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New Contributor
Posts: 2
Registered: ‎12-09-2005

Two trunk masters won't merge

Hello,

I'm trying to set up trunking between a 5300 and 6520 using lw gbics and singlemode fibre. We have this working with a number of other switches. I have two links, for some reason I'm getting two trunk MASTERs rather than a master and a member:

b6520-urbna:FID128:admin> trunkshow

  1:  0-> 76 10:00:00:05:33:d8:75:22  32 deskew 15 MASTER

  2:  1-> 77 10:00:00:05:33:d8:75:22  32 deskew 15 MASTER

and at the other end:

b5300-kora:admin> trunkshow

  1: 76->  0 10:00:00:27:f8:9d:d2:cd  34 deskew 15 MASTER

  2: 77->  1 10:00:00:27:f8:9d:d2:cd  34 deskew 15 MASTER

  3: 79-> 28 10:00:00:05:1e:d6:f8:89  30 deskew 15 MASTER

     78-> 31 10:00:00:05:1e:d6:f8:89  30 deskew 15

trunkdebug gives the same vague answer on both switches:

b6520-urbna:FID128:admin> trunkdebug 0 1

port 0 and 1 can't trunk due to one of the following reasons:

ports are not same speed or valid speed

ports are not same long distance mode

local or remote ports are not in same port group

difference between links length is greater than allowed

I've checked the configs for all the ports involved:

  • They're all portSpeed: N8Gbps

  • They all have Long Distance            OFF

  • The deskew for all is 15, which is the minimal value

  • If I understand port groups correctly, they're in the same group on the switch (ports 0,1 on the 6530 ; ports 76, 77 on the 5300).

I came across another discussion of this but it didn't have a solution. I'd greatly appreciate any help.

Thanks

Contributor
Posts: 27
Registered: ‎10-05-2011

Re: Two trunk masters won't merge

I would say that the distance is not equal over the links.

For trunking, the delay of all trunken links have to be (nearly) the same

Uli

New Contributor
Posts: 2
Registered: ‎12-09-2005

Re: Two trunk masters won't merge

This was the solution. I didn't think it would make that much difference (I can't imagine the distances are that different), but with both links of the fabric going the same route the trunks are working. Many thanks.

Rich

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