01-18-2006 11:39 AM - edited 03-03-2019 01:29 AM
I have a throughput issue on 3750's that I cannot find a reason for.
Here are the models and SW versions:
Switch Ports Model SW Version SW Image
------ ----- ----- ---------- ----------
1 28 WS-C3750G-24TS 12.2(20)SE C3750-I5-M
* 2 52 WS-C3750-48TS 12.2(20)SE C3750-I5-M
3 52 WS-C3750-48P 12.2(20)SE C3750-I5-M
I am encountering slow response between servers in one vlan and SOME clients in another vlan.
If I place a "SLOW CLIENT" in the same VLAN as the server (Same ports/cabling etc) the throughput problem goes away.
The intervlan routing takes place withing the stack itself and not externally.
I can find no reason for this behavior, CPU/Memory are well within limits.
I have been reading IOS release notes but can find no mention of this. I see no other people on this forum having similar issues.
Does anyone have any thoughts ?
01-18-2006 12:00 PM
If you have double checked the client and switchport settings to make sure they match exactly then I'm not sure . It could be something like this , at least soemthing to check.
CSCed30201 Bug Details
Headline Temporary Packet loss maybe exhibited by the switch - stack cable
Product IOS
Feature OTHERS Components Duplicate of
Severity 2 Severity help Status Resolved Status help
First Found-in Version none All affected versions First Fixed-in Version Version help
Release Notes
SYMPTOMS / CONDITIONS
Cisco has found occasional intermittent contact on the 3750 product
stacking cable when using the "Fox" labled speciified cables. The location
below shows a photograph of the label showing the word "Fox" printed on the
label.
Sjc-fs1\WG-D\DSBU-Escalation\Published\Bugs\CSCed30201\3750_Bad_Stacking_Cable_Label.doc
WORKAROUND:
These "Fox" labeled cables should be replaced. Contact Cisco's TAC and
request a cable only replacement.
No problem exists with the 3750 switch itself and should NOT be replaced.
The customer should be advised that the "Fox" labeled cable should be
destroyed so that the customer will not accidentally place the defective
cable back in service at some later time.
BACKGROUND:
Failures were found in Cisco's DSBU lab that cause an intermittency resulting
in reduced traffic speed.
Failure analysis was completed by the cable / receptical vendor. The failure
indicated a substandard design, with an out of tolerance tongue in the plug and
potential misalignment in the receptical. This vendor has been disqualified
at this time.
01-18-2006 12:47 PM
Unfortunately that particular stack of 3750's does not have a "FOX" cable. The switchport settings are good.
It is a very strange problem that has my users annoyed. On some ports it takes less than a second to open a 8MB Access DB file when the host is in the same subnet as the server, and greater than 10 seconds when in a different subnet.
There are no access lists, physical errors, CPU or Memory issues that I can find.
Thanks for that information however - that was new on me, I am having the rest of the network scoured as we speak.
01-18-2006 07:01 PM
If you are running mls qos.then could be CSCeg29704. I have seen this before.
-------------------------
Release Notes
After enabling QOS on 3750 and 3560 switches, certain application (mostly bursty
and TCP based) experience significant performance degradation due to unexpected
packet drops on some of the egress queues.
This is due to initial default egress queue threshold settings
(when qos enabled) not optimized for this type of traffic pattern.
This initial default queue threshold settings (when qos enabled)
thus need to be changed to accommodate these traffic.
Workaround:
Tune the egress queue thresholds parameters to
allocate more to the affected queues.
Specifically, egress queue 2 thresholds need to have the following settings:
Thresholds1 = 200
Thresholds2 = 200
Reserved = 50
Maximum = 400
e.g.
mls qos queue-set output 1 threshold 2 200 200 50 400
mls qos queue-set output 2 threshold 2 200 200 50 400
02-02-2006 02:27 PM
We do have mls qos turned on the switch.
This is the output of the "show mls qos queue-set" command:
Queueset: 1
Queue : 1 2 3 4
----------------------------------------------
buffers : 25 25 25 25
threshold1: 100 50 100 100
threshold2: 100 50 100 100
reserved : 50 100 50 50
maximum : 400 400 400 400
Queueset: 2
Queue : 1 2 3 4
----------------------------------------------
buffers : 25 25 25 25
threshold1: 100 50 100 100
threshold2: 100 50 100 100
reserved : 50 100 50 50
maximum : 400 400 400 400
Is it clear that we are running into this problem by the output above ?
02-18-2006 06:58 PM
Has this issue been resolved?? If not the issue may not be the switch but the type of data the clients and servers are sending(multicast). Can this be an application issue that requires a certain parameter in the interfaces turned on. Can you provide a configuration of the switch??
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