Switch Access & Ping Problem

Unanswered Question
Feb 1st, 2010

Hi all

I have a very Variety problem to start with. Here We have a campus Network With total Switching and no routing scenario.

We have Cisco 4006 as a Core Switch and Cisco 2950 as access layer Switch . Here we dont have any VLANS or Trunking and all are in Single Vlan,Vlan1

Let's Cisco 4006 as SWITCH A and 2950 as SWITCH B and SWITCH C. Here is how they are connected

             1 Gbps MMF Connected using GBIC                   1Gbps MMF Connected through Media Converters               1Gbps MMF Connected through Media Converters

SWA------------------------------------------------------SWB-------------------------------------------------------------SWC---------------------------------------------------------------SWD

172.141.0.2/16                                      172.141.0.200/16                                           172.141.0.39/16                                              172.141.0.40/16

The problem is

1. When I Try to ping the SWB IP address from SWA though we have a 1Gbps OFC between the Ping Response is arouns 600 to 700 ms. Whereas when i try to ping any system connected to SWB the ping response is around 15 ms.

2. Intrestingly when I ping the SWB IP addresss from any System Connected to the same switch without the Uplink to Core switch (SWA) is 1ms and have very fine telnet session , When I reconnect the Uplink from the SWA to SWB the ping response from the System connected to SWB and to SWB is around 500ms and also telnet respnse is very slow 

3. Without the Uplink from the SWB to SWA the ping response to the SWC is also finr from Sys connected to SWB. As soon as i connect the Uplink from SWB to SWA the Ping Response Shoots to 500 Ms.

4.The SWC is connected to the SWD through 1 Gbps MMF OFC . I can See SWD as a Neighbor in the CDP table of SWC but i am not able to see SWC as a neighbor in SWD and also i am not able to ping SWD from SWC .

4.There is no problem in any of the OFC Segments as i throughly tested them with OTDR. I have even used brand new Fibre Connectors.

5. In all the Swithces STP is enabled and all are in VTP Transparent Mode.

6. As per my Observation i observed Rcv-Err Incrementing on the Error Counters over the SWB GBIC Interface and found no errors on the SWA GBIC Interface.

7.I have replaced with many Switches , Media Converters, GBIC's Suspecting the problem and found no use.

Kindly suggest me how to resolve it as i am left with no other option of Troubleshooting here after.

8.

I have this problem too.
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Ganesh Hariharan Mon, 02/01/2010 - 22:19

Hi all

I have a very Variety problem to start with. Here We have a campus Network With total Switching and no routing scenario.

We have Cisco 4006 as a Core Switch and Cisco 2950 as access layer Switch . Here we dont have any VLANS or Trunking and all are in Single Vlan,Vlan1

Let's Cisco 4006 as SWITCH A and 2950 as SWITCH B and SWITCH C. Here is how they are connected

           1 Gbps MMF Connected using GBIC                   1Gbps MMF Connected through Media Converters               1Gbps MMF Connected through Media Converters

SWA------------------------------------------------------SWB-------------------------------------------------------------SWC---------------------------------------------------------------SWD

172.141.0.2/16                                     172.141.0.200/16                                          172.141.0.39/16                                             172.141.0.40/16

The problem is

1. When I Try to ping the SWB IP address from SWA though we have a 1Gbps OFC between the Ping Response is arouns 600 to 700 ms. Whereas when i try to ping any system connected to SWB the ping response is around 15 ms.

2. Intrestingly when I ping the SWB IP addresss from any System Connected to the same switch without the Uplink to Core switch (SWA) is 1ms and have very fine telnet session , When I reconnect the Uplink from the SWA to SWB the ping response from the System connected to SWB and to SWB is around 500ms and also telnet respnse is very slow 

3. Without the Uplink from the SWB to SWA the ping response to the SWC is also finr from Sys connected to SWB. As soon as i connect the Uplink from SWB to SWA the Ping Response Shoots to 500 Ms.

4.The SWC is connected to the SWD through 1 Gbps MMF OFC . I can See SWD as a Neighbor in the CDP table of SWC but i am not able to see SWC as a neighbor in SWD and also i am not able to ping SWD from SWC .

4.There is no problem in any of the OFC Segments as i throughly tested them with OTDR. I have even used brand new Fibre Connectors.

5. In all the Swithces STP is enabled and all are in VTP Transparent Mode.

6. As per my Observation i observed Rcv-Err Incrementing on the Error Counters over the SWB GBIC Interface and found no errors on the SWA GBIC Interface.

7.I have replaced with many Switches , Media Converters, GBIC's Suspecting the problem and found no use.

Kindly suggest me how to resolve it as i am left with no other option of Troubleshooting here after.

8.

Hi Sreekanth,

what is the spanning tree output in switch A towards and the status of the ports which are connecting to switch B ?

Ganesh.H

sreekanth sarma Tue, 02/02/2010 - 00:35

The Spanning Tree for the port on SWA towards SWB is forwading State

and Similarly the Spanning Tree output for SWB towards SWA is also in forwarding State.

Ganesh Hariharan Tue, 02/02/2010 - 01:33

The Spanning Tree for the port on SWA towards SWB is forwading State

and Similarly the Spanning Tree output for SWB towards SWA is also in forwarding State.

Ok Let narrow down the problem as per your observation when ever you connect SW A to SW B everything goes high in responces,If yes can you check the any logs coming in SWB and what is show process CPU for SWB when SWA is connected.

Ganesh.H

sachinraja Tue, 02/02/2010 - 06:43

Hi Sreekant

Just wanted to get back on your network design... Any reasons why you keep cascading the switches multifolds ? Has this network worked good before and suddenly having issues ? Do you have ports on 4006, to terminate switches B, C, D directly, instead of cascading them ? with cascading you have a single point of failure scenario - with switch B failing users on switch C & D also lose network connectivity... this will also increase spanning tree instances and broadcasts on the network...

Regards
Raj

sreekanth sarma Tue, 02/02/2010 - 20:27

Hi Sachin & Ganesh

Thanks for your Help,

I did the observation of CPU and Memory Utilization after connecting the Trunk Link it was quite normal , but i noted a point before i connected the Uplink the CPU Utilization is 4% but after i connect it it,s about 8-9% , as far as i know on a 2950 Switch these values are normal ( i think).This may be due to large broadcast domain because of no VLANS and all the host under single /16 Subnet.If it would be a problem in the Switch why the Ping response from the SYS connected to SWB and Core Switch (SWA) is well fine and only to Management IP is slow?

I cannot directly connect SWC and SWD to SWA because these buildings are 1 Km apart from each other , as this netowrk is designed way back in 2000 there is no redundancy plan for failure. I cannot ask for new design because it would be a management Issue.

The setup is working fine for last 4 years with no issues , but suddenly all these thing happened.

I also found one log in the core swich 3 weeks ago " c4k-HOSTFLAPPING" between two interfaces where one being the SWB Uplink Interface, but after that it didn' happened.

Though the SWB is in VTP Transaprent Mode, the domain name of the VTP of SWB differs from SWA. Is it necessary to be same,if so how can i change the domain name?

Kindly look and suggest me further

Leonardo Schieder Thu, 10/07/2010 - 04:44

Hi!

I have a similar issue with a larger switched network. There are 3750, 2960 and 2950 switches in this network. The ping of several switches in the network is at about 500-600ms, the rest <10ms.

I wonder if you have found the solution to your problem, perhaps it would help me.

Regards, Leonardo

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