7 Replies Latest reply: Sep 14, 2010 11:54 AM by 807567 RSS

    Etherchannel and link aggregation


      I'm a bit confused now, Sun Trunking supports Cisco Etherchannel, but link aggregation doesn't (if I understand correctly, a with the results of my quick tests).

      Sun Trunking seems to be supporting a certain set of drivers and link aggregation another set.

      Right now I've got a T2000 with 4 X e1000g and 4 X nxge, does anyone knows, if I can use these interfaces with Cisco Etherchannel, or do I absolutely need to use LACP with link aggregation??? The problem is that the network guys don't want us to use LACP (for whatever reason they have)...

      Thank you very much.
        • 1. Re: Etherchannel and link aggregation
          I didn't think that etherchannel was different from link aggregation, just that aggregation required a different etherchannel mode ('lacp' mode instead of the standard mode).

          But yes, I think SunTrunking and traditional etherchannel were a de-facto standard of sorts from Cisco, while link aggregation/802.3ad is the newer industry standard and they're not equivalent at the network layer. (apologies, and I hope someone corrects me if I've misstated that).

          Link aggregation supports any GLD3 driver while Sun Trunking supports a particular set of interfaces. There may be some overlap, but yes, the support levels are not the same.

          SunTrunking compatible interfaces are spelled out explicitly in the SunTrunking documentation. I haven't looked at it in a while, but I don't recall those two being supported. They should be GLD3 drivers, though.

          I hope you can convice your network folks that 802.3ad is the "way of the future" or something like that. Good luck!

          • 2. Re: Etherchannel and link aggregation
            Well, from what I've read so far, it's two different ways of doing the same thing.

            I will call Sun support for a confirmation of this, because the network dept. won't do anything without that.

            • 3. Re: Etherchannel and link aggregation
              That's correct. They both split traffic over multiple links.

              How about documentation?

              This page:

              mentions that link aggregation uses the IEEE 802.3ad standard. If your switch conforms to that it should work. If it doesn't, it probably won't.

              Cisco docs on 802.3ad

              • 4. Re: Etherchannel and link aggregation
                At the end I just want to know if it's possible to do pure Cisco Etherchannel with e1000g's and nxge's...

                Thanks again.
                • 5. Re: Etherchannel and link aggregation
                  I don't know any cisco term referring to "pure" etherchannel, so I don't know how to answer that. Both LACP and PAgP are link management protocols that cisco can use. I'm supposing that you're asking if the cards will work with PAgP management, but I'm not sure.

                  This FAQ:
                  suggests that I've been incorrect about 802.3ad being a "new" thing and that SunTrunking 1.3 also uses it.

                  The SunTrunking 1.3 docs here:
                  in chapter 1 (Overview) list six cards. I don't think yours are any of them, so SunTrunking is out.

                  Because LACP "only" manages the link configuration rather than driving the data, it seems to me that both the link-aggregation and cisco sides could work without LACP being present, but the management of the links might be wonky.

                  So without LACP, the links have to be configured manually, but I don't yet see anything that states that the two sides will not communicate if that is done.

                  Further, the 'dladm' man page says that one valid lacp mode on the Solaris is "off", so it must have some functionality without LACP. I would imagine that will required some sort of manual link configuration on the cisco side. (The solaris side is not going to do PAgP).

                  See also:

                  When the www.opensolaris.org boards come back up, I would recommend posting this question in the "networking" discussion group.

                  • 6. Re: Etherchannel and link aggregation
                    Thanks for your answers, I was indeed talking about PAgP.
                    I will ask this question on the OpenSolaris boards as you suggest.

                    In the mean time, we are going to be doing some configuration tests and try the manual way.

                    • 7. Re: Etherchannel and link aggregation
                      Firstly, PAGP is Cisco proprietary so Solaris will not support it. Whilst LACP mode off is valid, it does as it says on teh tin, i.e. that interface won't become a member of the aggregation. You will 4eed to set one end at least to active. I know of an instance with 8 channels between a Cisco 6509 and Solaris using nxge and bge interfaces.