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VLAN beginner

ma-si
Level 1
Level 1

For a learning purpose I am creating a VLAN using an old switch: catalyst c2950. 

I used the suggested commands found on this community below

 

Switch(config)#vlan 10
Switch(config-vlan)#name Restricted LAN
Switch(config-vlan)#exit
Switch(config)#int fa1/0 
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 10
Switch(config-if)#end 

 

I assigned the the VLAN 10 to the port 1 to port 8. I connected the port 1 (fa0/1) to a general switch where is connected some PCs a DHCP server and a cisco Router. At port 2 (fa0/2) i connected a PC to test if it was joining the LAN getting for example the IP from the DHCP server.

 

1) It didn't work. 

2) On the port 1 I am receive the error: duplex mismatch discovered. How can I set the "auto negotiating" in between the switches?

 

I am sure I am missing something fundamental .....

 

Thanks

11 Replies 11

Joseph W. Doherty
Hall of Fame
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Unless one of your switches supports auto-MDI (and it's enabled), you need a cross over cable to interconnect to switch ports. Are you using one? (NB: PC to switch, again w/o auto-MDI, would use a straight through cable.)

Jaderson Pessoa
VIP Alumni
VIP Alumni
speed auto
duplex auto
Jaderson Pessoa
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I solved the "auto negotiating " issue using the commands below:

Switch>en
Switch#conf t
Switch(config)#interface f0/1
Marco(config-if)#speed 100
Switch(config-if)#duplex auto

The other switch is a normal NETGEAR GS108 8-Port. In that case do I need a crossover cable to solve the issue?  

 

Thanks

Duplex auto makes sense, but speed 100 should work with speed auto.

Unsure whether your NetGear supports auto-MDI. I recall (?) the 2950 does not.

If the link comes up at all, likely your cable is okay interconnecting the two switches.

balaji.bandi
Hall of Fame
Hall of Fame

here is my commnets :

 

1) It didn't work. 

 

BB - what is not work ? explain more 

 

2) On the port 1 I am receive the error: duplex mismatch discovered. How can I set the "auto negotiating" in between the switches?

 

BB - by default switch set to auto mode, can you post complete log on both the switches.

you may required to set duplex full or half based on the error.

 

try below commands - one at a time both the sides and see if this fix the issue ? 

 

duplex auto

or

duplex full

 

 

Note: I hope these are physical switches right ?  not simulated?

BB

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1) It didn't work. =>  the PC connected to the f0/2 was not part of the LAN (connected to the f0/1)

 

2) error: duplex mismatch discovered =>  When I used "speed auto" it didn't solve the problem. When I used "duplex full" appear a warning message saying the "speed  couldn't be auto". I tried setting the speed at 100 and it seems the error is solved, the error message didn't appear again.

1) It didn't work. =>  the PC connected to the f0/2 was not part of the LAN (connected to the f0/1)

 

So do you 2 VLAN in the network?  original posting may not have that information.

If you still having an issue, post the full config and also what is the PC IP address, what IP address you try to ping?

 

BB

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For a learning purpose I have created a VLAN 10 associated to the first 8 Cisco switch ports. The second VLAN is the default one "VLAN1". All the equipment are real not virtual (PCs included).

 

The PC "VLAN10 test" fa0/2 (in the picture) should get the IP address from the DHCP server as part of the VLAN10 but it doesn't, it is out of the LAN (192.168.1.xx).  

 

 

VLAN 10.png

If your DHCP server is part of the same VLAN, and a pool has been defined for that broadcast domain, PCs connected to that VLAN should be able to obtain a DHCP address. However, for other VLANs you'll need a L3 device which forwards the DHCP requests (along with DHCP defined for them too).

After the Cisco router  there is only a 192.168.1.0 network  LAN. The DHCP server and all PCs are part of this network.

The switch 1 (picture) has the default VLAN 1. The switch 2 has two VLANs: the default VLAN1 and the VLAN 10 with the setting below:

 

 

Switch(config)#vlan 10
Switch(config-vlan)#name Restricted LAN
Switch(config-vlan)#exit
Switch(config)#int fa1/0 
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 10
Switch(config-if)#end

 

 

Do I need to change some setting on the switch 1?

 

 

VLAN 10.png

can you post complete config of Both switch and Rouer to look.

 

Also confirm below actions.

1. in the path you have mentioned netgear switch (is this managed or unmanaged switch)

2. The devices connected to netgear get DHCP IP address ? what IP address they get ?

3. Cisco switch you like to be  just Layer2 ?

 

Once we have above information, we can able to suggest you best

BB

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