Static Virtual LANs (VLANs)

Static VLAN Operation

Static VLAN Operation

A group of networked ports assigned to a VLAN form a broadcast domain that is separate from other VLANs that may be configured on the switch. On a given switch, packets are bridged between source and destination ports that belong to the same VLAN. Thus, all ports passing traffic for a particular subnet address should be configured to the same VLAN. Cross-domain broadcast traffic in the switch is eliminated and bandwidth is saved by not allowing packets to flood out all ports.

Table 2-1. Comparative Operation of Port-Based and Protocol-Based VLANs

Port-Based VLANs

Protocol-Based VLANs

 

 

IP

Usually configured with at least one unique IP

Addressing

address. You can create a port-based VLAN with-

 

out an IP address. However, this limits the switch

 

features available to ports on that VLAN. (Refer to

 

“How IP Addressing Affects Switch Operation” in

 

the chapter “Configuring IP Addressing” in the

 

Management and Configuration Guide for the

 

switch.)

 

You can also use multiple IP addresses to create

 

multiple subnets within the same VLAN. (For more

 

on this topic, refer to the chapter on “Configuring

 

IP Addressing” in the Management and

 

Configuration Guide for the switch.)

You can configure IP addresses on all protocol VLANs. However, IP addressing is used only on IPv4 and IPv6 protocol VLANs.

The maximum number of IP addresses supported on a switch is 256. Each IP address that you configure on a VLAN interface must be unique in the switch.

For more information, refer to the chapter on “Configuring IP Addressing” in the Management and Configuration Guide.

Untagged

A port can be a member of one untagged, port-

VLAN

based VLAN. All other port-based VLAN

Membership

assignments for that port must be tagged.

A port can be an untagged member of one protocol VLAN of a specific protocol type (such as IPX or IPv6). If the same protocol type is configured in multiple protocol VLANs, then a port can be an untagged member of only one of those protocol VLANs. For example, if you have two protocol VLANs, 100 and 200, and both include IPX, then a port can be an untagged member of either VLAN 100 or VLAN 200, but not both VLANs.

A port’s untagged VLAN memberships can include up to four different protocol types. This means that a port can be an untagged member of one of the following:

•Four single-protocol VLANs

•Two protocol VLANs where one VLAN includes a single protocol and the other includes up to three protocols

•One protocol VLAN where the VLAN includes four protocols

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