Nortel Networks WEB OS 212777 - Manual (Page 45)

Web OS 10.0 Application Guide
Chapter 2: VLANs n 45
212777-A, February 2002
VLANs and the IP Interfaces
Carefully consider how you create VLANs within the switch, so that communication with the
switch Management Processor (MP) remains possible.
You can access the switch for remote configuration, trap messages, and other management
functions only from stations on VLANs that include an IP interface to the switch (see “IP Inter-
face Menu” section in the Web OS Command Reference). Likewise, you can cut off access to
management functions to any VLAN by excluding IP interfaces from the VLAN’s member-
ship.
For example, if all IP interfaces are left on VLAN 1 (the default), and all ports are configured
for VLANs other than VLAN 1, then switch management features are effectively cut off. If an
IP interface is added to one of the other VLANs, the stations in that VLAN will all have access
to switch management features.
VLAN Topologies and Design Issues
By default, the Web OS software has a single VLAN configured on every port. This configura-
tion groups all ports into the same broadcast domain. The VLAN has an 802.1Q VLAN PVID
of 1. VLAN tagging is turned off, because by default only a single VLAN is configured per
port.
Since VLANs are most commonly used to create individual broadcast domains and/or separate
IP subnets, host systems should be present on more than one VLAN simultaneously. Alteon
Web switches and VLAN-tagging server adapters support multiple VLANS on a per-port or
per-interface basis, allowing very flexible configurations.
You can configure multiple VLANs on a single VLAN-tagging server adapter, with each
VLAN being configured through a logical interface and logical IP address on the host system.
Each VLAN configured on the server adapter must also be configured on the switch port to
which it is connected. If multiple VLANs are configured on the port, tagging must be turned
on.
Using this flexible multiple VLAN system, you can logically connect users and segments to a
host with a single VLAN-tagging adapter that supports many logical segments or subnets.