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Trouble with Cat 3750G-24TS

eh_ham
Beginner
Beginner

Hello,

I have built a LAN with Cat 2950G as access switchs and a Cat 3750G-24TS as backbone switch.

I am experiencing very low performances of the cat 3750G even with a very light trafic on LAN.

I have reinitialized it in factory configuration and checked every port condition using show interfaces command, the result is OK (ie no packet loss, very low load and no error).

But when I make a ping with -t option from a PC directly connected to the faulty switch it shows few lines with a transmission delay less than 1 ms followed by a line with delay too long and so on. But the switch still indicats no packet loss or any error.

The cabling is certified cat 6 and hase been checked.

The cat 3750G is running IOS release 12.1(14)EA1a

Can any one help me to find what's wrong.

Many thanks.

7 Replies 7

Prashanth Krishnappa
Cisco Employee
Cisco Employee

The problem description is very vague but I am gonna take a stab at it. Is both intervlan and intraVLAN traffic affected? What are you pinging? I suggest that you not just go by ICMP response times when pinging the switch. Try pinging another PC instead of the switch. Few things I would do.

*Have "switchport host" command on interfaces directly connected to PCs/servers/printers. This command enables STP portfast, disables channeling/trunking.

*Make sure your 3750 is the STP root switch

*Check for any incompatibility issues with your NIC cards and switch ports.

*Try upgrading the NIC drivers to the latest from the vendor.

*If you still have issues, open a TAC Case

Also, you might want to uprade your 3750/2950s to the latest 12.1(x) code.

Hello

Thanks for answering.

The switch 3750G is running in factory default configuration with only vlan1 configured as management interface and all ports attached by default to vlan1.

I have also tried to ping to an other PC directly connected to the switch and got the same result.

The PCs of the LAN are HP-Compaq PCs running XP professional recently updated with 10/100/1000 NICs configured to autonegotiate speed and duplex mode. The LAN connection status is indicating 1 Gbps.

Concerning STP, it is in its factory default configuration.

I am willing to upgrade IOS software release but have no access to image files for Cat 3750G on cisco.CCO (I am registered as guest user). Can you help me to get a new IOS software release.

Many thanks.

lawsonad
Beginner
Beginner

When pinging from the management interface on one of the 2950's to the 3750 do you see the same behavior?

Make sure STP is configured correctly (3750 hard set as STP root).

The IP address you were pinging from a PC with delay, is that a vlan interface on the 3750? Is the PC and IP in the same subnet/vlan routed across another vlan?

Hello and thanks for answering

STP is not configured (running in factory default configuration)

Only vlan1 is configured as management interface.

I have tried to ping from a PC directly connected to cat 3750G to IP adress of the switch and to IP adress of another PC directly connected to the switch with the same result.

PCs are running XP Pro and LAN status is indicating 1 Gbps connection.

Hello and thanks for answering

STP is not configured (running in factory default configuration)

Only vlan1 is configured as management interface.

I have tried to ping from a PC directly connected to cat 3750G to IP adress of the switch and to IP adress of another PC directly connected to the switch with the same result.

PCs are running XP Pro and LAN status is indicating 1 Gbps connection.

mcdonalda
Beginner
Beginner

Hi there,

I'm aware of an issue on that firmware version which can eat up all the CPU time.

Could you please advise the output from this command:

"show processes cpu | exclude 0.00"

Regards

Andrew McDonald

Hello,

please find hereafter the results of the command

'show processes cpu | exclude 0.00'

-----

CPU Utilization for five seconds 4%/0%, one minute 4%, five minutes 4%

PID Runtime(ms) Invoked uSec 5Sec 1Min 5Min TTY Process

-----

CPU Utilization for five seconds 4%/0%, one minute 4%, five minutes 4%

PID Runtime(ms) Invoked uSec 5Sec 1Min 5Min TTY Process

110 178254 435673 409 0.16% 0.10% 0 Spanning Tree

---------------

CPU Utilization for five seconds 4%/0%, one minute 4%, five minutes 4%

PID Runtime(ms) Invoked uSec 5Sec 1Min 5Min TTY Process

----------------

CPU Utilization for five seconds 4%/0%, one minute 4%, five minutes 4%

PID Runtime(ms) Invoked uSec 5Sec 1Min 5Min TTY Process

56 168 259 648 0.81% 0.18% 0.05% 1 Virtual Exec

110 178254 435673 409 0.16% 0.10% 0.10% 0 Spanning Tree

These are the most frequently displayed results.

Best regards.

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