Help With Core Nexus Network Design

brianjaus · ‎08-11-2011

Help ! I am a noob network engineer thrown into a project were the real network engineer is out for weeks with bad flu. I am trying to pick up the pieces and do the best design I can. I put this drawing together based on what info I had. The picture shows the basics. It is a large lab scenario with three different building. The core is Nexus. The original engineer had made recommendations and I am not sure I understand them. I understand the usage of the 3 VDCs, and the VPCs to the 4900s. This seems to avoid the need for Spanning Tree in that segment, but I will still have loops below as I believe the three 4900s are actually in a mesh, and the rack and aisle switches will have redundant connections. So instead of Spanning Tree would I use TRILL ? If so where is the TRILL implemented. I understand that the participating TRILL devices will communicate and then encapsulate the packets with a TRILL header. Which devices would be TRILL enabled and participating ? Also how do I segregate or border myself from production ? The original engineer recommended the 5000 layers at the top to control traffic to production as well as provide Layer 2,3 services. Is this necessary ? What is the best way to control traffic at that layer so I can get to production if I want and vice versa but only based on conditions I see fit. Also do I need the 4th VDC for anything ? And do you typically leaved VDC1 alone as the deafult and use 2,3,4.. etc ? Any help would be appreciated.

brianjaus · ‎08-11-2011

And one more question, how do I layer in the SAN. I will have to support FC, FCoE, and iSCSI. Should I use something like a 3750 with FC and Gig connections ?

Jerry Ye · ‎08-12-2011

First, I don't see a loop in the diagram on the 4900s south bound to the 3560s. If you are talking about north bound, it is not a loop when vPC is working correctly. It will see the Nexus as a single device.

TRILL is not available on the Nexus platform yet. The current Cisco implementationis Fabric Path, it is available on the N7K.

I am only assuming your Catalyst 5000 (???, I hope you mean Nexus 5000) as the core. The N7K will still be your aggregation and it should be the L2, L3 boundary.

I will suggest you to leave VDC1 alone and use VDC2 - 4 on your design. It is because configuration on VDC1 can affect all the VDC.

For SAN, you can't use 3750. If you are talking about FC, you need N5K and home it back to your SAN fabric (MDS).

Regards,

jerry

brianjaus · ‎08-12-2011

Jerry,

Thank you so much for the response !! :-)

The drawing is a bit flawed, the 4900s are actually more in a mesh configuration with multiple links between them. I understand that north of the 4900s there are no loops but I am certain there are lots in the 4900 layer and southbound. With the 7000s not yet supporting TRILL, does that affect me ? It seems that TRILL would be running at 4900s and South. So actual RBridges would be those and not they 7Ks correct ?

If it is not yet supported on 7ks and in this picture TRILL is used at that layer... then I cant use TRILL... back to STP then ?

brianjaus · ‎08-12-2011

Also one more point Jerry, this is a lab environment and the actual nodes could be ANYTHING. I know TRILL requires support and version match throughout the infrastructure. I can assume that what is brought in will not always be that up to date. That to further pushes me to believing TRILL is not the answer for this.

Jerry Ye · ‎08-12-2011

TRILL is not an answer for your design.

The point is, you should clean up your environment before inserting them into the N7K. This is not a simple task and it will require a lot of time and effort.

Regards,

jerry

Jerry Ye · ‎08-12-2011

TRILL is not on any product yet. When it is available, it will be on the Nexus 7000 and Nexus 5000.

Will TRILL affect you, this is a question for yourself. It depends on your requirement. Do you need TRILL currently.

http://www.cisco.com/en/US/solutions/collateral/ns340/ns517/ns224/ns783/white_paper_c11-462422.html

If there are lots of links (mesh) between the 4900s, then you are bridging different VDC together. If this is the case, you should think about clean up first. My position on this is not to bridge VDC in the L2's perspective.

Regards,

jerry