Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Cat 3550 3560 vlans


I beleive these cat switches do layer 3 routing. therefore is it possible to run separate Vlans without the need of a router?

If so has anyone got any documentation on configuring this?

Many Thanks

J Mac


Re: Cat 3550 3560 vlans

Yes.. You can just create the interface VLAN's but do not place an IP address under them. YOu then assign your ports to their respected VLANs using the switchport access vlan xxx. First you need to set the ports to switchport mode (under the interface use the SWITCHPORT command). This sets the port an access port...Good Luck...

Re: Cat 3550 3560 vlans

Background Theory

In a switched network, VLANs separate devices into different collision domains and Layer 3 (L3) subnets. Devices within a VLAN can communicate with each other without the need for routing. Devices in separate VLANs require a routing device to communicate with one another.

L2-only switches require an L3 routing device. The device is either external to the switch or in another module on the same chassis. A new breed of switches incorporate routing capability within the switch. An example is the 3550. The switch receives a packet, determines that the packet belongs to another VLAN, and sends the packet to the appropriate port on the other VLAN.

A typical network design segments the network based on the group or function to which the device belongs. For example, the engineering VLAN only has devices that relate to the engineering department, and the finance VLAN only has devices that relate to finance. If you enable routing, the devices in each VLAN can talk to one another without the need for all the devices to be in the same broadcast domain. Such a VLAN design also has an additional benefit. The design allows the administrator to restrict communication between VLANs with use of access lists. In the example in this document, you can use access lists to restrict the engineering VLAN from access to devices on the finance VLAN.

This link have a configurations example and nice drawing for better understanding of the theory: