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Community Member

OC-12 ATM on CAt 6509

I am designing a GIGE network that is interfacing with an ATM device that is connected to an OC48. My problem is what can Cisco offer in my design to combat the problem of a gig lan then going out of an OC12 pipe. This could be a bottle neck with all the images we have. Is there a way to load balance the atm links.

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Gold

Re: OC-12 ATM on CAt 6509

Rod,

In theory, the only way you can avoid the Gigabit Ethernet network bottlenecking in one OC-12c pipe, is to aggregate two OC-12c connections. Gigabit Ethernet-to-ATM bridging should be able to accomplish the load balancing; I have done this with another vendor's switches, but I have no experience doing it with Cisco's 6509. (Even then, I don't think that customer ever actually generated a whole OC-12 pipe's worth of traffic at any given time, though both OC-12's were active.)

I guess it also depends what you're connecting to: some GigE ports get throttled down to around 600Mbps bandwidth by the hardware, to interface better with OC-12c. The only way to get full-duplex GigE speed I think is to point it into an OC-48c. I've done this with a Cisco ONS 15454; but this customer was being capped at 300Mbps feeding into the GigE by their Internet2 provider.

Do you have any other choices besides an OC-12, like dark fiber, or a GigE-based or WDM-based service provider? What kind of pictures are you moving, and how is it getting done now?

I built a GigE network over dark fiber for a health care system two years ago, that moved a lot of X-ray images from four hospitals across the fiber to a central storage area. The systems doing the X-rays had no better than Fast Ethernet connectivity, so we never ran out of bandwidth on the GigE backbone. I think that even with a Gigabit Ethernet NIC in a machine, you're not going to pump more than 400 to 600Mbps out of it, tops.

Hope this helps.

Cisco Employee

Re: OC-12 ATM on CAt 6509

One option you have is to put several OC12 modules in your chassis and then use spanning-tree parameters to do VLAN load-balancing as described at the following URL: http://www.cisco.com/warp/customer/473/15.html

Gold

Re: OC-12 ATM on CAt 6509

Frederic,

If you put two OC-12 modules in the chassis, can they be configured to be NNI connections, and have ATM automatically load-balance across both links to the ATM device that connects to the OC-48? If yes, I guess it depends on whether that device can do NNI also. Or, is there something else that limits us to just doing VLAN load-balancing per the hyperlink you provided?

Rod,

What kind of ATM device is it that attaches to the OC-48? Who makes it?

Community Member

Re: OC-12 ATM on CAt 6509

It would be a Marconi ASX 4000

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