Hi, We want to set up a resilent internet connection between backbone and outing going network by using 4 GB ethernet. It's demanded that the four GB ethernet connection are grouped into two GB channels ( two work horse + two backup), HSRP + STP are requirement to enable system reliablity. It's also expected to use 8 IP addresses for network i nterconnection between backbone and outgoing network. We plan to provide such service by using GB interfaces on two catalyst 6509. But, to my understanding if the two GB channels are configured with 2*4 interconnection IP addresses, STP is not required between our switches and customer's switches. And, the two GB channel could participate two HSRP groups, and acts as primary and standby sequently. GB Catalyst6509-A =================== Catalyst6509-B <- outgoing （layer2+layer3) || || || GB Channel || GB Channel || 2GB || Catalyst 2948G =================== Catalyst2948G <-Core ( maybe only layer2 ) network with two class C address To the topology above, I think the 8 interconnection IP addresses are not required. But, if the two GB channels are configured into one VLAN, the number of of host in one collision domain will be 2*256, this will surely derive to broadcast storm. I don't know how to set up IP routing in Layer 3 of 6509-A and 6509-B either. How could it done? Each word will be highly appreciated. Regards Joe Shen ---- Msg sent via Spymac Mail - http://www.spymac.com