Руководство По Проектированию для Cisco Cisco Nexus 5010 Switch
Design Guide
© 2010 Cisco Systems, Inc. All rights reserved. This document is Cisco Public Information.
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vPC Member Port Failure
If one vPC member port goes down, it is removed from the PortChannel without bringing down the virtual
PortChannel entirely. Conversely, the switch on which the port went down will properly unmask this vPC number
when sending frames over the peer link (recall the vPC duplicate avoidance technique) in order for the vPC peer to
forward the traffic to the remaining vPC member port. The Layer 2 forwarding table on the switch that detected the
failure is also updated to point the MAC addresses that were associated with the vPC port toward the peer link.
PortChannel entirely. Conversely, the switch on which the port went down will properly unmask this vPC number
when sending frames over the peer link (recall the vPC duplicate avoidance technique) in order for the vPC peer to
forward the traffic to the remaining vPC member port. The Layer 2 forwarding table on the switch that detected the
failure is also updated to point the MAC addresses that were associated with the vPC port toward the peer link.
vPC Peer Link Failure
The following happens when the peer link fails:
●
The operational secondary vPC peer (which may not match the configured secondary because vPC is
nonpreemptive) brings down the vPC member ports, including the vPC member ports located on the fabric
extender in the case of a Cisco Nexus 5000 Series design with fabric extender in straight-through mode.
nonpreemptive) brings down the vPC member ports, including the vPC member ports located on the fabric
extender in the case of a Cisco Nexus 5000 Series design with fabric extender in straight-through mode.
●
On the Cisco Nexus 7000 Series, the secondary vPC peer brings down the vPC VLANs SVIs, that is, all SVIs
for the VLANs that happen to be configured on the vPC peer link, whether or not they are used on a vPC
member port.
for the VLANs that happen to be configured on the vPC peer link, whether or not they are used on a vPC
member port.
●
On the Cisco Nexus 7000 Series, the primary vPC peer brings down the SVI for vPC VLANs for which there is
no forwarding vPC member interface.
no forwarding vPC member interface.
Note: To keep the SVI interface up when a peer link fails, use the command dual-active exclude interface-vlan.
Cisco Nexus 7000 Series Example
Figure 13 illustrates what happens during vPC peer link failure for vPC ports. Agg1 is the vPC primary and Agg2 is
the vPC secondary.
the vPC secondary.
The sequence of events is as follows:
1. The vPC peer link fails, but Agg1 and Agg2 can still communicate via the routed path with the vPC peer
keepalive protocol
2. Ethernet 2/9 and 2/10 on Agg2 are brought down because they are part of vPC Po51 and Po52 respectively and
Agg2 is the operational secondary vPC device.
3. SVI VLAN50 (vPC-VLAN) is brought down on the operational secondary device in order to prevent traffic from
the core routers from reaching the vPC secondary device where the vPC ports are shut down.