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June 3rd, 2013 04:00

Need to create a dual channel portchannel from a single ISL, preferably non disruptive

Hello there,

I'm facing the following challenge: I have 2 Cisco MDS9222i switches connected over a single ISL and I need to expand the link to a two channel portchannel. If possible I'd like to do this non disruptively.

I was thinking of doing it like this:

  1. insert the new SFPs in both switches
  2. create a new portchannel between the new SFPs
  3. disable the old ISL
  4. add the "old" SFPs to the new portchannel

As far as I can remember creating a portchannel is disruptive, so going directly from a single ISL to a 2 channel portchannel seems not the way to do this. Any tips?

2 Intern

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20.4K Posts

June 3rd, 2013 04:00

setup new port-channel that consists of new ports only, once that is online add existing ISL ports to this port-channel. Yes the old ISL ports will be disabled when you add them to the channel but port-channel is still online. Once you add them go ahead and "no shut" and you are in business.

2 Intern

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5.7K Posts

June 3rd, 2013 04:00

And the most important question: will traffic be disrupted?

2 Intern

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20.4K Posts

June 3rd, 2013 04:00

i have had mixed results, in one instance PowerPath did complain that it lost connectivity but it quickly re-established it. In another instance i did not get anything from SRDF, it kept on running. What's going over the link, MirrorView traffic ?

2 Intern

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5.7K Posts

June 3rd, 2013 05:00

Yep, MV exclusively!

An alternative is to admin fracture, create the portchannel and synchronise the groups again.

2 Intern

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5.7K Posts

June 3rd, 2013 06:00

I have mixed feeling about that, as far as I've seen is that LUNs aren't tresspassed and eventually a mirror group gets system fractured. I haven't seen LUNs tresspassing to the other SP if a MV connection (briefly) fails. And during the time between failing a path and system fracturing the hosts using the primary LUNs will notice delays, so I don't want to do that.

I already wrote an RFC saying the creation of the portchannel will be disruptive and that I will admin fracture all mirror groups. I don't want to take any chances.

2 Intern

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20.4K Posts

June 3rd, 2013 06:00

what if you do one fabric at a time, does MV handle failover properly ?

2 Intern

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20.4K Posts

June 3rd, 2013 07:00

i have no experience with MV, like you said better safe than sorry.

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