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Author Topic: MLT question - can you mix Fiber and Copper?  (Read 3945 times)

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Offline Gipper

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MLT question - can you mix Fiber and Copper?
« on: May 06, 2013, 12:38:36 PM »
Hi All, is it possible to combine Fiber (SFP) and copper ports into the same MLT Group?  I tried doing this and received the following error > "Trunk members must do rate limiting the same way".  I see that there is a rate limiting option, but I never changed this setting on any ports so I figured I'd ask if this is even possible before chasing this any further.  If it matters, I'm trying to use ports 48, 49, 50 on an ERS 4850GTS.  Port 48 being copper and 49 and 50 being SFP Fiber, all running at 1Gbps. 

Thanks! 


Offline Dominik

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Re: MLT question - can you mix Fiber and Copper?
« Reply #1 on: May 06, 2013, 02:16:03 PM »
In general it is no problem to mix copper and fibre ports in a MLT Group.
To build up a MLT Group all ports must have the config.
In your case check the rate limiting configuration and configure both ports with the same settings.

Good Luck
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Offline Telair

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Re: MLT question - can you mix Fiber and Copper?
« Reply #2 on: May 06, 2013, 05:26:55 PM »
You are free to use fiber and copper in your MLT groups as long as they are the same speed.  So 1 Gig fiber and 1 Gig copper are fine to use together ( and I do use that exact config in a few places ).  Just don't put 1Gig fiber and 100Mb copper or 10Gig fiber with 1Gig fiber together.

Offline Paul L

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Re: MLT question - can you mix Fiber and Copper?
« Reply #3 on: May 06, 2013, 05:43:51 PM »
there was a time when it wasn't supported.  (or at least frowned upon by Nortel support and Sales Engineers)    :)

But as mentioned above, you will be good to go.

 
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Offline Dominik

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Re: MLT question - can you mix Fiber and Copper?
« Reply #4 on: May 07, 2013, 09:23:14 AM »
@Telair
It makes no sense, but you can mixup on the ERS4k and 5k 1Gig and 100Mbit Interfaces in a MLT.
As far as I know only on the ERS8k the switch will not allow to mix up differrent port speeds in a MLT trunk.
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Offline Telair

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Re: MLT question - can you mix Fiber and Copper?
« Reply #5 on: May 07, 2013, 04:21:38 PM »
That's crazy...  Why would they even allow that?  Sounds more like something they overlooked that will be fixed in a future release.

Offline Johan Witters

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Re: MLT question - can you mix Fiber and Copper?
« Reply #6 on: May 07, 2013, 06:06:25 PM »
As far as I know there is no longer any issue with mixing different media types in a MLT. The last few years have not run into any problems mixing coper and fiber.

There are a number of scenarios in which it is possible to mix different speeds in 1 MLT without the system generating an error, but in all manuals I've read Nortel and Avaya have explicitly mentioned NOT to mix different port speeds in the same MLT. The MLT is not speed aware and spreads packets acros the link members based on a hashing mechanism. That leaves the door open for possible overloading of an interface..
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Johan Witters

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BKM NV