Nexus 2K with HP 5900

[aali]

Is it possible to connect HP 5900 switches with Nexus 2000?  I think not, but just want to be sure.

[paulgear]

Hi aali,

I've never used Nexus 2000s, but my understanding is that they are (relatively) dumb port extenders with a proprietary interface.  It seems very unlikely that they would ever work with non-Cisco gear.

[Fredrik Lönnman]

Depends on what you mean. Can you use the HP5900 as an upstream parent switch to the 2K? - no.

Can you connect a HP5900 switch to the downstream facing ports of the 2K? - sure. BUT, remember that the 2K doesnt run spanning-tree so this is NOT RECOMMENDED. However, it will work.

[aali]

Hi Fredrik,

Well, basically the customer has a Tier-3 Nexus Architecture with Nexus 2K/5K/7K.  2K connects to Server Farm and then uplink to 5K (VPC) and then 5K (VPC) to 7K.

They are pretty impressed with HP 5900s and if they can provide connectivity to 2K then may look into it.

so, instead of buying Nexus 2K, they are thinking of purchasing HP 5900 that they  can connect to 2K, so 5900 can communicate with the whole network.

I am meeting them on Monday to get more detials.  one of the suggestions I gave him is that why do we need to connect 5900 to 2K, we can connect 5900 directly to Nexus 5K meaining that both Nexus 2K and HP 5900 will be in parallel communicating to Nexus 5K.

In case, if they do require HP 5900 to connect physically to 2K, I am still confused  How?  I thought as Paul mentioned that Nexus 2K are just  dumb Fabric Extenders and totally depend on Nexus 5K to make decisions.  

[Fredrik Lönnman]

Yeah I see no point connecting HP5900 to N2k to N5k to N7k. If you intend to use 5900 as the access layer, use it instead of the 2K. If you intend to use it as the aggregation layer use it instead of the 5K.

And Paul is absolutely right, the 2K is just like an remote linecard to the 5K. That doesnt mean that you cant connect another switch to it though, but I dont see whats to gain by doing so here.

[aali]

I agree it doesn't make sense and that is why I am going to discuss with them.

Just for my knowleadge, so it is possible to connect Nexus 2K with HP 5900.  Can I take (2) 10GbE Ports from Nexus 2K to HP 5900 and configure LACP between them as a trunk link to carry multiple VLANs?

[Fredrik Lönnman]

If its downstream facing (host) ports, yes  (you'll need 2232-series N2K for 10G host ports). This is like connecting the N2K to whatever, its nothing special about the 5900 in this regard.

HOWEVER, the N2K DOESNT RUN SPANNING-TREE. Actually it has bpduguard in hardware and it cant be disabled. This might make running the N2K to another switch a Bad Idea (tm), but depending on your design this may or may not be a problem.

Keep in mind that the N2K is designed for host connectivity.

And, if this wasnt clear before, you cannot connect the fabric interfaces on the N2K to the HP5900 in any way, those needs to be connected to the parent N5K or N7K.