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VTP lab questions

prabhu446
Beginner
Beginner

                   Hello Every one,

I am new to this world and i have some knowledge on VTP and i am trying to implement in the lab. I have 2 switches 3550 and 3750. my questions are:

1. why i can't see vlans in the running config on switch 3750 even after i created 3 vlans?

2. the 3750 is power over ethernet switch and i am trying to connect 3550 and 3750 thru cross over cable trunk link and the ports doesn't show up no light nothing. is it the right way of cabling.

Please help me out.

Thank you.

1 Accepted Solution

Accepted Solutions

The VLAN information in Cisco devices is stored in a separate file from the rest of the device configuration, it is called the vlan.dat file and depending on the IOS version, its information may or may not be included in the running config. If you can see the vlans when you do a "sh vlan" command rest assured they are there.

If you do not have a link between the devices, that is defiantly either a physical problem like a bad cable or one of the ports is shut down. I would definitely pull the crossover out of the mix to try and try using a known good strait-through cable. You must also be sure to use the "mdix auto" command on interface fa1/0/1 of the 3750 to enable the use of the strait-through cable.

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6 Replies 6

Gregory Snipes
Enthusiast
Enthusiast

You cannot see the VLANs on the other switch because your link between them is down and they have no way to propagate the VLAN info.

Why you do not have a link is the question. The crossover should work fine but if you had to make it (as most of us do) and are new to networking it is possible there is a flaw in the cable. The 3750 should support MDIX auto (automatic crossover), so you can try using premade strait-through and let it cross the cable internally.

Hello Gregory thank you for the repsonse:

You cannot see the VLANs on the other switch because your link between them is down and they have no way to propagate the VLAN info. I GET IT but i am trying to do vice versa too i.e creating the vlans on 3750, i can see them under sh vlan output but i can't see them in the sh run output. lets understand that i am dealing with only one switch without VTP to make you understand my point.

Why you do not have a link is the question. The crossover should work fine but if you had to make it (as most of us do) and are new to networking it is possible there is a flaw in the cable. The 3750 should support MDIX auto (automatic crossover), so you can try using premade strait-through and let it cross the cable internally.

Well i have chnaged the cable too and no good. Please suggest me if iam wrong about the cabling i seriously think i am doing the cabling wrong. I have 2 switches Fa1/0/1 on one swt Fa0/1 on other swt configured to trunk and i have connected these ports with a crossover cable. And i have console connection to switches from my work stations that's it no other cables am i missing something DO THESE SWITCHES SHOULD BE CONNECTED TO INTERNET.

Thank you.

The VLAN information in Cisco devices is stored in a separate file from the rest of the device configuration, it is called the vlan.dat file and depending on the IOS version, its information may or may not be included in the running config. If you can see the vlans when you do a "sh vlan" command rest assured they are there.

If you do not have a link between the devices, that is defiantly either a physical problem like a bad cable or one of the ports is shut down. I would definitely pull the crossover out of the mix to try and try using a known good strait-through cable. You must also be sure to use the "mdix auto" command on interface fa1/0/1 of the 3750 to enable the use of the strait-through cable.

the cross over cable isn't working so as you said i tried st cable and its working

Thanks a lot Gregory.

in between i found out why sh run on switch does not show vlans.

When a switch is in VTP server mode it does not show vlan info in the sh run output but shows in sh vlan output.

glen.grant
Advisor
Advisor

   The vlans will only show in the config if you are running transparent mode .  Otherwise they are stored in vlan.dat and you can only see them via the "show vlan " command.

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