Asante IntraCore 6524, Руководство пользователя

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VLAN Management
Page 4-23
Inter-Switch Links
An inter-switch link (ISL) is a port that connects VLANS that reside on two
different switches. An ISL is the means to share VLAN information between
switches on a network.
For example, consider the two-switch network in Figure 4-6, which connects
the Ethernet segments, E-1 through E-9. Assume port 1 on each switch is set up
as default; it passes untagged frames. Also assume port 2 on each switch is
configured to accept only tagged frames, which limits traffic to VLAN 1. In that
case, VID 1 frames from E-1 will never reach E-5.
An ISL is necessary to connect VLAN 1 across the switches. The ISL is
established by configuring port 1 as a member of VLAN 1 on both switch 1 and
switch 2. Both instances of port 1 must transmit tagged frames, and a typical
ISL is also configured to drop untagged frames. In that case, VLAN 1 is
connected across the switches.
Figure 4-6 An Inter-Switch Link
The configuration of the ISL ports and the other ports on each switch
determines how tagged frames are transmitted across the switches. For example,
2 3 4 5
1
6 5 4 3 2
1
E-1
E-2
E-3
E-4
E-5
E-6
E-7
E-8
E-9
VID 4
VID 3
VID 4
VID 2
VID 3
VID 2
Switch 1 Switch 2