Administrator Guide

To ensure that existing network applications see no dierence when a primary interface in a redundant pair transitions to the backup
interface, be sure to apply identical congurations of other trac parameters to each interface.
If you remove an interface in a redundant link (remove the line card of a physical interface or delete a port channel with the no
interface port-channel command), the redundant pair conguration is also removed.
Important Points about Conguring Redundant Pairs
• You may not congure any interface to be a backup for more than one interface, no interface can have more than one backup, and a
backup interface may not have a backup interface.
• The active or backup interface can be a LAG, but it cannot be a member port of a LAG.
• The active and standby do not have to be of the same type (1G, 10G, and so on).
• You may not enable any Layer 2 protocol on any interface of a redundant pair or to ports connected to them.
As shown in the above illustration, interface 3/41 is a backup interface for 3/42, and 3/42 is in the Down state. If 3/41 fails, 3/42 transitions
to the Up state, which makes the backup link active. A message similar to the following message appears whenever you congure a backup
port.
02:28:04: %RPM0-P:CP %IFMGR-5-L2BKUP_WARN: Do not run any Layer2 protocols on Gi 3/41 and Te
3/42
02:28:04: %RPM0-P:CP %IFMGR-5-OSTATE_DN: Changed interface state to down: Gi 3/42
02:28:04: %RPM0-P:CP %IFMGR-5-STATE_ACT_STBY: Changed interface state to standby: Gi 3/42
Example of Conguring Redundant Layer 2 Pairs
DellEMC(conf-if-range-Gi-3/41-42)#switchport backup interface GigabitEthernet 3/42
DellEMC(conf-if-range-Gi-3/41-42)#show config
!
interface GigabitEthernet 3/41
no ip address
switchport
switchport backup interface GigabitEthernet 3/42
no shutdown
!
interface GigabitEthernet 3/42
no ip address
switchport
no shutdown
DellEMC(conf-if-range-Gi-3/41-42)#
DellEMC(conf-if-range-Gi-3/41-42)#do show ip int brief | find 3/41
GigabitEthernet 3/41 unassigned YES Manual up up
GigabitEthernet 3/42 unassigned NO Manual up down
[output omitted]
DellEMC(conf-if-range-Gi-3/41-42)#interface gig 3/41
DellEMC(conf-if-Gi-3/41)#shutdown
00:24:53: %RPM0-P:CP %IFMGR-5-ASTATE_DN: Changed interface Admin state to down: Gi 3/41
DellEMC(conf-if-Gi-3/41)#00:24:55: %RPM0-P:CP %IFMGR-5-OSTATE_DN: Changed interface state to
down: Gi 3/41
00:24:55: %RPM0-P:CP %IFMGR-5-INACTIVE: Changed Vlan interface state to inactive: Vl 1
00:24:55: %RPM0-P:CP %IFMGR-5-OSTATE_UP: Changed interface state to up: Gi 3/42
00:24:55: %RPM0-P:CP %IFMGR-5-ACTIVE: Changed Vlan interface state to active: Vl 1
00:24:55: %RPM0-P:CP %IFMGR-5-STATE_STBY_ACT: Changed interface state from standby to active:
Gi 3/42
DellEMC(conf-if-Gi-3/41)#do show ip int brief | find 3/41
GigabitEthernet 3/41 unassigned NO Manual administratively down down
GigabitEthernet 3/42 unassigned YES Manual up up
[output omitted]
Example of Conguring Redundant Pairs on a Port-Channel
DellEMC#show interfaces port-channel brief
Codes: L - LACP Port-channel
LAG Mode Status Uptime Ports
Layer 2
483