MLAG Configuration
This chapter contains a complete example of Multi-Chassis Link Aggregation (MLAG) configuration.
MLAG expands the concept of link aggregation so that it provides node-level redundancy by allowing two or more nodes to share a common LAG endpoint. It emulates multiple nodes to represent as a single logical node to the remote node running Link aggregation. As a result, even if one of the nodes is down there exists a path to reach the destination through the other nodes.
Note: MLAG is only compatible with VPWS.
Note: MLAG is supported only in Active-Standby mode.
Note: All MLAG nodes must have the same MAC table size - as specified by each node's switching ASIC forwarding profile limit.
Topology
In the below example TOR1 and TOR2 forms a MLAG domain.
As shown in Figure 13-28, TOR1 and TOR2 forms a domain and thus provides the redundancy.
Even if TOR1 or TOR2 is down, there exist a redundant path to forward the traffic.
Figure 13-28: MLAG Topology
Configuration
Switch 1
SW1#configure terminal | Enter the config terminal. |
(config)#hostname SW1 | Assign the hostname for the router. |
SW1(config)#bridge 1 protocol rstp vlan-bridge | Create bridge. |
SW1(config)#vlan database | Enter the VLAN database. |
SW1(config-vlan)#vlan 2-1002 bridge 1 state enable | Create the VLANs. |
SW1(config-vlan)#exit | Exit the VLAN database. |
SW1(config)#int po1 | Enter the interface mode. |
SW1(config-if)#switchport | Configure the interface as Layer 2. |
SW1(config-if)#bridge-group 1 | Assign the bridge to the interface. |
SW1(config-if)#switchport mode trunk | Configure the interface as trunk mode. |
SW1(config-if)#switchport trunk allowed vlan all | Configure the interface to allow all VLAN ids. |
SW1(config-if)#exit | Exit the interface mode. |
SW1(config)#int xe15 | Enter the interface mode. |
SW1(config-if)#channel-group 1 mode active | Add the interface as member of LAG interface. |
SW1(config-if)#int xe31 | Enter the interface mode. |
SW1(config-if)#channel-group 1 mode active | Add the interface as member of LAG interface. |
SW1(config-if)#commit | Commit the configure on the node. |
SW1(config-if)#exit | Exit the interface mode. |
TOR-1
TOR1#configure terminal | Enter the config terminal. |
TOR1(config)#hostname TOR1 | Assign the hostname for the router. |
TOR1(config)#bridge 1 protocol rstp vlan-bridge | Create bridge. |
TOR1(config)#vlan database | Enter the VLAN database. |
TOR1(config-vlan)#vlan 2-1002 bridge 1 state enable | Create the VLANs. |
TOR1(config-vlan)#exit | Exit the VLAN database. |
TOR1(config)#int mlag1 | Create the MLAG interface. |
TOR1(config-if)#switchport | Configure the interface as Layer 2. |
TOR1(config-if)#bridge-group 1 | Assign the bridge to the interface. |
TOR1(config-if)#switchport mode trunk | Configure the interface as trunk mode. |
TOR1(config-if)#switchport trunk allowed vlan all | Configure the interface to allow all VLAN ids. |
TOR1(config-if)#exit | Exit the interface mode. |
TOR1(config)#int mlag2 | Create the MLAG interface. |
TOR1(config-if)#switchport | Configure the interface as Layer 2. |
TOR1(config-if)#bridge-group 1 | Assign the bridge to the interface. |
TOR1(config-if)#switchport mode trunk | Configure the interface as trunk mode. |
TOR1(config-if)#switchport trunk allowed vlan all | Configure the interface to allow all VLAN ids. |
TOR1(config-if)#exit | Exit the interface mode. |
TOR1(config)#int po1 | Create the port channel interface. |
TOR1(config-if)#switchport | Configure the interface as Layer 2. |
TOR1(config-if)#mlag 1 | Bind MLAG to the port channel. |
TOR1(config-if)#exit | Exit the interface mode. |
TOR1(config)#int po2 | Create the port channel interface |
TOR1(config-if)#switchport | Configure the interface as Layer 2. |
TOR1(config-if)#mlag 2 | Bind MLAG to the port channel. |
TOR1(config-if)#exit | Exit the interface mode. |
TOR1(config)#interface xe7 | Enter the interface mode |
TOR1(config-if)#switchport | Configure the interface as Layer 2. |
TOR1(config-if)#exit | Exit the interface mode. |
TOR1(config)#int xe15 | Enter the interface mode. |
TOR1(config-if)#channel-group 1 mode active | Add the interface as member of LAG interface. |
TOR1(config-if)#exit | Exit the interface mode. |
TOR1(config)#int xe11 | Enter the interface mode. |
TOR1(config-if)#channel-group 2 mode active | Add the interface as member of LAG interface. |
TOR1(config-if)#exit | Exit the interface mode. |
TOR1(config)#mcec domain configuration | Enter the MCEC mode. |
TOR1(config-mcec-domain)#domain-system-number 1 | Assign the domain system number for MLAG interface. |
TOR1(config-mcec-domain)#domain-address 1111.2222.3333 | Assign the domain address. |
TOR1(config-mcec-domain)#domain-hello-timeout short | Assign the domain hello timeout. |
TOR1(config-mcec-domain)#intra-domain-link xe7 | Assign the interface as IDL. |
TOR1(config-mcec-domain)#exit | Exit the MCEC domain. |
TOR1(config-mcec-domain)#commit | Commit the configure on the node. |
TOR1(config)#exit | Exit the config terminal. |
TOR-2
TOR2#configure terminal | Enter the config terminal. |
TOR2(config)#hostname TOR2 | Assign the hostname for the router. |
TOR2(config)#bridge 1 protocol rstp vlan-bridge | Create bridge. |
TOR2(config)#vlan database | Enter the VLAN database. |
TOR2(config-vlan)#vlan 2-1002 bridge 1 state enable | Create the VLANs. |
TOR2(config-vlan)#exit | Exit the VLAN database. |
TOR2(config)#int mlag1 | Create the MLAG interface. |
TOR2(config-if)#switchport | Configure the interface as Layer 2 |
TOR2(config-if)#bridge-group 1 | Assign the bridge to the interface. |
TOR2(config-if)#switchport mode trunk | Configure the interface as trunk mode. |
TOR2(config-if)#switchport trunk allowed vlan all | Configure the interface to allow all VLAN ids. |
TOR2(config-if)#exit | Exit the interface mode. |
TOR2(config)#int mlag2 | Create the MLAG interface. |
TOR2(config-if)#switchport | Configure the interface as Layer 2. |
TOR2(config-if)#bridge-group 1 | Assign the bridge to the interface. |
TOR2(config-if)#switchport mode trunk | Configure the interface as trunk mode. |
TOR2(config-if)#switchport trunk allowed vlan all | Configure the interface to allow all VLAN ids. |
TOR2(config-if)#exit | Exit the interface mode. |
TOR2(config)#int po1 | Create the port channel interface |
TOR2(config-if)#switchport | Configure the interface as Layer 2 |
TOR2(config-if)#mlag 1 | Bind MLAG to the port channel. |
TOR2(config-if)#exit | Exit the interface mode. |
TOR2(config)#int po2 | Create the port channel interface. |
TOR2(config-if)#switchport | Configure the interface as Layer 2. |
TOR2(config-if)#mlag 2 | Bind MLAG to the port channel. |
TOR2(config-if)#exit | Exit the interface mode. |
TOR1(config)#interface xe7 | Enter the interface mode |
TOR1(config-if)#switchport | Configure the interface as Layer 2. |
TOR1(config-if)#exit | Exit the interface mode. |
TOR2(config)#int xe32 | Enter the interface mode. |
TOR2(config-if)#channel-group 1 mode active | Add the interface as member of LAG interface. |
TOR2(config-if)#exit | Exit the interface mode. |
TOR2(config)#int xe5 | Enter the interface mode |
TOR2(config-if)#channel-group 2 mode active | Add the interface as member of LAG interface. |
TOR2(config-if)#exit | Exit the interface mode. |
TOR2(config)#mcec domain configuration | Enter the MCEC mode. |
TOR2(config-mcec-domain)#domain-system-number 2 | Assign the domain system number for MLAG interface. |
TOR2(config-mcec-domain)#domain-address 1111.2222.3333 | Assign the domain address. |
TOR2(config-mcec-domain)#domain-hello-timeout short | Assign the domain hello timeout. |
TOR2(config-mcec-domain)#intra-domain-link xe7 | Assign the interface as IDL. |
TOR2(config-mcec-domain)#exit | Exit the MCEC domain. |
TOR2(config-mcec-domain)#commit | Commit the configure on the node. |
TOR2(config)#exit | Exit the config terminal. |
Switch 2
SW2#configure terminal | Enter the config terminal. |
SW2(config)#hostname SW2 | Assign the hostname for the router. |
SW2(config)#bridge 1 protocol rstp vlan-bridge | Create bridge. |
SW2(config)#vlan database | Enter the VLAN database |
SW2(config-vlan)#vlan 2-1002 bridge 1 state enable | Create the VLANs. |
SW2(config-vlan)#exit | Exit the VLAN database |
SW2(config)#int po2 | Enter the interface mode |
SW2(config-if)#switchport | Configure the interface as Layer 2 |
SW2(config-if)#bridge-group 1 | Assign the bridge to the interface. |
SW2(config-if)#switchport mode trunk | Configure the interface as trunk mode. |
SW2(config-if)#switchport trunk allowed vlan all | Configure the interface to allow all VLAN ids. |
SW2(config-if)#exit | Exit the interface mode. |
SW2(config)#int xe11 | Enter the interface mode. |
SW2(config-if)#channel-group 2 mode active | Add the interface as member of LAG interface. |
SW2(config-if)#int xe5 | Enter the interface mode. |
SW2(config-if)#channel-group 2 mode active | Add the interface as member of LAG interface. |
SW2(config-if)#commit | Commit the configure on the node. |
SW2(config-if)#exit | Exit the interface mode. |
Validation
Switch 1
SW1#show etherchannel summary
Aggregator po1 100001
Aggregator Type: Layer2
Admin Key: 0001 - Oper Key 0001
Link: xe15 (5015) sync: 1
Link: xe31 (5031) sync: 0
SW1#
SW1#show etherchannel detail
Aggregator po1 100001
Aggregator Type: Layer2
Mac address: 34:17:eb:e4:af:10
Admin Key: 0001 - Oper Key 0001
Actor LAG ID- 0x8000,34-17-eb-4b-af-00,0x0001
Receive link count: 1 - Transmit link count: 1
Individual: 0 - Ready: 1
Partner LAG ID- 0x8000,11-11-22-22-33-33,0x4001
Link: xe15 (5015) sync: 1
Link: xe31 (5031) sync: 0
Collector max delay: 5
SW1#
TOR 1
TOR1#show etherchannel summary
Aggregator po1 100001
Aggregator Type: Layer2
Admin Key: 16385 - Oper Key 16385
Link: xe15 (5015) sync: 1 (Mlag-active-link)
--------------------------------------
Aggregator po2 100002
Aggregator Type: Layer2
Admin Key: 16386 - Oper Key 16386
Link: xe11 (5011) sync: 1 (Mlag-active-link)
TOR1#
TOR1#show mlag domain summary
------------------------------------
Domain Configuration
------------------------------------
Domain System Number : 1
Domain Address : 1111.2222.3333
Domain Priority : 32768
Intra Domain Interface : xe7
Domain Adjacency : UP
Domain Sync via : Intra-domain-interface
------------------------------------
MLAG Configuration
------------------------------------
MLAG-1
Mapped Aggregator : po1
Physical properties Digest : 54 a9 3a 2a 2b 50 65 bb 3c bc 3d bd c2 43 d6 22
Total Bandwidth : 10g
Mlag Sync : IN_SYNC
Mode : Active-Standby
Current Mlag state : Active
Switchover-mode : Revertive
MLAG-2
Mapped Aggregator : po2
Physical properties Digest : 54 a9 3a 2a 2b 50 65 bb 3c bc 3d bd c2 43 d6 22
Total Bandwidth : 10g
Mlag Sync : IN_SYNC
Mode : Active-Standby
Current Mlag state : Active
Switchover-mode : Revertive
TOR1#
TOR1#show etherchannel detail
Aggregator po1 100001
Aggregator Type: Layer2
Mac address: 3c:2c:99:1a:da:89
Admin Key: 16385 - Oper Key 16385
Actor LAG ID- 0x8000,11-11-22-22-33-33,0x4001
Receive link count: 1 - Transmit link count: 1
Individual: 0 - Ready: 1
Partner LAG ID- 0x8000,34-17-eb-4b-af-00,0x0001
Link: xe15 (5015) sync: 1 (Mlag-active-link)
Collector max delay: 5
---------------------------------------------------
Aggregator po2 100002
Aggregator Type: Layer2
Mac address: 3c:2c:99:1a:da:85
Admin Key: 16386 - Oper Key 16386
Actor LAG ID- 0x8000,11-11-22-22-33-33,0x4002
Receive link count: 1 - Transmit link count: 1
Individual: 0 - Ready: 1
Partner LAG ID- 0x8000,3c-2c-99-c0-9f-79,0x0002
Link: xe11 (5011) sync: 1 (Mlag-active-link)
Collector max delay: 5
TOR1#
TOR1#show mcec statistics
Unknown MCCPDU received on the system : 0
------------------------------------
IDP : xe7
------------------------------------
Valid RX Hello PDUs : 4054
Valid TX Hello PDUs : 4191
Valid RX Info PDUs : 66
Valid TX Info PDUs : 16
Valid RX Mac Sync PDUs : 53
Valid TX Mac Sync PDUs : 61
MLAG 1
Valid RX Info PDUs : 9
Valid TX Info PDUs : 8
MLAG 2
Valid RX Info PDUs : 12
Valid TX Info PDUs : 8
TOR1#
TOR 2
TOR2#show etherchannel summary
Aggregator po1 100001
Aggregator Type: Layer2
Admin Key: 32769 - Oper Key 16385
Link: xe32 (5032) sync: 0 (Mlag-standby-link)
--------------------------------------
Aggregator po2 100002
Aggregator Type: Layer2
Admin Key: 32770 - Oper Key 16386
Link: xe5 (5005) sync: 0 (Mlag-standby-link)
TOR2#
TOR2#show etherchannel detail
Aggregator po1 100001
Aggregator Type: Layer2
Mac address: 80:a2:35:c4:e9:73
Admin Key: 32769 - Oper Key 16385
Actor LAG ID- 0x8000,11-11-22-22-33-33,0x4001
Receive link count: 0 - Transmit link count: 0
Individual: 0 - Ready: 1
Partner LAG ID- 0x8000,34-17-eb-4b-af-00,0x0001
Link: xe32 (5032) sync: 0 (Mlag-standby-link)
Collector max delay: 5
---------------------------------------------------
Aggregator po2 100002
Aggregator Type: Layer2
Mac address: 80:a2:35:c4:e9:58
Admin Key: 32770 - Oper Key 16386
Actor LAG ID- 0x8000,11-11-22-22-33-33,0x4002
Receive link count: 0 - Transmit link count: 0
Individual: 0 - Ready: 1
Partner LAG ID- 0x8000,3c-2c-99-c0-9f-79,0x0002
Link: xe5 (5005) sync: 0 (Mlag-standby-link)
Collector max delay: 5
TOR2#
TOR2#
TOR2#show mlag domain summary
------------------------------------
Domain Configuration
------------------------------------
Domain System Number : 2
Domain Address : 1111.2222.3333
Domain Priority : 32768
Intra Domain Interface : xe7
Domain Adjacency : UP
Domain Sync via : Intra-domain-interface
------------------------------------
MLAG Configuration
------------------------------------
MLAG-1
Mapped Aggregator : po1
Physical properties Digest : 54 a9 3a 2a 2b 50 65 bb 3c bc 3d bd c2 43 d6 22
Total Bandwidth : 10g
Mlag Sync : IN_SYNC
Mode : Active-Standby
Current Mlag state : Standby
Switchover-mode : Revertive
MLAG-2
Mapped Aggregator : po2
Physical properties Digest : 54 a9 3a 2a 2b 50 65 bb 3c bc 3d bd c2 43 d6 22
Total Bandwidth : 10g
Mlag Sync : IN_SYNC
Mode : Active-Standby
Current Mlag state : Standby
Switchover-mode : Revertive
TOR2#
TOR2#show mcec statistics
Unknown MCCPDU received on the system : 0
------------------------------------
IDP : xe7
------------------------------------
Valid RX Hello PDUs : 4177
Valid TX Hello PDUs : 4159
Valid RX Info PDUs : 16
Valid TX Info PDUs : 66
Valid RX Mac Sync PDUs : 74
Valid TX Mac Sync PDUs : 30
MLAG 1
Valid RX Info PDUs : 8
Valid TX Info PDUs : 27
MLAG 2
Valid RX Info PDUs : 8
Valid TX Info PDUs : 39
TOR2#
Switch 2
SW2#show etherchannel summary
Aggregator po2 100002
Aggregator Type: Layer2
Admin Key: 0002 - Oper Key 0002
Link: xe5 (5005) sync: 0
Link: xe11 (5011) sync: 1
SW2#show etherchannel detail
Aggregator po2 100002
Aggregator Type: Layer2
Mac address: 3c:2c:99:26:e6:7f
Admin Key: 0002 - Oper Key 0002
Actor LAG ID- 0x8000,3c-2c-99-c0-9f-79,0x0002
Receive link count: 1 - Transmit link count: 1
Individual: 0 - Ready: 1
Partner LAG ID- 0x8000,11-11-22-22-33-33,0x4002
Link: xe5 (5005) sync: 0
Link: xe11 (5011) sync: 1
Collector max delay: 5
SW2#
Last modified date: 10/12/2023