In
this lab you will familiarize yourself with the following commands;
Command
|
Description
|
|---|---|
switchport
mode trunk
|
This
command when executed in interface configuration mode on a switch
port will configure the switchport as a trunk port which carries
all VLAN traffic.
|
switchport
trunk encapsulation isl
|
This
command is executed in interface configuration mode to specify
that the trunk will use the Cisco Inter-Switch Link (ISL)
encapsulation protocol.
|
switchport
trunk encapsulation dot1q
|
This
command is executed in interface configuration mode to specify
that the trunk will use the IEEE 802.1q standard encapsulation
protocol.
|
show
interface trunk
|
This
command is executed in privileged mode to show which interfaces
are currently trunking and which trunking protocol is used.
|
show
interface interfacename#/# switchport
|
This
command when executed in privileged mode will show information
relating to the specified interface such as the interface
operational mode (trunk or access), native vlan, trunking VLAN’s
permitted on the trunk link and more.
|
Lab Prerequisites
- Establish a console session with devices SW1, SW2, R1 and R2 than configure the devices respected hostname(s).
- Configure R1′s FastEthernet0/0 interface with the IP Address 10.1.1.1/24 and R2′s FastEthernet0/1 interface with the IP address of 10.1.1.2/24
- Create VLAN 10 as a layer 2 VLAN on SW1 and SW2. (Layer 2 VLAN’s do not have Layer 3 VLAN interfaces representing the VLAN; ie, no interface Vlan10.)
- Configure SW1′s FastEthernet0/1 and SW2′s FastEthernet0/2 interfaces as static access interfaces for VLAN 10.
Lab Objectives
- Shutdown interfaces FastEthernet0/11 and FastEthernet0/12 on both SW1 and SW2 and configure an IEEE 802.1q trunk on interface FastEthernet0/10 of both SW1 and SW2.
- Verify your trunk link configuration by using the show interface interfacename#/# trunk command.
- Verify that R1 has IP reachability to R2 by using ping command on R1.
- Change SW1′s FastEthernet0/2 interface to be placed into VLAN 5 and verify your verify IP reachability between R1 and R2 again.
Read
Me
The
Lab instruction for this lab is demonstrated using a Cisco Catalyst
3560 Series Switch, not the NM-16ESW.. Also note that the NM-16ESW
does not support ISL trunk encapsulation which will be demonstrated
in the lab instruction.
Lab Instruction
Step
1. – Shutdown interfaces FastEthernet0/11 and FastEthernet0/12 on
both SW1 and SW2 and configure an IEEE 802.1q trunk on interface
FastEthernet0/10 of both SW1 and SW2.
To
configure an interface as a static trunk you’ll first need to
configure the encapsulation type first as an interface whose trunk
encapsulation is “Auto” can not be configured to “trunk”
mode.
SW1 con0 is now available Press RETURN to get started. SW1>enable SW1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW1(config-if)#interface range Fa0/11 - 12 SW1(config-if-range)#shutdown SW1(config-if-range)#interface fa0/10 SW1(config-if)#switchport trunk encapsulation dot1q SW1(config-if)#switchport mode trunk SW1(config-if)#no shut SW1(config-if)#end SW1#
And
now the same configuration on SW2;
SW2 con0 is now available Press RETURN to get started. SW2>enable SW2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW2(config-if)#interface range Fa0/11 - 02 SW2(config-if-range)#shutdown SW2(config-if-range)#interface fa0/10 SW2(config-if)#switchport trunk encapsulation dot1q SW2(config-if)#switchport mode trunk SW2(config-if)#no shut SW2(config-if)#end SW2#
Step
2 . – Verify your trunk link configuration by using the show
interface FastEthernet0/10 trunk command as
shown below on both SW1 and SW2;
SW1#show interface FastEthernet0/10 trunk Port Mode Encapsulation Status Native vlan Fa0/10 on 802.1q trunking 1 Port Vlans allowed on trunk Fa0/10 1-4094 Port Vlans allowed and active in management domain Fa0/10 1,10 Port Vlans in spanning tree forwarding state and not pruned Fa0/10 1 SW1# SW2#show interface FastEthernet0/10 trunk Port Mode Encapsulation Status Native vlan Fa0/10 on 802.1q trunking 1 Port Vlans allowed on trunk Fa0/10 1-4094 Port Vlans allowed and active in management domain Fa0/10 1,10 Port Vlans in spanning tree forwarding state and not pruned Fa0/10 1 SW2#
Step
3. – Verify that R1 has IP reachability to R2 by using ping command
on R1.
Now
that you have a trunk link between SW1 and SW2, traffic generated on
SW1 in VLAN 10 should be able to propagate to VLAN 10 on SW2. To test
this, ping R2′s FastEthernet 0/1 interface (IP Address 10.1.1.2)
From R1 as shown below;
R1#ping 10.1.1.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds: .!!!! Success rate is 80 percent (4/5), round-trip min/avg/max = 4/29/60 ms R1#
When
you ping R2′s FastEthernet0/1 interface IP address from R1, the
router knows that the destination IP address is on the same local
subnet therefore it ARP’s for the MAC address of host 10.1.1.2,
This ARP request is received on SW1 and forwarded to SW2 and onto R2
which responds “Hey I’m 10.1.1.2, my MAC address is
ABCD.EF12.3456″. Now that R1 knows the MAC address for 10.1.1.2 it
then fowards the ICMP packet towards SW1 with the correct destination
MAC address. Initially SW1 will not know the location of that MAC
address because the machine is not local to that switch so therefore
it will forward the frame out interfaces within that VLAN except the
interface that the frame was received on. When the frame is received
by SW2 it then is switched out the correct port as the MAC exists
already in its MAC address table. When R2 responds to the ICMP packet
it will then go the opposite way towards SW1. After SW1 receives a
response from R2 destined to R1 seeing a NEW source MAC address that
SW1 has not learned it will then install the MAC address into the CAM
Table (Mac Address Table) for future use.
Step 4. – Change SW1′s FastEthernet0/2 interface to be placed into VLAN 5 and verify your verify IP reachability between R1 and R2 again.
You
can also test this further by placing SW2′s interface that is
connected to R2 in a different vlan and attempt to ping R2 from R1
and no doubly it will fail as shown below;
SW2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW2(config)#interface FastEthernet0/2 SW2(config-if)#switchport access vlan 5 % Access VLAN does not exist. Creating vlan 5 SW2(config-if)#end SW2# R1#ping 10.1.1.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds: ..... Success rate is 0 percent (0/5) R1#
As
demonstrated in this lab you can use trunk links to pass traffic in
multiple VLAN’s between multiple switches using a single link.
Due
to the NM-16ESW and Cisco 2950 not supporting the ISL trunk
encapsulation, a configuration example is given below. Note that the
only configuration difference between Dot1q and ISL is the switchport
trunk encapsulation isl
| dot1q command option.
c3560-Switch1>enable c3560-Switch1#configure terminal c3560-Switch1(config)#interface fa0/10 c3560-Switch1(config-if)#switchport trunk encap isl c3560-Switch1(config-if)#switchport mode trunk c3560-Switch1(config-if)#end c3560-Switch1#sh int fa0/10 trunk Port Mode Encapsulation Status Native vlan Fa0/10 on isl trunking 1 Port Vlans allowed on trunk Fa0/10 none Port Vlans allowed and active in management domain Fa0/10 none Port Vlans in spanning tree forwarding state and not pruned Fa0/10 none c3560-Switch1#
