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I am studying for ICND1 through CBTNuggets,

I recently watched videos on how to interact between different vlans using separate interfaces, sub-interfaces and Layer 3 Switching.

The first two worked fine for me, but the Layer 3 Switching is not working when i am pinging PC in one VLAN to the PC in other VLAN.

Suppose PC A is connected to Fa0/1 of Switcher and PC B is connected to Fa0/2 of Switcher.

Here is what I did,

I went to Switcher CLI, Went to Global Configuration mode,

created two vlans using commands,

# vlan 10
# vlan 20

Now I moved fa0/0 port to vlan 10 and fa0/1 port to vlan 20

I assigned IP addresses to PCs,

PC A (fa0/1):

10.1.1.100 

Default Gateway: 10.1.1.1 Subnet Mask: 255.255.255.0

PC B (fa0/2):

10.1.2.100

Subnet Mask: 255.255.255.0 Default Gateway: 10.1.2.1

Now i went to the CLi of switcher and did this in Global mode,

# interface vlan 10
# ip address 10.1.1.1 255.255.255.0
# no shutdown
# exit
# interface vlan 20
# ip address 10.1.2.1 255.255.255.0
# no shutdown
# exit

Both vlans 10 and 20 are up and running and all the ports are up too, but I couldn't be able to ping PC B from PC A.

This is exactly what the guy did in the video and he managed to ping.

What did i miss ?

P.S: I also tried to erase arp tables but still couldn't be able to ping.

2
  • Please post the switch config. Jul 7 '14 at 11:42
  • 1
    I am guessing it is a typo, but generally there is no Fa0/0. Did you mean that you moved Fa0/1 to VLAN 10 and Fa0/2 to VLAN 20?
    – YLearn
    Dec 4 '14 at 19:28
7

On the switch, your IP for interface vlan 20 is wrong.

# interface vlan 20
# ip address 10.1.2.1 255.255.255.0
# no shutdown

Then make sure you have ip routing on.

Also the gateway for PC A should be 10.1.1.1 while the gateway for PC B should be 10.1.2.1. The subnet mask should be 255.255.255.0 not the gateway.

Once fixed, make sure you can ping the gateway of each PC from the respective PCs as well.

0

According to you, PC'B' is on fa0/2. This means that PC'B' is on VLAN 1 by default. And PC'A' is in VLAN 20.

That is the mistake i guess

1
  • 1
    This question already has an accepted answer; that was the solution to the problem
    – This
    Dec 5 '14 at 11:16

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