In many of the Internetwork Expert labs you are asked to create VLAN assignments based on the information in the network diagram. Here is my two step process for accomplishing that task.
1) Issue ‘show ip int br | e ass’ command and look for SVIs and routed ports.
Rack22SW1#sh ip int br | e ass
Interface IP-Address OK? Method Status Protocol
Vlan7 155.22.7.7 YES manual down down
Vlan67 155.22.67.7 YES manual down down
Vlan79 155.22.79.7 YES manual down down
FastEthernet0/13 155.22.37.7 YES manual up up
Loopback0 150.22.7.7 YES manual up up
For SVIs, if they are down then add the appropriate VLANs:
Rack22SW1(config)#vlan 7,67,79
Rack22SW1(config-vlan)#exit
Wait a bit while STP comes up and then verify that the SVIs come up (you should be using this time to start on step 2):
00:37:29: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan7, changed state to up
00:37:29: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan67, changed stateto up
00:37:29: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan79, changed stateto up
Rack22SW1(config-if)#do sh ip int br | e ass
Interface IP-Address OK? Method Status Protocol
Vlan7 155.22.7.7 YES manual up up
Vlan67 155.22.67.7 YES manual up up
Vlan79 155.22.79.7 YES manual up up
FastEthernet0/13 155.22.37.7 YES manual up up
Loopback0 150.22.7.7 YES manual up up
For the routed ports, find out what port the other side of the link terminates on (‘show cdp neighbor’ or check physical wiring diagram). If it is a router or another routed switchport, then just verify the IP address and make sure that the port is up. IF it is a layer 2 switchport, then you will need to add the VLAN to that switchport. For instance, if sw1 fa0/13 is a routed switchport in VLAN 123:
Rack22SW1(config)#do sh run int fa0/13
Building configuration…
Current configuration : 88 bytes
!
interface FastEthernet0/13
no switchport
ip address 155.22.123.7 255.255.255.0
end
Rack22SW1(config)#do sh cdp neigh fa0/13
Capability Codes: R – Router, T – Trans Bridge, B – Source Route Bridge
S – Switch, H – Host, I – IGMP, r – Repeater, P – Phone
Device ID Local Intrfce Holdtme Capability Platform Port ID
Rack22SW2 Fas 0/13 161 S I WS-C3560-2Fas0/13
Rack22SW2(config)#int fa0/13
Rack22SW2(config-if)#switch access vlan 123
% Access VLAN does not exist. Creating vlan 123
2) Using the physical wiring diagram and/or CDP, find the ports that connect to the routers:
Rack22SW1(config)#do sh cdp neigh | e SW
Capability Codes: R – Router, T – Trans Bridge, B – Source Route Bridge
S – Switch, H – Host, I – IGMP, r – Repeater, P – Phone
Device ID Local Intrfce Holdtme Capability Platform Port ID
Rack22R1 Fas 0/1 169 R S I 2610XM Fas0/0
Rack22R3 Fas 0/3 170 R S I 2611XM Fas0/0
Rack22R5 Fas 0/5 169 R S I 2611XM Fas0/0
Using the network topology find out which VLAN each router port is in and assign the appropriate VLAN to the interface [NOTE: I like to look at the configuration of each switchport before configuring them just in case there is something funky from the initial configuration]. In this case, r1 fa0/0 is in VLAN 146 and r5 fa0/0 is in VLAN 58. sw1 fa0/3 is a routed IP interface so we can leave it alone.]
Rack22SW1(config)#int fa0/1
Rack22SW1(config-if)#sw ac vla 146
% Access VLAN does not exist. Creating vlan 146
Rack22SW1(config-if)#do sh run int fa0/3
Building configuration…
Current configuration : 86 bytes
!
interface FastEthernet0/3
no switchport
ip address 155.22.37.7 255.255.255.0
end
Rack22SW1(config-if)#int fa0/5
Rack22SW1(config-if)#sw ac vla 58
% Access VLAN does not exist. Creating vlan 58
Once you are done you should verify your layer 2 configuration by pinging across each VLAN (assuming that all trunking has been built). If your pings fail, check your layer 2 transit path as well as the other endpoint’s interface (I’ve wasted much labtime troubleshooting my L2 network only to discover that the router port is shutdown). You can also verify your access VLAN configuration with the following command (assuming all links are FastEthernet):
Rack22SW1#sh vlan br | i Fa
1 default active Fa0/2, Fa0/4, Fa0/6, Fa0/7
Fa0/8, Fa0/9, Fa0/10, Fa0/11
Fa0/12, Fa0/22, Fa0/23, Fa0/24
58 VLAN0058 active Fa0/5
146 VLAN0146 active Fa0/1
Anyhoo…I hope that this helps. I’ll return to “full blogging mode” tonight.