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Community Member

MEC with VSS

Hi ,

we have Core switches 6509E upgraded to VSS , and also in the access have some 3COM switches support LACP, we want to have MEC between the 3com access switch and the two Cisco Core 6509EVSS switches,please advise.

Hall of Fame Super Silver

Re: MEC with VSS

Hello Ahmed,

the VSS will present itself as a single box with a single LACP system-id, you should not have problems in connecting the access layer swiches to it using standards based LACP.


Multichassis EtherChannel Restrictions and Guidelines

When configuring MECs, note the following guidelines and restrictions:

All links in an MEC must terminate locally on the VSS active or VSS standby chassis of the same virtual domain.

For an MEC using LACP control protocol, minlinks defines the minimum number of physical links in each chassis for the MEC to be operational.

For an MEC using LACP control protocol, maxbundle defines the maximum number of links in the MEC across the whole VSS.

MEC supports LACP 1:1 redundancy. For additional information about LACP 1:1 redundancy, refer to the "Understanding LACP 1:1 Redundancy" section on page 17-5.

An MEC can be connected to another MEC on a different VSS domain.

Hope to help


Community Member

Re: MEC with VSS

My concern here is the access switches is not Cisco is 3com/H3C,still can work with cisco VSS 6509 core and creat MEC and can the 3com/H3C switches see the two core 6509E VSS as a one entity.

small question if you do not mind, i am planning to connect the 3com switcheswith 10G SFP+ SR, with Cisco 6509E 16 PORT 10G (Cisco X2 10000BASE SR) ,can both 10G TRANCEIVER from 3com and Cisco connected together in 10 G with these tranceiver?.

thank you in advance.

Community Member

Re: MEC with VSS

Any update Mr

VIP Super Bronze

Re: MEC with VSS

Hi Ahmed,

MEC is only supported when using 3750 switches and that is because they are stackable.  If you are using only one 3Com switch you can simply uplink the 2 10Gigs to 2 different 6509 (VSS in this case) and form standard LACP connection.  But if you are planning to have multiple 3com access switch uplink to VSS, in this case cross chassis or MEC is not supported.   I have only deployed VSS with MEC using Cisco devices and since you are using 3Com, you would need to test it and make sure it works.  Also for dual active detection since your access switches are 3com, you have to use fast hello and can not use PAGP. As for connecting your 10Gig 3Com switch to Cisco 10Gig module you should not have any problem.  Cisco 10Gig connectors for 6500 are all SC.  I do not know what 3Com uses



Community Member

Re: MEC with VSS

Hi ,

thank you,

so what i understood , that if we have one 3com switch dual connected to two core 6509 VSS , the 3com switch will see the two 6509 VSS switches as a one switch?. Please confirm.

Another question if i have two 3com switches running technology like  VSS or stacking ,so the two 3com will be like one unit, and these two 3com switches (virtual one unit)connected to two Core Cisco 6509 not running VSS , each one of the 6509 will see the the 3com switches as one unit or not.

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