Etherchannel, ethernet over fiber, 25 miles

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Aug 14th, 2007
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I have done lots of etherchanneling in data centers. But I have never tried it as a failover topology between two sites. In the LAN it works great for the additional bandwidth and for failover. i.e. if one of the *ethernet in the bundle goes out the other members of the etherchannel just keep chugging along.

So imagine site A with Cat2948 2/49 ethernet over fiber to carrier 1 and 2/50 ethernet over fiber to carrier 2. Site B 25 miles away is setup the same. Ports 2/49 and 2/50 are configured as an etherchannel bundle. On the surface it seems like this should work. But might I be missing something perhaps with the two carriers, timing, the distance or other?

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mahmoodmkl Tue, 08/14/2007 - 21:34
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I think it is not going to work.Think it as making a channel on two chassis,which is not possible.i,e we cannot from a channel with the links going to two seprate switches.



mmedwid Tue, 08/14/2007 - 21:51
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Hi Mahmood. In my scenario I'm talking about just two switches - one at each data center.

I realize you can't form an etherchannel if the fiber connections terminated on two different switches at one or both of the sites.

Pavel Bykov Wed, 08/15/2007 - 03:41
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In theory this should work. Is connection to your carrier a DarkFiber, or other type of Layer 1 service?

mmedwid Wed, 08/15/2007 - 07:31
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The hand off at each end is fiber to a switch that is provided by the carrier. That switch then connects into the carrier's fabric and terminates at the far side with another switch. The single circuit which is already in place behaves just like any LAN GigE over fiber connection in a data center. So I think adding a second similar circuit (via another carrier) will behave no differently.

mmedwid Thu, 08/16/2007 - 21:47
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I spoke to the carrier. The answer is "it depends". One carrier AT&T passed through all layer 2 information. The other Qwest/Onfiber did not pass on BPDUs etc to the far side.


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