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Community Member

Catalyst 4506 Problems

Hello everyone -


I'm having a very strange issue with a new Catalyst 4506 I'm standing up right now, and haven't seen this before...  I'm just about finished configuring the device, and am putting the final configurations in and have run into some trouble.

The switch is very basic, a SUPIV, an 18 port GBIC blade, and a 48 port gigabit ethernet blade.  I'm trying to configure my GBIC ports set to trunking, with dot1q encapsulation, and the first 2 ports it works without an issue.  On the rest of the ports on the blade, the command simply isn't there.  Basically, i'm trying to do an - interface range gi2/1 - 2/8, switchport trunk encapsulation dot1q, and then switchport mode trunk.  After inputting the switchport trunk encapsulation command, I get the message "command failed on interface gigabit ethernet 2/3", aborting.

Not sure what's causing this, if anyone has seen this issue before, please shed a little light .


Thanks!

Jonathan Kloza

CACI Technologies

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Blue

Re: Catalyst 4506 Problems

Jkloza wrote:

Yes, the command works without any issues on the 48 port blade.  That said, I could just get away with using switchport mode trunk without setting an

encapsulation, the command doesn't fail.  From the research that i've done it seems like there's a limit on how many ISL trunks you can configure on a 4500 series switch, but that really doesn't make any sence to me.

The ports are all unconfigured, there's a configuration on the switch, but this is the first time i've tried to setup the different interface configurations.

Jonathan

It is a limitation on that particular module. The first 2 ports are non-blocking and support either ISL or 802.1q trunking. The remaining 16 ports which are oversubscribed only support 802.1q trunking and so the "switchport trunk encapsulation ..." command is not available for those ports.

Jon

9 REPLIES

Re: Catalyst 4506 Problems

Hi Jon

This is strange .... Are you facing an issue only with the 18 port Gig module, or also on the 48 port module ? just to troubleshoot, were you able to configure say ISL trunking  or access vlan on these ports ? Is the log file showing any errors ? All these modules are new, and just have basic configs already right ?

Raj

Community Member

Re: Catalyst 4506 Problems

Yes, the command works without any issues on the 48 port blade.  That said, I could just get away with using switchport mode trunk without setting an

encapsulation, the command doesn't fail.  From the research that i've done it seems like there's a limit on how many ISL trunks you can configure on a 4500 series switch, but that really doesn't make any sence to me.

The ports are all unconfigured, there's a configuration on the switch, but this is the first time i've tried to setup the different interface configurations.

Hall of Fame Super Blue

Re: Catalyst 4506 Problems

Jkloza wrote:

Yes, the command works without any issues on the 48 port blade.  That said, I could just get away with using switchport mode trunk without setting an

encapsulation, the command doesn't fail.  From the research that i've done it seems like there's a limit on how many ISL trunks you can configure on a 4500 series switch, but that really doesn't make any sence to me.

The ports are all unconfigured, there's a configuration on the switch, but this is the first time i've tried to setup the different interface configurations.

Jonathan

It is a limitation on that particular module. The first 2 ports are non-blocking and support either ISL or 802.1q trunking. The remaining 16 ports which are oversubscribed only support 802.1q trunking and so the "switchport trunk encapsulation ..." command is not available for those ports.

Jon

Re: Catalyst 4506 Problems

Jon is spot on !!!! hez just amazing

Just went through the datasheet of the module and found what Jon wrote.. First 2 ports are basically used for trunks and the reset are used more for fiber connected desktops/servers etc.. Four ports share 1 Gbps from 3-18... This is what it looks like (from datasheet):

The 16 oversubscribed ports (ports 3 through 18) are multiplexed in four groups of four ports each:

Ports 3, 5, 7, 9

Ports 4, 6, 8, 10

Ports 11, 13, 15, 17

Ports 12, 14, 16, 18

Thsi module is more targetted towards fiber to desktops, small server farms etc.. if you need fiber uplinks/trunks you need to look at modules like WS-X4624-SFP-E which can provide 24 x 1 gig line rate modules..

4500 line cards datasheet:

http://www.cisco.com/en/US/prod/collateral/modules/ps2710/ps5494/product_data_sheet0900aecd802109ea_ps4324_Products_Data_Sheet.html

Jon - 5 points from me on this...

Raj

Hall of Fame Super Blue

Re: Catalyst 4506 Problems

Thanks Raj.

I've been searching for the link that states this explicitly, because the other ports ie. 3 - 18 can still be trunked just not with ISL -

4500  module note

Jon


Re: Catalyst 4506 Problems

This was the best doc i could find for oversubscription ports.. Again, as you mentioned, they havent explicitely given about the trunk configs..

they just say to avoid connecting routers and switches to oversubscribed ports, and just to connect servers..

Raj

Hall of Fame Super Blue

Re: Catalyst 4506 Problems

Raj

Sorry for the confusion. In my last post there is a link to a doc that states it explicitly, knew i'd seen it somewhere

Jon

Community Member

Re: Catalyst 4506 Problems

Thank you both very much for the help.  Last question which i'm not sure if you can answer, why shouldn't you connect switches to oversubscribed ports, other than the obvious reason of sharing 1GBPS across 4 ports?  Are there potential problems that can occur?  There isn't much information on this but really, if it's recommended not to connect switches to these ports, i've got another 6 port GBIC blade that i can use.


Thanks again for all of your help!

Hall of Fame Super Blue

Re: Catalyst 4506 Problems

Jkloza wrote:

Thank you both very much for the help.  Last question which i'm not sure if you can answer, why shouldn't you connect switches to oversubscribed ports, other than the obvious reason of sharing 1GBPS across 4 ports?  Are there potential problems that can occur?  There isn't much information on this but really, if it's recommended not to connect switches to these ports, i've got another 6 port GBIC blade that i can use.


Thanks again for all of your help!

Jonathan

You could connect a switch if you wanted but then it would be recommended to leave the other 3 ports in that group not connected to anything. Obviously if you didn't as you say there would be oversubscription.

Jon

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