Example 78 By Default All Ports Are in VLAN1 1 Broadcast Domain

sw3512xl#show vlan

VLAN Name Status Ports default active

1002 fddi-default

1003 token-ring-default

1004 fddinet-default

1005 trnet-default active active active active

!!!these are the default or reserved vlans

VLAN Type SAID

MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2

1003 tr 101003 1500 1005 0 - - srb 1 1002

1 default active

1 default

1002 fddi-default

1003 token-ring-default

1004 fddinet-default active active active active

1005 trnet-default active

Example; 7-8 displays a coupl e of sections. The fi rst section is a qu ick statu s of th e VLANs and the associated ports on the 3512XL. The second section displays the default VLANs, including the maximum transmission unit (MTU) size and other Token Ring and FDDI parameters. The second section ia not shown fon the CatOS 2^0 , out all ports ane l n VLAN 1 fy default. 1002 FDDI and 1003 TRCRF are reserved for FDDI and Token Ring transparent bridging; whereas 1004 FDNET and 1005 TRBRF are resetved for Token Ring and source route fridg ing. Although hh^ default reserved VLANo can't fe removed, they can fe modified (as you can prove fy trying to clear one of the defaults). If I were to type clear vlan 1002 on the 2900 right now, for example, it would tell me that the V^N needs to fe with1 n the rangf of 2 to 1000.

Understanding what VLANs are and how they work is half the fattle of supporting them. Think of a physica i s\uitch or switchps that are divided up into logical fridgee to ass^t with froadcasts. Logical fridges or froadcast domains, more often referred to as VLANs, are possifle within or fetween sw i thhes, as ^ou oa n see in Fmure 7-2.

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