L3 Router connected to Pair of 5500 Series, traffic hitting secondary one instead of primary

[snahosany]

Hello,

I have an issue where traffic going to a pair of nexus (5548UP) is hitting the secondary one instead of the primary one. I have one router dual homed to both nexus via routed ports (runs ospf). Both is connected to a 4500 series switch in vpc. This setup works fine. From a pc behind the 4500 switch, when i ping the router interface connected to Nexus-1, it goes through primary nexus which is Nexus-1. I have dual-homed another router to both nexus with same setup as mentioned above., but now when i ping the router interface connected to Nexus-1 from the PC behind the 4500 series switch, the traffic goes to the secondary nexus. Is this something normal? I want the traffic to hit Nexus-1 since the router interface i am pinging is connected to Nexus 1

Any advice, anything i am doing wrong?

Thanks

[Reza Sharifi]

Hi,

Since the 5ks are running layer-3 with the routers, can you enable "peer-gateway" command on both Nexus and than test again?

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/mkt_ops_guides/513_n1_1/n5k_L3_w_vpc_5500platform.html

Figure-5-3

HTH

[snahosany]

Hello Reza

thanks. I have done so, but still it does not work, it is still going to the secondary nexus. Any ideas?

[snahosany]

In the Document you sent me, my topology looks like figure 5-7. The Router is not VPc'd to the nexus. 

[Reza Sharifi]

Hi,

So, do you have a layer-3 connection between the 5ks as shown in figure 5-7?

[snahosany]

yes. exactly as in figure 5-7

[Reza Sharifi]

So, when you do a trace route from the PC sitting behind the 4500 (layer-2) does it go 5k-2 first and than across the layer-3 link and than 5k-1?

is there HSRP between the 5ks

[snahosany]

when i trace route it goes to 5k-2 and then directly to the router across the Layer 3 link. Yes HSRP between 5k, active on all vlans being the primary nexus.

[Reza Sharifi]

I think the case when VPC is configured on the Nexus.  Even though 5k-2 is backup HSRP, it will still froward traffic upstream and will not send it to HSRP active for forwarding.

HTH

[snahosany]

so you mean the behavior is normal, traffic destined for router interface connected to nexus-1 should be hitting nexus-2? i have same setup for another router and it goes through nexus-1