Migrating from 1Gb to 10Gb uplinks

Unanswered Question
Aug 23rd, 2007

We are evaluating an upgrade from the current 1Gb backbone to a 10Gb

backbone in a mixed manufacturer environment. This process will begin

with an upgrade to our existing 1Gb core switching platform. If we were

to install WS-X6708-10G-3CXL modules with X2-10GB-LR optics, would this

10Gb configuration throttle back to support existing 1Gb connections to

the network edge until we can eventually upgrade these edge devices to


I have this problem too.
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Joseph W. Doherty Thu, 08/23/2007 - 12:53

If you're asking whether you can have a 10 gig module on one end of the fiber, a 1 gig module on the other, and that the link will run at 1 gig, believe the answer is no.

If I'm correct, what you could do is, assuming you have room in the chassis, is also have and use one of the fiber gig cards, e.g. WS-X6748-SFP, until you change the edge. Also, depending what's on the edge and what your fiber plant is like, you might be able to Etherchannel some of the gig fiber.

nathanlarmore Fri, 08/24/2007 - 08:51

Would this work?

I want to purchase the WS-X6708-10G-3CXL, an 8-port 10 Gigabit Ethernet module equipped with X2 optics for my 6509-E. I've recently looked at the 3750-E as an edge solution and liked it because it could be equipped with a TwinGig Converter module converting the 10 Gigabit Ethernet X2 interface into two Gigabit Ethernet SFPs for migration from 1Gb to 10Gb. Couldn't I use this same converter module in the 10Gb blade for my 6509-E?

avmabe Fri, 08/24/2007 - 09:00

I would not recommend even trying to come up with a way to take a 6708 10Gig card to run with 1Gig optics.

See below:

Q. What optics are available for the 8-port 10 Gigabit Ethernet module at FCS?

A. The following optics are supported on the 8-port 10 Gigabit Ethernet module at FCS:

? X2-10GB-SR: 26m over FDDI grade MMF, 300m over 50-micron 2000 MHz*km MMF

? X2-10GB-LR: 10km over SMF

? X2-10GB-ER: 40km over SMF

? X2-10GB-LX4: 300m over FDDI grade MMF

? X2-10GB-CX4: 15m over 8-pair 100-Ohm Infiniband cable

Only the -02 version or later of the above optics is supported on this 8-port 10 Gigabit Ethernet module. The -01 version of the optics is not supported. This restriction does not apply to X2-10GB-LRM.



Also don't forget you have to have a SUP720 to run this card.

Joseph W. Doherty Fri, 08/24/2007 - 09:48

I thought of that too. Assuming the modules are interchangeable, the biggest problem was a single 3750-E would only support two downstream gig ports on the box with the 10 gig. Sure you could build a stack, but it's an expensive way to add gig ports, four per 3750-E stack member.

If you plan to redeploy the 3750-Es, your not losing on that part of the investment, but your are buying the two gig converters and modules. (Also, if you use 3750-E as an edge device, why not use it's 10 gig port, i.e. why move the module to the 6509?)

What might be a better option, if you have a good relationship with who you're buying equipment from, and you're buying much, inquire about a loaner or buy back option. Often sales will be very helpful obtaining equipment or special deals to help you with a transition.


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