N7K switches

[S891]

Hi,

What could be potential issues of replacing all N5k/N2K and N3ks and 3750Es with a pair of high port density N7Ks? Currently we have a bunch of these switches in DC. If those are replaced with N7Ks then we can possibly get rid of managing so many DC Access switches. But I am not sure what could be the limitations/considerations for such approach?

[InayathUlla Sharieff]

Hello Fawad,

Couple of things to be looked here:-

1- Were are you planning to place this N7K?

2- If you have bunch are you planning to use this N7K at the access layer as well by using the FEX connecting to it?

3- N7K are powerfull boxes if placed correct it can do wonders. But it all depends on how you want it to be manage.

4- Regarding limiation/consideration- You have to do re-design of the connecting network replacing the existing infrastructure. Things like VPC/HSRP is to be done on this devices are not...how are we connecting the end hosts...etc...

HTH

Regards

Inayath

[S891]

Hi InayathUlla, 

Answers to your question inline..

1- Where are you planning to place this N7K?

    It can be placed as collapsed access/distr in DC. 

2- If you have bunch are you planning to use this N7K at the access layer as well by using the FEX connecting to it?

   Yes, I am thinking of using N7K at Access. I am thinking of getting rid of N2Ks and connect FIs as well as current N2K hosts directly on N7K so basically getting rid of N2Ks.

3- N7K are powerfull boxes if placed correct it can do wonders. But it all depends on how you want it to be manage.

  I am thinking if it is placed like I mentioned above and there is enough 1 gig/10 gig port density available I can get rid of many TOR switches and all FEXs. It will be easier to do upgrade as there is currently issues with FEXs instability during upgrade even with ISSU. 

4- Regarding limiation/consideration- You have to do re-design of the connecting network replacing the existing infrastructure. Things like VPC/HSRP is to be done on this devices are not...how are we connecting the end hosts...etc...

Yes, there will be redesigning involved. End hosts will have dual connection to each N7K. Layer 3 will also be configured on N7ks. I am also thinking of creating VDCs (one connecting to northbound Core and one VDC for DC Layer 2 and Layer 3) and passing the traffic between VDCs through an ASA pair. 

[avvotyakov]

Most issue in n7k, that if you work with vPC construction, you can't use thay like l2 and l3(with svi interface), for l3 you must use separate port. second issue if you work with f2/f2e card have limitation in 16k mac addres for all vpc vlan, on level 13.5k mac addres n7k start some problem

[S891]

Sorry, I didn't get your comment about L2 and L3. Are you saying we cannot have SVIs in this ocnstruct?

[avvotyakov]

Read this book

http://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/sw/design/vpc_design/vpc_best_practices_design_guide.pdf

[S891]

I think if I get rid of FEXs and just use N7k as access and distribution (L3) collapsed in DC it would still work. There will be some limitations as compared to having another Access Layer with N2Ks and N5Ks but I think for mid-size setup this should still work. 

In the Cisco document below this is referred as Single-sided vPC. 

http://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/sw/design/vpc_design/vpc_best_practices_design_guide.pdf

I also learnt from SE that for FCoE I will have to use a separate VDC.