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In a redundant pair, any combination of physical and port-channel interfaces is supported as the two interfaces in a redundant
pair. For example, you can configure a static (without LACP) or dynamic (with LACP) port-channel interface as either the
primary or backup link in a redundant pair with a physical interface.
To ensure that existing network applications see no difference when a primary interface in a redundant pair transitions to the
backup interface, be sure to apply identical configurations of other traffic 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 configuration is also removed.
Important Points about Configuring Redundant Pairs
● You may not configure 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 may not be a member 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 previous 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 configure a backup port.
02:28:04: %RPM0-P:CP %IFMGR-5-L2BKUP_WARN: Do not run any Layer2 protocols onTe 3/41 and
Te 3/42
02:28:04: %RPM0-P:CP %IFMGR-5-OSTATE_DN: Changed interface state to down: Te 3/42
02:28:04: %RPM0-P:CP %IFMGR-5-STATE_ACT_STBY: Changed interface state to standby: Te 3/42
Example of Configuring Redundant Layer 2 Pairs
Dell(conf-if-range-te-3/41-42)#switchport backup interface TenGigabitEthernet 3/42
Dell(conf-if-range-te-3/41-42)#show config
!
interface TenGigabitEthernet 3/41
no ip address
switchport
switchport backup interface TenGigabitEthernet 3/42
no shutdown
!
interface TenGigabitEthernet 3/42
no ip address
switchport
no shutdown
Dell(conf-if-range-te-3/41-42)#
Dell(conf-if-range-te-3/41-42)#do show ip int brief | find 3/41
TenGigabitEthernet 3/41 unassigned YES Manual up up
TenGigabitEthernet 3/42 unassigned NO Manual up down
[output omitted]
Dell(conf-if-range-te-3/41-42)#interface tengig 3/41
Dell(conf-if-te-3/41)#shutdown
00:24:53: %STKUNIT0-M:CP %IFMGR-5-ASTATE_DN: Changed interface Admin state to down: Te
3/41
Dell(conf-if-te-3/41)#00:24:55: %STKUNIT0-M:CP %IFMGR-5-OSTATE_DN: Changed interface
state to
down: Te 3/41
00:24:55: %STKUNIT0-M:CP %IFMGR-5-INACTIVE: Changed Vlan interface state to inactive: Vl
1
00:24:55: %STKUNIT0-M:CP %IFMGR-5-OSTATE_UP: Changed interface state to up: Te 3/42
00:24:55: %STKUNIT0-M:CP %IFMGR-5-ACTIVE: Changed Vlan interface state to active: Vl 1
00:24:55: %STKUNIT0-M:CP %IFMGR-5-STATE_STBY_ACT: Changed interface state from standby to
active: Te 3/42
Dell(conf-if-te-3/41)#do show ip int brief | find 3/41
TenGigabitEthernet 3/41 unassigned NO Manual administratively down down
TenGigabitEthernet 3/42 unassigned YES Manual up up
[output omitted]
Layer 2
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