Help needed with VLAN

SV

I am facing difficulty configuring VLAN when using NetSim 5.31
I am using two 2900 series switches: SW1 and SW2. I configured both in the same VTP domain where SW1 is the VTP server and SW2 a client. The f0/0 port in both the switches is configured as the trunking ports. I created 2 VLANs and attached the f0/1 ports of both the switches to VLAN 1 and f0/2 ports of both the switches to VLAN 2.

When I issue the “show vlan” command while in SW2, I can see the name of VLAN 1 & 2 that was added to the VLAN database in SW1.

The issue is that I am not able to ping the host connected to f0/1 in SW1 from f0/1 in SW2.

Has any one tried this using NetSim 5.31?

johnnynodough

*Correction again*

I didnt read your post right the first time, nor the second

Did you configure encapsulation on the trunks?

Webmaster

SV wrote:

I created 2 VLANs and attached the f0/1 ports of both the switches to VLAN 1

As they are in the same VLAN, did you assign them IP addresses that are in the same subnet?

johnnynodough

I just went through a setup on my NetSim 5.31 and was able to get it up correctly, I think you are just missing your encapsulation (dot1q)

SV

johnnynodough wrote:

I just went through a setup on my NetSim 5.31 and was able to get it up correctly, I think you are just missing your encapsulation (dot1q)

All the hosts in the VLAN 1 belong to the same network. I am sure about the IP addresses.

Since you are able to get it right using your simulator, most probably the issue might be with the encapsulation. I will definitely check that.

Thank you all for the valuable suggestions.

Mr.Noe

Did you issue the switchport mode access and switchport access vlan. As I recall all ports on a switch are in trunking mode you may have to put them in access mode. Encapsulation should be fine, the default is dot1q for both switches.

johnnynodough

The default on a switchport is dynamic auto, so if a peer port is set for dynamic desirable or trunk, the port will go into trunk mode. If both are dynamic auto, they wont activley attempt to negotiate a trunk, and therefore will run in access mode.

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/12_18a/command/s1.htm#1022472

As far as encapsulation with dot1q automatically occuring when a trunk is setup, for sure in the Boson Netsim, you have to specify it or else with wont apply. In real life I am not sure, I will verify that tonight when I get home on my lab.

SV

johnnynodough wrote:

As far as encapsulation with dot1q automatically occuring when a trunk is setup, for sure in the Boson Netsim, you have to specify it or else with wont apply. In real life I am not sure, I will verify that tonight when I get home on my lab.

Yah, as per books I believe we do not have to configure encapsulations…. but with the sim... I am not sure.

One thing I am sure is that both the switches can ping each other.

Will check with the dot1q encapsulation tonight. If it still does not work, will send the whole settings and commands used in detail. Thanks a lot for the help. Really appreciate it.

johnnynodough

I wasnt able to verify the need for the swithport trunk encapsulation dot1q command on my lab at home, I have 2924XL EN's, which support dot1q and ISL, so I definetely need to specify encap type on mine.

SV

Guys ... I am not thorough .... BUT I found the solution.

I entered the command “no switchport access vlan all” on the trunk ports in both the switches and everything worked fine. This means by default “switchport access vlan all” was configured on the switches !!!

Just to make sure that it was the answer, I created a new LAN setting from scratch using two 2900 series switches. Even this time just by entering the above command computers in the same VLAN across multiple switches were able to communicate with each other. I didn’t have to change the encapsulation types.

Do we have to enter the same command in real switched too?

johnnynodough

That has to be a bug in the Netsim, if you issue a trunkport command, that would make those ports be in a trunk, which would override the swithport mode access command. So if you had to negate the swithport mode access command, that would have to be becuase either you configured it, or because you didnt configure it as a trunk as my 2nd post above states. Two ports in default mode will not make a trunk. I tested this on my 2900's and the same thing happends, if I issue a swithport mode trunk command, thats it, I have a trunk, I only need to do it on one switch since the defualt state is dynamic auto, and the peer port will go into trunk as well.

Thats another bug in Netsim, boy the list gets bigger everyday

SV

I am sure that I configured trunk ports using "switchport mode trunk" command. As mentioned earlier, just to confirm the answer, I configured multiple LAN settings from scratch.

Yah... I believe its a bug.