Vpc Domain; Peer-Keepalive Link And Messages - Cisco AP775A - Nexus Converged Network Switch 5010 Configuration Manual

vPC Domain

The Cisco Nexus 5000 Series switch can support up to 12 configured dual homed Fabric Extenders with this
topology. A maximum of 480 single homed servers can be connected to this configuration.
vPC Domain
You can use the vPC domain ID to identify the vPC peer links and the ports that are connected to the vPC
downstream switches.
The vPC domain is a configuration mode that you use to configure the keepalive messages and also configure
other vPC peer link parameters rather than accept the default values.
To create a vPC domain, you must first create a vPC domain ID on each vPC peer switch using a number
from 1 to 1000. This ID must be the same on a set of vPC peer devices. Within this domain, the system
provides a loop-free topology and multipathing.
You can configure the EtherChannels and vPC peer links by using LACP or no protocol. When possible, we
recommend that you use LACP with the interfaces in active mode to configure EtherChannels in each vPC
to ensure an optimized, graceful recovery in a port-channel failover scenario and provides configuration checks
against a configuration mismatch among the EtherChannels.
The vPC peer switches use the vPC domain ID that you configure to automatically assign a unique vPC system
MAC address. Each vPC domain has a unique MAC address that is used as a unique identifier for the specific
vPC-related operations, although the switches use the vPC system MAC addresses only for link-scope
operations, such as LACP. We recommend that you create each vPC domain within the contiguous network
with a unique domain ID. You can also configure a specific MAC address for the vPC domain, rather than
having the Cisco NX-OS software assign the address.
You must set a unique vPC domain ID to avoid system ID issues with LACP vPCs.
Note
After you create a vPC domain, the Cisco NX-OS software automatically creates a system priority for the
vPC domain. You can also manually configure a specific system priority for the vPC domain.
If you manually configure the system priority, you must ensure that you assign the same priority value on
Note
both vPC peer switches. If the vPC peer switches have different system priority values, the vPC will not
come up.

Peer-Keepalive Link and Messages

The Cisco NX-OS software uses a peer-keepalive link between the vPC peers to transmit periodic, configurable
keepalive messages. You must have Layer 3 connectivity between the peer switches to transmit these messages;
the system cannot bring up the vPC peer link unless a peer-keepalive link is already up and running.
If one of the vPC peer switches fails, the vPC peer switch on the other side of the vPC peer link senses the
failure when it does not receive any peer-keepalive messages. The default interval time for the vPC
peer-keepalive message is 1 second. You can configure the interval between 400 milliseconds and 10 seconds.
You can also configure a timeout value with a range of 3 to 20 seconds; the default timeout value is 5 seconds.
The peer-keepalive status is checked only when the peer-link goes down.
The vPC peer-keepalive can be carried either in the management or default VRF on the Cisco Nexus 5000
Series switch. When you configure the switches to use the management VRF, the source and destination for
the keepalive messages are the mgmt 0 interface IP addresses. When you configure the switches to use the
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
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Information About vPCs
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