Distributed Trunking and VRRP in switches

[jchen522]

When connecting two 5406R switches to a uplink third party switch,

Should the uplinks to the third switch be configured as Distributed Trunking? 

What about on the third switch?  Should its down links be configured as LACP? 

The two switches are configured for VRRP as well, will it still work in a failover situation?

[Vince-Whirlwind]

LACP and VRRP are two completely different and independent things - LACP is about feeding frames to members of groups of links, whereas VRRP is about providing a router address to send packets to.

If you are using both together, then frames on a VLAN will be sent to both 5406s, but only one of the 5406s will do the routing of the packets inside those frames. So if the frame appears on the 5406 that is the "Backup" router for that VLAN's subnet, the frame will be forwarded at Layer2 to the "Master" where the routing will be performed.

If one 5406 goes down, then all its links are down, so no frames are forwarded to it. 

If the VRRP backup 5406 goes down, routing continues on the Master. If the Master 5406 goes down, the Backup starts doing the routing.