urgent problem

[alsayed]

Hi All!

yesterday;i've configured a switch with 4 port uplink(EtherChanel)in the side access switch,the channel mode is desirable but by mistake the persom who configured in side core mode chanel is on;then when accees switch startup we have received duplicate ip address.loop,error,and all the access switch down.what is the problem here?what is happen;when we turnOff this switch every thing is fine

10xs

Ali

10xs

Ali

[alsayed]

Hi

the config was like this in the access side:

interface GigabitEthernet0/25

switchport trunk encapsulation isl

switchport mode trunk

channel-group 5 mode desirable

........................................

interface GigabitEthernet0/26

switchport trunk encapsulation isl

switchport mode trunk

channel-group 5 mode desirable

....................................

interface GigabitEthernet0/27

switchport trunk encapsulation isl

switchport mode trunk

channel-group 5 mode desirable

...................................

interface GigabitEthernet0/28

switchport trunk encapsulation isl

switchport mode trunk

channel-group 5 mode desirable

..............................................

interface Port-channel5

switchport trunk encapsulation isl

switchport mode trunk.

10xs for ur reply

Ali

[devang_etcom]

ali look at this link :http://www.cisco.com/univercd/cc/td/doc/cisintwk/itg_v1/tr1923.htm#xtocid44

and read the table 23-4...may it will help you

regards

Devang

[alsayed]

Hi Friend!

10xs for ur reply!this link didn't include something about my problem.did u faced like this?where the Expert like Ankur to help Me.

10xs Friend

Ali

[leonvd79]

Devang pointed out that a channel cannot be formed with the configuration desirable-on.

The information from table 23-4 tells you to use either desirable-desirable, desirable-auto or on-on to successufully form a channel.

As you did not supply the remainder of the switch configuration we cannot determine what caused the problems you mentioned.

It's verly likely that with four redundant paths between your core and access layer a loop occured.

Check your spanning-tree configuration and supply sufficient information for further assistance.

May I remind you that help is on best effort basis. We are not here to help you promptly, be patient and polite and you might get what you need.

--Leon

[alsayed]

Hi

Sorry Friend!this the Second MOnth That i have working in Cisco Product!

1st)where i check the Spanning Tree?

2st)if the config on the access switch its desirable;and in the core(by mistake) the channel is on, make This big problem in the enterprise network.loop;servers no pingable?what can i do?

10xs

Ali

[mahmoodmkl]

Hi Ali

As a quick fix disconnect u r ports which are used in u r channel.And try to verify u r STP topology.

show spanning-tree

As in the above posts confure ur channel to desirable-desirable it is recommnded to avoid problems like which occured in ur case.and try to check the cables for a possible UDLD problem.

Thanks

Mahmood

[alsayed]

HI Mahmoud!

check the cables for a possible UDLD problem.what do u mean by this?

10xs

Ali

[leonvd79]

Cisco.com has a great documentation site: http://www.cisco.com/univercd/home/home.htm

For quick reference use Google: "UDLD site:cisco.com/univercd".

UDLD is used primarily on fiber optic linkd, to monitor bi-directional communication. In case of a transmit/receive failure a uni-directional connection occurs and will result into a L2 loop when redundant paths exist.

--Leon

[devang_etcom]

UDLD: udld protocol allow for detection of unidirectional link condition on switch ports in situation where a link remain in up state but the interface not passing traffice...this is most offent in GBIC or interface, software malfunction, hardware faliure or other any behaviour...

UDLD is l2 protocol and used to determine the physical status of link...with udld, switch periodicaly send the udld protocol packets to its neighbor and wait for the echoed back before predetermined time...and if echo will not receive switch determines the linke to be unidirectional and shuts down the port...

hope this will help you

ali i am just try my best to help you nothing more...and yes ankur is expert and i respect him and his help, he also help me lot...

rate this post if it helps

regards

Devang

[alsayed]

Hi devang!

10xs for ur reply,but PS Don't get me wrong.i have thanks every one help me.Devang;Ankur has a very good Description of the problem;and help how to fix it quikcly.

regards

Ali

[devang_etcom]

hi ali,

thanks for complement...and ya i also get good help form netpro form...and yes i also would like to share knolege ...as i am also learn lots of thing...because i also find some good issue which help me to learn or troublshoot in my work...

thanks again

regards

Devang

[jpason4309]

I might be missing something here, but if the core side was set to "on" by mistake, then why was it an issue to get into one of the two switches and just make them the same? Either desirable or on. Wouldn't that have fixed it very quickly?

regards,

jeff