-2012 04:06 AM
Hi Michael,
I would stay away from ON mode in chanenling, alot of the time it leads to switching loop.
On the other hand, PAGP/LACP allows dynamically negotionation of etherchannel one being propietary and the other open standard. Even LACP allows active/standby by bundling multiple links and using some of them but the others are in standby mode incase any member channel fails.
I am not quite sure if this is recorded anywere that you need to use LACP over PAgp or Pagp over LACP.
If bundling between cisco devices then we prefer to use the Pagp as thats cisco proprietary.
Regards,
Inayath.
11-22-2012 03:31 AM
Hi Michael,
It really depends which way you want to configure the etherchannel.
There are 2 ways:
1) Dynamically negotiated and
2) Manually. (PAGP/LACP) ---Pagp is cisco proprietary protocol were as lacp is open standard. And many likes to prefer to go with LACP.
Channel mode "on" means neither LACP nor PAgP; rather, it means simply "EtherChannel" or "Link aggregation". No dynamic signalling is present but still it is the mechanism of bundling several links together.
Syntax:
SW1(config-if)#channel-group 1 mode (Here you have options to chose what you want to do, either on/auto/pasive/desirable)
SW1(Config-if)#channel-protocol pagp/lacp ( this commands will enable you to chose the protocol which you want to configure).
Link for more information :
http://www.cisco.com/en/US/tech/tk389/tk213/tech_configuration_examples_list.html
HTH.
Regards
Inayath
11-22-2012 03:35 AM
Yes, but isn't there a statement from Cisco stating the way they would like you to do it? I know PaGP is Cisco proprietary and superceded by LACP. So LACP would have preference over PaGP, but how about a static on configuration?
In other words, does LACP have specific benefits over the static configuration or the other way around? I would imagine a static configuration to be faster as it does not need to negotiate.
11-22-2012 03:59 AM
For 6500
For 4500
Myself I have always used pagp between "cisco" devices , if etherchanneling to other devices then obviously you cannot use pagp. I have never had any issues using papgp and it's extremely stable.
11-22-2012 04:04 AM
Hi Glen,
I've found that document as well, however, there's no real recommendation in it concerning the mode that should be used. It only states that whatever mode you use, you must use it consistently.
11-22-2012 04:06 AM
Hi Michael,
I would stay away from ON mode in chanenling, alot of the time it leads to switching loop.
On the other hand, PAGP/LACP allows dynamically negotionation of etherchannel one being propietary and the other open standard. Even LACP allows active/standby by bundling multiple links and using some of them but the others are in standby mode incase any member channel fails.
I am not quite sure if this is recorded anywere that you need to use LACP over PAgp or Pagp over LACP.
If bundling between cisco devices then we prefer to use the Pagp as thats cisco proprietary.
Regards,
Inayath.
11-22-2012 04:10 AM
Hi Inayath,
Could you please explain to me how on mode could cause switching loops? Is this because of misconfigurations?
Thanks.
11-22-2012 04:20 AM
Hi Michael,
Yes you are right. You need to be very carefull while configuring "on" mode, make sure the parameters are matching properly and there is no one doing changes at one side and leaving the other by mistake.
Hope this helps.
Plz rate if this is helpfull.
Regards,
Inayath.
11-22-2012 04:29 AM
Hi Michael,
You may be interested in reading this thread. It is a very lengthy debate of how a switching loop is created with misconfigured EtherChannels running the "on" mode but I guess it is relevant to what you are asking about.
https://supportforums.cisco.com/message/3241966#3241966
Oh, and I personally always prefer LACP and go with the "on" mode only if there is absolutely no other alternative.
Best regards,
Peter
11-22-2012 05:22 AM
Peter,
Great post explaining a lot about possible loop forming with etherchannels.
Thanks!
11-22-2012 06:38 AM
Was the Cisco info you read in relation to VMware perhaps: -
"On the ESX host, the vSwitch IP-based load balancing does not run the 802.3ad LACP. For this reason, the EtherChannel configuration on the Cisco Catalyst switch can not use dynamic negotiation, which means that the channel-group is set to ON in the configuration."
http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/vmware/VMware.html
Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: