Slow file transfer, TCP windows size is too small

[Ha Dao]

Dear everybody

My lan campus has a Cisco C3560-IPBASE-M switch, when i connect 2 laptops into 2 ports, then try to copy a big file via FTP

I see the speed is very slow ( only about 2 - 5 mbps). When i use wireshark to capture i see the TCP windows size is about 200 to 700, and see many TCP dup ACK, TCP fast retransmission, TCP out of order ... ( see the attach file)

- show interface :  speed 100, duplex full, no errors

When i connect 2 laptops directly or via another switch ( ex 2960), the speed is about 95 mbps, TCP windows size is 65535 (maximum ). Everything is excellent.

How do you think about this case, what i should do

Tks so much

------

>sh ver

Cisco IOS Software, C3560 Software (C3560-IPBASE-M), Version 12.2(35)SE5, RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2007 by Cisco Systems, Inc.

Compiled Thu 19-Jul-07 18:15 by nachen

Image text-base: 0x00003000, data-base: 0x01100000

ROM: Bootstrap program is C3560 boot loader

BOOTLDR: C3560 Boot Loader (C3560-HBOOT-M) Version 12.2(25r)SEC, RELEASE SOFTWARE (fc4)

W_OFFC_1D_56.8 uptime is 2 years, 36 weeks, 4 days, 8 hours, 35 minutes

System returned to ROM by power-on

System restarted at 07:31:35 Hanoi Tue Mar 1 2011

System image file is "flash:c3560-ipbase-mz.122-35.SE5/c3560-ipbase-mz.122-35.SE5.bin"

cisco WS-C3560-48PS (PowerPC405) processor (revision Q0) with 122880K/8184K bytes of memory.

Processor board ID FDO1251Y0PR

Last reset from power-on

5 Virtual Ethernet interfaces

48 FastEthernet interfaces

4 Gigabit Ethernet interfaces

The password-recovery mechanism is enabled.

512K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address       : 00:24:51:25:68:00

Motherboard assembly number     : 73-9676-14

Power supply part number        : 341-0029-05

Motherboard serial number       : FDO125101SE

Power supply serial number      : LIT124603DA

Model revision number           : Q0

Motherboard revision number     : B0

Model number                    : WS-C3560-48PS-S

System serial number            : FDO1251Y0PR

SFP Module assembly part number : 73-7757-03

SFP Module revision Number      : A0

SFP Module serial number        : FDO12500N5S

Top Assembly Part Number        : 800-25859-04

Top Assembly Revision Number    : C0

Version ID                      : V05

CLEI Code Number                : COMU210ARA

Hardware Board Revision Number  : 0x01

Switch   Ports  Model              SW Version              SW Image

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

*    1   52     WS-C3560-48PS      12.2(35)SE5             C3560-IPBASE-M

Configuration register is 0xF

[Karthick Murugan]

Hi Ha Dao,

Do you see high CPU utilization as well during the transfer??

Ideally, the issue would be seen if the traffic is software switched(CPU) instead of hardware switched.

Thanks & Regards,
Karthick Murugan
CCIE#39285

[Ha Dao]

hi Karthick, CPU is normal ( about 10 % ), the MAC address table has about 800 entry, i think it is normal too

[Ha Dao]

note:

- 2 laptops install windows 7

- when i use iperf to test bandwidth i still get the maximum ( 50 Mbps)

[Karthick Murugan]

Hi Ha Dao,

Could you get the output of "show controller utilization | in interface?

Thanks & Regards,
Karthick Murugan
CCIE#39285

[Ha Dao]

Sure

show controllers utilization | include Fa0/9

Fa0/9              2                    0

show controllers utilization | include Fa0/10

Fa0/10             0                    2

show inter fa0/9

FastEthernet0/9 is up, line protocol is up (connected)

  Hardware is Fast Ethernet, address is 0024.5125.680b (bia 0024.5125.680b)

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

     reliability 245/255, txload 1/255, rxload 2/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 100Mb/s, media type is 10/100BaseTX

  input flow-control is off, output flow-control is unsupported

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input 10w5d, output 00:00:01, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 950000 bits/sec, 85 packets/sec

  5 minute output rate 169000 bits/sec, 180 packets/sec

     250423530 packets input, 108599456115 bytes, 0 no buffer

     Received 5988182 broadcasts (0 multicasts)

     0 runts, 290 giants, 0 throttles

     382917 input errors, 89226 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 3496032 multicast, 116 pause input

     0 input packets with dribble condition detected

     4088688820 packets output, 773896713239 bytes, 0 underruns

     0 output errors, 0 collisions, 9 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

show inter fa0/10

FastEthernet0/10 is up, line protocol is up (connected)

  Hardware is Fast Ethernet, address is 0024.5125.680c (bia 0024.5125.680c)

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

     reliability 255/255, txload 2/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 100Mb/s, media type is 10/100BaseTX

  input flow-control is off, output flow-control is unsupported

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input 00:05:57, output 00:00:00, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 51000 bits/sec, 68 packets/sec

  5 minute output rate 1055000 bits/sec, 206 packets/sec

     228555869 packets input, 118738348886 bytes, 0 no buffer

     Received 3478516 broadcasts (0 multicasts)

     0 runts, 415 giants, 0 throttles

     19 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 2075695 multicast, 318 pause input

     0 input packets with dribble condition detected

     7313025937 packets output, 982679165445 bytes, 0 underruns

     0 output errors, 0 collisions, 5 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

you can see the speed is too slow, i also recapture in wireshark

[Karthick Murugan]

I believe the ingress interface is Fa0/9 which see only 2% of traffic ingressing. Also looking at the "show interface output", I could see low reliability, CRC errors, Input errors. Although they look historical, the reliability is still a concern.

Could you try moving it to a different port or use a different cable?

Thanks & Regards,
Karthick Murugan
CCIE#39285

[Ha Dao]

oh my god, tks so much

i don't know why i didn't see it before

[Karthick Murugan]

No worries!!

Try moving to different port and check the status and if it helps please rate all the helpful postings.

Thanks & Regards,
Karthick Murugan
CCIE#39285