Campus Network Question

[cisconoobie]

In a Campus Network design where you have Core switch, Distribution switch and Access switch layers and SVI's acting as your gateways for different VLANs.

Since it is advised that Core Switches should be the root bridges, does that mean that the Core Switches should be the default gateways for your Vlans?

I thought that it was the job of the distribution layer for being the default gateways.

Anyone clarify?

[royalblues]

hi friend,

It generally depends on your LAN design.

If you follow Cisco's 3 tier architecture, you should restrict your VLAN boundaries on the distribution switch and should be running a L3 link between the core and the distribution. This means the SVI's are created on the distribution switch which will act as gateways for your VLANs.

This helps in restricting the broadcasts from reaching the core.

If your LAN is actually a collapsed core, you end up configuring the SVIs on the distribution switch which also acts as your core.

HTH, rate if it does

Narayan

[cisconoobie]

So in a 3 tier design, the root bridge is still on the Core? even though the default gateways are configured on the Distribution layer switches?

[royalblues]

No my friend,

If you are running a L3 link between the core and the distribution, spanning tree doesn't come into picture at all.

Check the link for more details

http://www.cisco.com/application/pdf/en/us/guest/netsol/ns432/c649/ccmigration_09186a00805fccbf.pdf

HTH, rate if it does

Narayan

[mattmar]

The core switches should NOT be doing layer 2. Therefore there is no bridging on the Core switches and no need for root bridges. A core switch should be routing packets and be layer 3 only. This eliminates fault domains.