Encapsulation problem

I have three switches - I'll call them A, B, and C. I configured port 9 on switch A for trunking, and connected it to port 9 on switch B. I tried to configure port 9 there, but I keep getting a message ""native VLAN mismatch on fa 0/9." I had initially configured vlan 1 with an IP address, but whether I have it configured or not, I keep getting the same error. And the commands I input on switch A to configure a trunk - switch mode trunk; switch trunk encapsulation dot1q - don't work on switch B. When I input "switch mode....", my only options are "access" or "multilink"; no "trunk."

Switch A is a 2900 XL and switches B and C are plain old 2900s. Any suggestions?

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Comments

Netstudent

try the

switchport trunk native vlan 1 on both ends of the trunk to ensure they both have the default native vlan.

Komkommer

Perhaps switch A simply doesn't support trunking.

Netstudent

I have a 2924XL that trunks.

Also try the "show interface fast 0/9 switchport" to see what the native VLAN is set to.

mikej412

Check the Cisco site to see if those other switches support dot1q, or if they even can be upgraded to support it.

Try ISL encapsulation on the 2924

Tricon7

Mikej412, you're a lifesaver. That seemed to work. Since I don't have 2950 switches, I have to do more work. I changed switch A to isl, then I got a message on switch B "port 0/9 unblocked." :P

*Sigh* - however, more problems now; I should be able to create a sub-interface on the router and give it an encapsulation type, like dot1q or isl. But after I've created the sub-interface, there are no encapsulation options. I even typed a "?" at the prompt, and "encapsulation" didn't appear. I'm reading right out of Cisco's book right now, and I know that sequence and procedure is right, so I'm puzzled as to why it won't accept it. And if I try and assign an IP address to a sub-interface, I get the message:

Configuring IP routing on a LAN subinterface is only allowed if that subinterface is already configured as part of an IEEE 802.10 or ISL vLAN.

Suggestions?

networker050184

Not all routers support inter VLAN routing (trunkung) just like all switches do not support all types of trunking. You should check to ensure you have all the up to date equipment and IOS.

tech-airman

Tricon7 wrote:

Mikej412, you're a lifesaver. That seemed to work. Since I don't have 2950 switches, I have to do more work. I changed switch A to isl, then I got a message on switch B "port 0/9 unblocked." :P

*Sigh* - however, more problems now; I should be able to create a sub-interface on the router and give it an encapsulation type, like dot1q or isl. But after I've created the sub-interface, there are no encapsulation options. I even typed a "?" at the prompt, and "encapsulation" didn't appear. I'm reading right out of Cisco's book right now, and I know that sequence and procedure is right, so I'm puzzled as to why it won't accept it. And if I try and assign an IP address to a sub-interface, I get the message:

Configuring IP routing on a LAN subinterface is only allowed if that subinterface is already configured as part of an IEEE 802.10 or ISL vLAN.

Suggestions?

Tricon7,

Do you have the appropriate IOS version that supports VLAN trunking?

Tricon7

tech-airman wrote:

Tricon7 wrote:

Mikej412, you're a lifesaver. That seemed to work. Since I don't have 2950 switches, I have to do more work. I changed switch A to isl, then I got a message on switch B "port 0/9 unblocked." :P

*Sigh* - however, more problems now; I should be able to create a sub-interface on the router and give it an encapsulation type, like dot1q or isl. But after I've created the sub-interface, there are no encapsulation options. I even typed a "?" at the prompt, and "encapsulation" didn't appear. I'm reading right out of Cisco's book right now, and I know that sequence and procedure is right, so I'm puzzled as to why it won't accept it. And if I try and assign an IP address to a sub-interface, I get the message:

Configuring IP routing on a LAN subinterface is only allowed if that subinterface is already configured as part of an IEEE 802.10 or ISL vLAN.

Suggestions?

Tricon7,

Do you have the appropriate IOS version that supports VLAN trunking?

That I do not know; what's the minimum IOS version I would need to support encapsulation, do you know? I have a 2600 Cisco router.

networker050184

12.1 for either ISL or dot1q I believe on the 2600 routers.

dtlokee

It needs to be an IP enhanced feature set, c2600-is at a minimum.

Tricon7

Perhaps someone could take a look at this Cisco link and let me know which item I need to download to my switch, which won't encapsulate?

http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp

mikej412

You either need a 100Mb port, or to trunk on a 2610 10Mb port I think it was 12.2T IP Enhanced or higher (12.3).

Hum.... your new avatar makes you look smarter!

ryhay

Hello!
im having the same problem with several 2620 routers using IOS 12.2(5d) and 12.2(5a)

anchorage(config-subif)#encap?
% Unrecognized command

apparantly my IOS' dont include the ip enhanced functionality, my routers are past EoL and i dont have a cisco service agreement with which to get IOS revisions.

do you have to actually pay Cisco or is there another way that im missing to obtain IOS revisions for unsupported products?

thanks for any help..!

networker050184

Read the forums this question has been asked many times and answered many times as well.