I was recently asked to assist our training environment with the deployment of mid market Dell data center utilizing OS 10 and Virtual Link Trunking. VLT is Dell’s implementation of multi-chassis etherchannel, similar to Cisco’s Virtual Port Channel. OS10 is an open networking platform, runs on Debian Linux and boots of the ONIE (Open Network Install Environment) boot loader.

For this environment / lab here is our bill of materials:
2 x Dell S4112F-ON
2 x Dell R640 1 RU servers
1 x Dell sc3000v2 SAN
1 x Palo Alto Networks PA-220

Dell Data Centre Design

Dell Data Centre Design

Dell vLT allows multiple switches to appear as one logical unit. VLT has layer 3 routing features and as such out of box can replace FHRR protocols such as VRRP. In this design there is a pair of S4112F-ON switches connected at 100gb/s. The left side is PVST+ root bridge for all VLANs and it is also the primary vLT peer. One thing to note in regard to the Dell vLT peer-routing feature. Both L3 SVI IP addresses will perform IP routing for a subnet, if the primary switch in a VLT peer goes down then the secondary will transparently respond to IP routing request. You can not ping the primary gateway IP when this fail over scenario is in affect. Note that vLT port-channels require a mirror of configuration on both switch members. This is regardless of access or trunk mode port-channels. There is an example below.

Here is the OS10 (10.4.2.2.265) configuration to achieve the above vLT design:
Core-1

vlt-domain 1
backup destination 192.168.x.2
discovery-interface ethernet 1/1/14-1/1/15
peer-routing
primary-priority 1
vlt-mac 00:11:22:33:44:56

interface port-channel3
description PA-Internet-Uplink
no shutdown
switchport access vlan 550
vlt-port-channel 3

interface ethernet1/1/7
description Link-1-to-PA
no shutdown
channel-group 3

Core-2

vlt-domain 1
backup destination 192.168.x.1
discovery-interface ethernet 1/1/14-1/1/15
peer-routing
vlt-mac 00:11:22:33:44:56

interface port-channel3
description PA-Internet-Uplink
no shutdown
switchport access vlan 550
vlt-port-channel 3

interface ethernet1/1/7
description Link-1-to-PA
no shutdown
channel-group 3