Cat 4006 To Cat5500 Trunking Problem ?

[ChapFromBlighty]

We have a cat 4006 connected to a Cat 5500 Switch via 1Gb Full Duplex Trunk. Using Cisco's ISL Encapsulation. the 4006 is running 12.1(20)e and the Cat 5500 is running 5.5(19).

Our problem is that users connected to the 4006 have trouble logging onto MS Servers. But are able to ping those servers and resolve those servers names. When we placed an analyser on the network it became apparent the switch had stopped passing UDP Frames. Which explained why those users could not log on. The configs on both switches are correct and no errors show up in either logs. TCP traffic is fine

Has anyone come across this fault ? There are no bugs listed on Ciscos Website..

Cheers

Chap

 

[baddos]

Are you using any access-lists?

 

[ChapFromBlighty]

Hi

No access-lists at all. We have also found that if we disable and re-enable the trunks ports at both ends resolves the issue, for a while anyway..

Chap

 

[IPKONFIG]

The 4006 does not support ISL. You need to run Dot1q. May have to look into upgrading your Cat5500.

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[IPKONFIG]

Are your SUPs II's, III's or IV's?

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[baddos]

My 4006 running IOS 12 supports ISL.

Anyways I wouldn't think a trunking problem would cause all BUT UDP traffic to flow.

 

[IPKONFIG]

Yeah, if it has a SUP III or higher, it will support ISL. SUP II or lower will not.

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[ChapFromBlighty]

Hi

Both switches ie the 4006 & 5500 have Sup III modules and are both configured to run ISL. we have just experienced the problem again and a reset of the trunk ports (Disable/Re-enable) has resolved the issue again..Until the next time... It is 1Gb Trunk running in Full Duplex Mode. I wonder if the 5500 is having problems running with a Gb module (WS-U5536) in the Sup III Blade.??

 

[baddos]

Can you post the configs of the trunk interfaces?

 

[ChapFromBlighty]

Cat 5500

module 1 : 2-port 1000BaseLX Supervisor
set trunk 1/1 desirable negotiate 1-1005

set trunk 1/2 desirable negotiate 1-1005




Cat 4000
interface Port-channel5
switchport
switchport trunk encapsulation isl
switchport mode trunk
!
interface Port-channel10
switchport
switchport trunk encapsulation isl
switchport mode trunk

interface FastEthernet3/1
switchport trunk encapsulation isl
switchport mode trunk
speed 100
duplex full
udld port
channel-group 5 mode desirable
!
interface FastEthernet3/2
switchport trunk encapsulation isl
switchport mode trunk
shutdown
speed 100
duplex full
udld port
channel-group 5 mode desirable

 

[baddos]

FastEthernet3/1 and 3/2 are 1000Base LX?

 

[IPKONFIG]

I think you nailed it Baddos.

"I can picture a world without war. A world without hate. A world without fear. And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

 

[vipergg]

For the 5500 you might want to try hardcoding the trunking to ISL instead of negotiate . Have you looked at the bug toolkit on cisco for any known problems .

 

[baddos]

Yeah... I haven't used the 5000/5500 series switches before, but you might want to try upgrading it to 6.4 build. I see you have a current 5.5 build, but maybe there is something in 6.x that helps it interoperate w/ IOS switches.

 

[ChapFromBlighty]

Darn, sorry lads its been a long day, I have copied in the wrong interfaces on the 5500. Here are the correct ones and the are not 1Gb Trunks as first said they are 100Mb Full Duplex Channelised links

6/7 Trunk To Switch3A connected trunk normal full 100 10/100BaseTX
6/8 Trunk To Switch3A connected trunk normal full 100 10/100BaseTX

6/7 desirable isl trunking 1
6/8 desirable isl trunking 1