Cisco Nexus 5000 Series Operation Manual page 27

Chapter 2 Cisco Nexus 5500 Platform Layer 3 and vPC Operations
S e n d d o c u m e n t a t i o n c o m m e n t s t o n 5 k d o c f e e d b a c k @ c i s c o . c o m
MAC address (when FHRP is enabled) or its own MAC address. In this scenario, a Cisco Nexus 5500
Platform switch can forward the traffic to the peer using a peer link and the peer switch performs the
Layer 3 forwarding.
The above scenario often happens with some filers or with Layer 3 peering over vPC. In the case of filers,
they may achieves improved load balance and better performance by forwarding traffic to the
Burnt-in-Address (BIA) of the routers instead of the HSRP MAC.
Figure 2-2
destination MAC, the packets can be sent over to the N5k-2 switch due to the port channel hashing.
Figure 2-2
L3
L2
Another scenario that could lead to this situation is when a router is connected to a Cisco Nexus 5500
Platform in a vPC topology.
Figure 2-3
shows that when the NAS filer sends out packets with N5k-1's MAC RMAC-A as the
vPC and Peer-Gateway
N5k-1
RMAC-A
HSRP
Active
Connecting to a Router in a vPC Topology
VPC Topology
N5k-1 N5k-2
Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Layer 3 Forwarding for Packets to a Peer Switch MAC Address
N5k-2
RMAC-B
HSRP
Standby
L3 Topology
N5k-1
R
N5k-2
2-3