Collapsed backbone

[loobitize]

I have a medium sized network and I am thinking about building a collapsed backbone network as shown in:

http://www.cisco.com/en/US/customer/netsol/ns340/ns394/ns147/ns17/networking_solutions_white_paper09186a00800a3e16.shtml

I have a 6509 w/ dual Sup 1a's and a 4500 w/ dual supIV's that I will use at the core. Each access layer switch supports multiple VLAN's and I would like the entire network to be part of one VTP domain.

I have a number of questions regarding this model.

1) Should the link between the 4500 and the 6500 be a trunk or a dedicated VLAN to route traffic over? What are the advanatages or disadvantages?

2) How do I configure the connetions from the access layer switches to the core switches? If I use trunks and uplink fast on the access switches, and layer 3 between the core switches, how will the access switches know if the link between the two core switches goes down?

3) How can I keep the switches in one VTP domain if I don't have a trunk between the two core switches?

[r-simpson]

Before you can create a VLAN, the switch must be in VTP server mode or VTP transparent mode. If the switch is a VTP server, you must define a VTP domain name before you can add any VLANs. This has to be defined regardless of the number of switches in the network (one or many), or whether or not you will be using VTP to propagate VLANs to other switches in the network. For details on VTP, refer to Understanding and Configuring VLAN Trunk Protocol (VTP).

http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094c52.shtml

[mohamed-khadr]

1) yes, u need to config a trunk bet 65xx 45xx with .1q encap.

2) You have to config VLANs for server farm and edge switches(users PCs).U have to config HSRP on both core switches.

HTH

mohAmed khAdr

[vinodmorsa]

Hi,

We did something similar to this. The answers would be:

1) Trunk with dot1q if you have a large number of vlans. Go for a separate vlan interface if the vlans are less and you can afford a separate port for each vlan. This can be helpful if you want to do a vlan based hsrp at the core.

2)Use backbone fast. This will let the access switches know if any of the core switches is down.

3)You will need to have a trunk port.

Thanks,

Vinod