Nexus 5000 with 2000 FEX...100Mbit Ports?

Unanswered Question
Feb 7th, 2010

Hello Cisco Users,

I have a problem with the Nexus 5000 Series when implementing it in a data center. I have some 100Mbit Ports (Servers, ILO Ports), which I can't upgrade to 1GE and have to connect them to the Nexus 5000. As I read, all ports of the 5000 are uplink/downlink ports and the the first eight ports are dual speed for 1GE or 10GE connections. As the Nexus 2000 has only 4x 10GE Uplink Ports, I had the idea to connect two Catalyst 3560 Switches with an GE Uplink SFP connection to the Nexus 5000 as it won't work with the 2000 FEX. Are there any concerns about that scenario? In sum, I would have four FEX  and 2 Catalyst 3560 Switches connected to get the necessary 100Mbit Ports. As I know, I would have only a big Layer 2 systemm then, but the Nexus 5000 is connected to a Layer 3 instance for routing purposes. In a later second step, the Layer 3 Router should be replaced by a Catalyst 6500 or Nexus 7000. There are only 50 servers, so not much traffic.Hope anybody can help me with that issue.

Thanks in advance!

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Reza Sharifi Sun, 02/07/2010 - 12:43

Hello Stefan,

If you have enough funding for this project, instead of 3560 you can get 3560-E switches.  They come with 2 10Gig uplinks and 48 ports copper 10/100/1000  You can then directly connect your Nexus 2000 to the 3560s, this way all your uplinks are 10Gig and only 100 to the servers. Also in the feature if you need to connect a server using 1Gig you already have available ports to do so.



StefanDietrich Sun, 02/07/2010 - 13:07

Hello Reza,

Thanks for response. This is a good hint, as I thought the Nexus 2000 10GE Uplinks could be only used for connecting to the Nexus 5000(host). Because the whole management for the Nexus 2000 relies on the Nexus 5000, aren't there any concerns to connect a Catalyst with 10GE Uplink to the Nexus 2000? As I have to regard the funding seriously, the "normal" 3560 is also be an option as I mentioned before. So, are there any limitations when connecting the 3560 with 1GE Uplink directly to the Nexus 5000?It would be a mix of FEX and Catalyst connecting to the 5000 with 10GE(FEX) and 1GE (3560)...

Reza Sharifi Sun, 02/07/2010 - 13:55

Hello Stefan,

I am not very familiar with Nexus products, but I think you should fine with either 1Gig or 10Gig uplinks.  I just like to keep the speed of the uplinks as consistent as possible.  Also the 3560-E switches have higher backplane speed (64Gig) versus the none E switches have only a 32Gig backplane speed, in case you need to add more servers with higer speed down the road. In addition with E models you still have the flexibility to have 4 1Gig or 2 10Gig uplinks. (more flexible).  Of course if funding is not an issue!!



tdistlists Mon, 04/05/2010 - 14:31

Sorry to revive a somewhat older post, but the 2K fabric interfaces can only be connected to a 5K. Also, the 2K 48 ports are only meant for hosts, as they are incapable of running spanning-tree (so in theory, you could connect a switch to it /w bpdu filter on the switchport, but you wouldn't be able to provide any redundancy).

So I was curious as to if you connected your 3750s to the 5K, and if so, how it turned out.



This is an old post but it may still a doubt for someone. This problem no longer exists. New Nexus 2248 supports 100 Mb ports.

But if you have only 50 servers (let me guess 3-4 ports per server), probably Catalyst 3750 stackable switches are more cost effective, it really depends of your future needs and plans.




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