Information Technology Reference
In-Depth Information
On an individual trunk link, Cisco generally recommends configuring desirable trunking mode on the
port nearest the network core, and auto trunking mode on the other side of the link. To hard-code
trunking to be enabled, set the trunking mode on both sides to on; you will need to manually set the
VLANs to be forwarded across the trunk link (use the full
set trunk
command) and ensure that the trunk
settings are consistent on either side.
Step 6
ping
Switch B from Switch A to verify that the switches can talk to each other over the link.
Switch-A>
ping 172.16.84.18
172.16.84.18 is alive
Switch-A>
Step 7
Create VLAN 2 in Switch A by entering the
set vlan 2
command on Switch A. Switch B will learn about
VLAN 2 after the DTP domain is established in Step 11.
Switch-A> (enable)
set vlan 2
Vlan 2 configuration successful
Switch-A> (enable)
Step 8
Move the management interface in switches A and B to VLAN 2, which you created previously. Use the
set interface sc0 2
command to do this. The following output shows this being done on Switch A.
Switch-A> (enable)
set int sc0 2
Interface sc0 vlan set.
Switch-A> (enable)
Use the
show interface
command to view the change that you just made. The following output shows
this being done on Switch A.
Switch-A> (enable)
sh int
sl0: flags=51<UP,POINTOPOINT,RUNNING>
slip 0.0.0.0 dest 0.0.0.0
sc0: flags=63<UP,BROADCAST,RUNNING>
vlan 2 inet 172.16.84.17 netmask 255.255.255.0 broadcast 172.16.84.255
Switch-A> (enable)
Step 9
Attempt to
ping
Switch B from Switch A. This should fail because the management ports are now in
VLAN 2, while the link between the switches is in VLAN 1.
Switch-A> (enable)
ping 172.16.84.18
no answer from 172.16.84.18
Switch-A> (enable)
Step 10
Establish the same VTP domain, named Cookbook, for both switches by entering the
set vtp domain
Cookbook
command on both switches.
Switch-A> (enable)
set vtp domain Cookbook
VTP domain Cookbook modified
Switch-A> (enable)
Step 11
Turn on trunking between the switches by configuring port 1/1 on Switch A for desirable mode by
entering the
set trunk 1/1desirable
command on Switch A. Switch B will place its 1/1 port into trunking
mode after the DTP negotiation between the two switches is complete.
Switch-A> (enable)
set trunk 1/1 desirable
Port(s) 1/1 trunk mode set to desirable.
Switch-A> (enable)
You should see the following message as ISL becomes active:
1999 Aug 10 15:33:10 %DTP-5-TRUNKPORTON:Port 1/1 has become isl trunk
