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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 14 Co n figuring VLANs
Unders tanding VLAN s
For a Catalyst 295 0 LRE Switch, th e maxim um supported num ber of VLA Ns is 250, t he maximum
number of STP inst ances is 64, an d trunkin g is supported. The Catal yst 2950 LRE also supports 4094
VLAN IDs. The 2950 LRE software image is based on the EI software and supports the same number of
VLANs, VLAN IDs, and STP instances as the EI software image.
Figure 14-1 shows an exam ple of V L ANs segmented into l ogica lly defined n etwor ks.
Figure 14-1 VLANs as Logically Defined Networks
VLANs are often associated with IP subnetworks. For example, all the end stations in a particular IP
subnet belo ng to t he sa me V LAN . In terfa ce V L AN m embe rshi p on the swi tch is a ssigne d ma nual ly on
an interfac e-b y-interfa ce basis. When you assign switch interfaces to VLANs b y using this method, it is
known as interface-based, or static, VLAN membership.

Supported VLANs

Catalyst 29 50 swi tch es that run the sta ndar d sof tware ima ge (SI) supp ort 6 4 V LAN s; swit che s that ru n
the enha nc ed sof twar e imag e (EI ) supp ort 2 50 VLANs . Refe r t o the rel ease notes for th e li st of s witch es
that support each image. VLANs are identified with a number from 1 to 4094 when the EI is installed
and 1 to 1005 wh en the SI is instal led. V LAN IDs 1002 th rough 1005 ar e reserved for Token Ring and
FDDI VLANs. VTP only learns normal-range VLANs, with VLAN IDs 1 to 1005; VLAN IDs greater
than 1005 are extend ed-ra ng e VLAN s and are not st ored i n the VLAN da tab ase. T he swit ch must be in
VTP tran spa ren t m od e w hen y ou cr ea te VLA N I D s from 1 006 to 409 4.
The switc h supports pe r-VLAN span ning tree (PVS T) with a maxi mum of 64 spanning- tree inst ances.
One spa nn i ng- tr ee in s tan ce i s al lowed p er V L AN . S e e t he N orma l-Ra nge VL AN Con figuration
Guidelines section on page 14-5 fo r more info rmation a bout th e number o f spanni ng-tre e instance s and
the nu mber of VL ANs. T he swi tch su ppor ts IEE E 802 .1 Q trun king fo r sen di ng V LAN tra ffic over
Ether net port s.
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