Metro-Ethernet connection not coming up at Head end

Unanswered Question
Dec 3rd, 2009

We recently implemented ME (from AT&T). The head-end and four (4) remote ends are connected. Head-end is 50MB and each remote end is 8MB. The head-end is a SM 100/FULL hand-off. The remotes are coper hand-offs. AT&T tells us to hard setp each location (head and remotes) to 100/FULL. The problem is at the head-end we are connecting to a router SFP (sm) which will only perform 1000 auto or you can do non-negotiation. The remote locations can see each other via CDP, but the head-end to the remote. The head-end will not come up since we are not able to hard set the sfp tp 100/FULL. Instead we are using a SM transciever fo media conversion, but still having no success. The media converter has been swapped to rule out as a possibility and the dip switches on the convertor are set correctly. Could this be a provider issue. The config is attached.


I have this problem too.
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Giuseppe Larosa Thu, 12/03/2009 - 12:26

Hello Mbroberson1,

SFP are full duplex for their nature: almot all have two fibers one for TX and one for RX.

the problem is that you cannot set the speed also.

You should check with provider people if you need to use another transceiver: there are speciall SFP that can be inserted in a Gigabit port SFP slot and that actually works fixed at 100 full we are using them in some small campuses to interconnect new switches to old fiber based FE links.


100 Mbps SFP

to connect to a GE port you need to use a GLC-GE, there are others that can be used with FE ports

1000 Mbps SFP

Hope to help


mbroberson1 Thu, 12/03/2009 - 12:31

Hi giuslar,

Not sure if I mentioned this. The head/end device is a 3825 router and remotes are 2821 routers. We are using the g0/0 slot on the 3825 (head-end where we are having the issue)  which has sfp capability.


Reza Sharifi Thu, 12/03/2009 - 12:56


the 3825 comes with 2 on board copper 10/100/1000.

Can you use the media converter to go from ATT fiber to the fiber side of media converter and then copper from media converter to your 3825 copper port?



mbroberson1 Thu, 12/03/2009 - 13:08

We found the issue. We had the circuit tested and found out we needed to use MM and not SM on the head-end. We were told it was SM all along until now. The links to all sites came up after changing over to MM.



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