Cisco Cisco Nexus 5010 Switch Guía Para Resolver Problemas
L2MP based forwarding across vPC peer−link in
Carmel ASIC based switches(Nexus 5548/5596)
Carmel ASIC based switches(Nexus 5548/5596)
Document ID: 115900
Contributed by Prashanth Krishnappa, Cisco TAC Engineer.
Jul 03, 2014
Jul 03, 2014
Contents
Introduction
Prerequisites
Requirements
Components Used
Conventions
Loop avoidance
Related Information
Prerequisites
Requirements
Components Used
Conventions
Loop avoidance
Related Information
Introduction
In vPC topologies user traffic will be seen on peer−link only for orphan port traffic or flooded traffic
(unknown unicast, broadcast, multicast). For this flood traffic, there is a requirement that switches make sure
flood traffic received on one leg of the vPC is not sent back on the other vPC leg so that packets are not sent
back towards source or duplicated to other vPCs.
(unknown unicast, broadcast, multicast). For this flood traffic, there is a requirement that switches make sure
flood traffic received on one leg of the vPC is not sent back on the other vPC leg so that packets are not sent
back towards source or duplicated to other vPCs.
In Carmel based switches (Nexus 55xx), vPC loop avoidance implementation is different compared to Gatos
(Nexus 5010/5020) based implementation which uses a separate internal MCT VLAN for flooded traffic
across peer−link.
(Nexus 5010/5020) based implementation which uses a separate internal MCT VLAN for flooded traffic
across peer−link.
Because Carmel based switches support L2MP or fabricpath, engineering decided to use L2MP based
forwarding across the peer−link. With this model, vPC primary switch will have a switch−id of 2748(0xabc)
while the vPC secondary will have a switch−id of 2749(0xabd). The Emulated switch−id of 2750(0xabe) will
be used as source switch−id for frames which ingress a vPC but sent across the peer−link. All ports on the
vPC primary will be members of FTAG 256 while that on the vPC secondary will be members of FTAG 257.
In vPC primary switch, only orphan ports will be members of FTAG 257 while in the vPC secondary switch,
orphan ports will be members of FTAG 256.
forwarding across the peer−link. With this model, vPC primary switch will have a switch−id of 2748(0xabc)
while the vPC secondary will have a switch−id of 2749(0xabd). The Emulated switch−id of 2750(0xabe) will
be used as source switch−id for frames which ingress a vPC but sent across the peer−link. All ports on the
vPC primary will be members of FTAG 256 while that on the vPC secondary will be members of FTAG 257.
In vPC primary switch, only orphan ports will be members of FTAG 257 while in the vPC secondary switch,
orphan ports will be members of FTAG 256.
Prerequisites
Requirements
There are no specific requirements for this document.
Components Used
This document is not restricted to specific software and hardware versions.
Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.