WAN link on nexus5k

[satya mothukuri]

Hello,

We are having two Data centers A and B. A has 2 No's 5672 and B has 2 No's 9372. we are planning to connect both DC's using point to point 10 Gb link. Now coming to the problems.

1. Since i have only 1 physical connection (10Gb), i would like to terminate directly on the one of core nexus on both sides.

  I would like to know what problems i will face, if i directly connect the WAN link on core nexus? other than redundancy.

2. If its not advised to connect WAN on Core nexus, Can i terminate WAN link on WS-C3650-24TD , which has 10Gb interface and then connect to nexus .Since i don't have router which has 10Gb interface(4351 i have). I am planning to run BGP here for the WAN routing.

Please suggest which is better approach.

Thanks,

Satya  

[Francesco Molino]

Hi

The wan link is a P2P which means a private link (e.g dark fiber).
Except redundancy, you can connect it to your nexus devices and run bgp. You will need to have the correct licenses: essential on N9k and LAN_ENTERPRISE_SERVICES_PKG on N5k.
Except that, no issues.
On your 3650, you'll need IP Services to run BGP. And you will need to interconnect it with your nexus in L3 to route the traffic.

If this link P2P is a dark fiber or a L2 link, you can connect it to your 3650 into a vlan and span this vlan down to your nexus to have the full redundancy on both nexus switches but the SPOF will be your catalyst.

It will be a question of license first and risk vs redundancy.

[satya mothukuri]

Thanks for the reply.

1. Yes we got private link, and nexus has INCREMENT LAN_ENTERPRISE_SERVICES_PKG on 5k. Just want to know if there will be any issue if the service provider will cause any flooding and also on the performance.

2. on Switch, we have the lic. I want both sides to have switch and have /30 on a (10Gb)switch port. May be static routes towards wan and dynamic towards Nexus(just to reduce load on switch). I didnt get how redundancy work here?

So two cable should connect to 2 5k's and establish routing between them?

[Francesco Molino]

Performance issue on Nexus or 3650 will depend on the actual status. But adding a link with dynamic protocol like BGP won't impact too much, and again it depends on the bgp table that'll be exchanged.

What do you mean by you have a /30? If this is a private L2 link you can decide what subnet you want to put in place.
If you want to have kind of a redundancy:
1. Connect the physical link on your 3650 and place it on a vlan let's say 10
2. This 3650 is attached to your Nexus over a Vpc that will trunk this vlan 10.
3. You can create a vlan 10 on both Nexus that will do bgp with remote end.
Between the 2 Nexus, you can either have a dedicated L3 link for intra peering between Nexus or leverage the VPC to do routing. I won't discuss here if dedicated is better than vpc or the invert. Here an official doc saying what links are supported: https://www.cisco.com/c/en/us/support/docs/ip/ip-routing/118997-technote-nexus-00.html#anc2

Or to keep it simple, you can do L3 on the 3650 (static or dynamic).

In any design, as you have all licenses to do all of them, the spof will be that you have 1 link only.