Руководство По Проектированию для Cisco Cisco Nexus 5010 Switch

 

 

Design Guide 

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Figure 15 shows the case in which device A sends traffic to remote MAC (RMAC) address A with a PortChannel hash 

that forwards the traffic to switch B. The result is that the frame cannot get to server B because of the duplicate 

prevention rule. 

Figure 15.    The problem addressed by the peer-gateway feature 

 

To address this forwarding scenario, you should configure the peer-gateway command under the vPC domain. This 

command enables the vPC peers to exchange information about their respective BIA MAC addresses so they can 

forward the traffic locally without having to send it over the peer link. 

In vPC designs, you should make sure to include a Layer 3 link or VLAN between the Layer 3 switching vPC peers so 

that the routing areas are adjacent. Also, you can consider HSRP tracking in non-vPC designs, but not in vPC 

designs. 

HSRP tracking is not recommended for the reasons illustrated in Figure 16. Imagine that traffic from n5k on VLAN60 

needs to be routed to n5k on VLAN 50. As a result of a core link failure, HSRP tracking shuts down switch virtual 

interface (SVI) 60 on Agg2 and forces the VLAN60-to-VLAN50 traffic to Agg1. Agg1 routes from SVI 60 to SVI 50 and 

then forwards to Po52 to reach n5k. vPC prevents this forwarding behavior as previously explained. 

Because of this behavior, you should create a Layer 3 path on the peer link between the routing engines on Agg2 and 

Agg1 instead of using HSRP tracking.