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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 5 Configuring Ethernet VLAN Trunks
Example VLAN Trunk Configurations
mode status device port
----- ---------- --------- ----------- ------------------------- ----------
3/1 connected auto channel WS-C5500 069003103(Sw 1/1
3/2 connected auto channel WS-C5500 069003103(Sw 1/2
----- ---------- --------- ----------- ------------------------- ----------
Switch_B> (enable)
Step 4
Configure one of the ports in the EtherChannel bundle to negotiate an ISL trunk by entering the
set trunk
command.
The configuration is applied to all of the ports in the bundle. This example assumes that the neighboring
ports on Switch B are configured to use
isl
or
negotiate
encapsulation and are in
auto
trunk mode. The
system logging messages provide information about the formation of the ISL trunk.
Switch_A> (enable)
set trunk 1/1 desirable isl
Port(s) 1/1-2 trunk mode set to desirable.
Port(s) 1/1-2 trunk type set to isl.
Switch_A> (enable) %DTP-5-TRUNKPORTON:Port 1/1 has become isl trunk
%DTP-5-TRUNKPORTON:Port 1/2 has become isl trunk
%PAGP-5-PORTFROMSTP:Port 1/1 left bridge port 1/1-2
%PAGP-5-PORTFROMSTP:Port 1/2 left bridge port 1/1-2
%PAGP-5-PORTTOSTP:Port 1/1 joined bridge port 1/1-2
%PAGP-5-PORTTOSTP:Port 1/2 joined bridge port 1/1-2
Switch_B> (enable) %DTP-5-TRUNKPORTON:Port 3/1 has become isl trunk
%DTP-5-TRUNKPORTON:Port 3/2 has become isl trunk
%PAGP-5-PORTFROMSTP:Port 3/1 left bridge port 3/1-2
%PAGP-5-PORTFROMSTP:Port 3/2 left bridge port 3/1-2
%PAGP-5-PORTTOSTP:Port 3/1 joined bridge port 3/1-2
%PAGP-5-PORTTOSTP:Port 3/2 joined bridge port 3/1-2
Step 5
After the ISL trunk link is negotiated, verify the configuration by entering the
show trunk
command.
Switch_A> (enable)
show trunk
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
1/1 desirable isl trunking 1
1/2 desirable isl trunking 1
Port Vlans allowed on trunk
-------- ---------------------------------------------------------------------
1/1 1-1005, 1025-4094
1/2 1-1005, 1025-4094
Port Vlans allowed and active in management domain
-------- ---------------------------------------------------------------------
1/1 1-5,10,20,50,152,200,300,400,500,521-524,570,850,917,999
1/2 1-5,10,20,50,152,200,300,400,500,521-524,570,850,917,999
Port Vlans in spanning tree forwarding state and not pruned
-------- ---------------------------------------------------------------------
1/1 1-5,10,20,50,152,200,300,400,500,521-524,570,850,917,999
1/2 1-5,10,20,50,152,200,300,400,500,521-524,570,850,917,999
Switch_A> (enable)
Switch_B> (enable)
show trunk
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
3/1 auto isl trunking 1
3/2 auto isl trunking 1
Port Vlans allowed on trunk
-------- ---------------------------------------------------------------------
3/1 1-1005, 1025-4094