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LACP. PaGP or Static etherchannel recommendation

mvknl
Level 1
Level 1

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:

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/best/practices/recommendations.html#wp1046803

This document does not make an explicit statement about which method is best. Could anyone please help me with this?

1 Accepted Solution

Accepted Solutions

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.

View solution in original post

10 Replies 10

InayathUlla Sharieff
Cisco Employee
Cisco Employee

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

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 I know PaGP is Cisco proprietary and superceded by LACP.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.

glen.grant
VIP Alumni
VIP Alumni

For 6500      

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/best/practices/recommendations.html#wp1046596

For 4500

http://www.cisco.com/en/US/partner/tech/tk389/tk213/technologies_tech_note09186a00800949c2.shtml#pagptoconfig

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.

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.

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.

Hi Inayath,

Could you please explain to me how on mode could cause switching loops? Is this because of misconfigurations?

Thanks.

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.

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

Peter,

Great post explaining a lot about possible loop forming with etherchannels.

Thanks!

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

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