Force10 S4810 VLT – Quick Configuration sample


I have already given a non-technical synopsis on VLT in one of my previous posts here

As mentioned, VLT Is a Dual Active Control Plane implementation, of a Multi System LAG. Cisco vPC is a similar technology.

VLT is beneficial in environments where the downstream devices like servers or access/distribution switches need to build port channels/LAGs across two separate upstream switches. in this context, VLT resembles what stacking offers. The other benefit is that due to distinct control planes, it is possible to perform maintenance one switch at a time without taking the entire fabric down. This is unlike stacking, where the entire fabric must be taken down for upgrades etc.

Here, i will provide a quick configuration sample on getting VLT operational between two VLT peer (S4810) switches.


VLT – Backup Link FTOS(conf)# interface TenGigabitEthernet 0/xx You must configure the backup link before you can configure the VLT trunk interconnect. Here, i am connecting an in-band L3 link back-to-back between the peers.
description To VLT peer – backup link
ip address x.x.x.x/24
no shutdown
 Port-Channel (VLTi)
FTOS(conf)# interface Port-channel 100 Enter the same port-channel number configured with the
peer-link port-channel command in the Enable VLT
and create a VLT Domain steps
 description VLTi To peer-switch
  channel-member fortyGigE 0/48
  channel-member fortyGigE 0/56
  vlt-peer-lag port-channel 100
  no shutdown
VLTi member ports FTOS(conf)# interface fortyGigE 0/48
FTOS(conf-if-fe-0/48)#  description To VLT peer – VLTi
FTOS(conf-if-fe-0/48)#  no ip address
FTOS(conf-if-fe-0/48)#  no shutdown
FTOS(conf-if-fe-0/56)# exi
FTOS(conf)# interface fortyGigE 0/56
FTOS(conf-if-fe-0/56)#  description To VLT peer – VLTi
FTOS(conf-if-fe-0/56)#  no ip address
FTOS(conf-if-fe-0/56)#  no shutdown
FTOS(conf-if-fe-0/56)# exi
VLT Domain FTOS(conf)# vlt domain 1
 peer-link port-channel 100 IP address of the interface on the remote VLT peer to be used as the endpoint of the VLT backup link for sending out-of-band hello messages.
 back-up destination x.x.x.x
 primary-priority 1
 unit-id 0
VLT Downstream clients FTOS(conf)# interface port-channel 1 Port-Channels to Servers
no ip address
Servers switchport
spanning-tree rstp edge-port
  channel-member tenGigE 0/1
no shutdown Associate the port channel to the corresponding port channel in the VLT peer for the VLT connection to an attached device.
vlt-peer-lag port-channel 1
FTOS(conf)# interface TenGigabitEthernet 0/1
description To downstream Server xyz
no ip address
port-channel-protocol LACP
port-channel 2 mode active Channel # 2 is the downstream PoCH to the server, on each peer.
no shutdown


This ofcourse, will need to be repeated on the VLT peer Switch as well, and the values that need changing will have to changed.


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