Peer-Keepalive Link And Messages - Cisco 7206 - VXR Router Configuration Manual

Chapter 7 Configuring vPCs
S e n d d o c u m e n t c o m m e n t s t o n e x u s 7 k - d o c f e e d b a c k @ c i s c o . c o m
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We recommend that you configure Unidirectional Link Detection (UDLD) on both sides of the vPC peer
link. See the
UDLD.
Configuring Layer 3 Backup Routes on a vPC Peer Link
You can use VLAN network interfaces on the vPC peer devices to link to Layer 3 of the network for such
applications as HSRP and PIM. However, we recommend that you configure a separate Layer 3 link for
routing from the vPC peer devices, rather than using a VLAN network interface for this purpose.
Note Ensure that you have a VLAN network interface configured on each peer device and that the interface is
connected to the same VLAN on each device. Also, each VLAN interface must be in the same
administrative and operational mode. For more information on configuring VLAN network interfaces,
see
If a failover occurs on the vPC peer link, the VLAN interfaces on the vPC peer devices are also affected.
If a vPC peer link fails, the system brings down associated VLAN interfaces on the secondary vPC peer
device.
Beginning with Cisco NX-OS Release 4.2(1), you can ensure that specified VLAN interfaces do not go
down on the vPC secondary device when the vPC peer link fails.
Use the dual-active exclude interface-vlan command to configure this feature.
Note When you attach a Layer 3 device to a vPC domain, the peering of routing protocols using a VLAN also
carried on the vPC peer link is not supported. If routing protocol adjacencies are needed between vPC
peer devices and a generic Layer 3 device, you must use physical routed interfaces for the
interconnection. Use of the vPC peer-gateway feature does not change this requirement.

Peer-Keepalive Link and Messages

The Cisco NX-OS software uses the peer-keepalive link between the vPC peers to transmit periodic,
configurable keepalive messages. You must have Layer 3 connectivity between the peer devices to
transmit these messages; the system cannot bring up the vPC peer link unless the peer-keepalive link is
already up and running.
We recommend that you associate the vPC peer-keepalive link to a separate VRF mapped to a Layer 3
Note
interface in each vPC peer device. If you do not configure a separate VRF, the system uses the
management VRF and management ports by default. Do not use the peer link itself to send and receive
vPC peer-keepalive messages. For more information on configuring VRFs, see the Cisco Nexus 7000
Series NX-OS Unicast Routing Configuration Guide, Release 5.x.
OL-23435-03
HSRP active—If you want to use HSRP and VLAN interfaces on the vPC peer devices, configure
the primary vPC peer device with the HSRP active highest priority. Configure the secondary device
to be the HSRP standby. And ensure that you have VLAN interfaces on each vPC device that are in
the same administrative and operational mode. (See the
page 7-25 for more information on vPC and HSRP.)
"Configuring the UDLD Mode" section on page 2-39
Chapter 4, "Configuring Layer 3 Interfaces."
Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide, Release 5.x
Information About vPCs
"vPC Peer Links and Routing" section on
for information on configuring
7-11