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improving download/upload speed on catalyst 6509

cisco24x7
Level 6
Level 6

LinuxES-lab1: 192.168.15.110/24

LinuxES-lab2: 192.168.15.100/24

Win2k3-1: 192.168.15.111/24

All 3 devices are connected to a Cisco Catalyst 6509 with sup-32 and

copper Gigabit Ethernet interface. All 3 devices are dell servers.

lab1 is dell 2550 dual processors 3.0 Ghz with 2GB RAM.

lab2 and Win2k3-1 are dell quad processors 3.1Ghz with 4GB RAM.

Everything on the switch and the interfaces on the server is

hard-code to 1000/full.

I have an FTP Server and Iperf running on LinuxES-lab2. When I

tested iperf from lab1, I get about 856Mbps throughput:

[root@LinuxES-lab1 tmp]# iperf -c 192.168.15.100 -t 10

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

Client connecting to 192.168.15.100, TCP port 5001

TCP window size: 16.0 KByte (default)

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

[ 3] local 192.168.15.110 port 32877 connected with 192.168.15.100 port 5001

[ ID] Interval Transfer Bandwidth

[ 3] 0.0-10.0 sec 1020 MBytes 856 Mbits/sec

[root@LinuxES-lab1 tmp]#

When I tested from Win2k3-1, I get about 600Mbps throughput.

However, when I download a 2GB file from lab1 to lab, I get only

about 325Mbps. If I used Secure Copy (scp), I get only about 72Mbps.

If I used Secure FTP (sFTP), I only get about 24Mbps.

Is there a way to improve the download speed for FTP, scp and sFTP?

Thanks.

29 Replies 29

pciaccio
Level 4
Level 4

One thing you could try is Jumbo Frame size. Set your MTU on these devices to a larger value then the default 1500 size. This will increae the data troughput. Since you can squeeze more data onto a packet with the increased MTU size then the IP overhead is decreased because less packets need to be sent over the line. Refer to attached for further details...Good Luck..

Unfortunately, the blade I have on the 6509 does

NOT support jumbo frame. It is a 10/100/1000

PoE blade. I am aware of the jumbo frame

but could not implement with my 6509.

Any other ideas? Thanks.

CCIE Security

Your board should support Jumbo Frame. Go to the Gig Interface and type MTU 9198 for the interfaces you are concerned about. Also make sure that your NIC cards support Jumbo frames as well....

Joseph W. Doherty
Hall of Fame
Hall of Fame

If you haven't already, you might review the articles under "Here are some additional links you may find useful" within http://dast.nlanr.net/Projects/Iperf/ Also, insure you have the latest NIC drivers on your hosts.

"f you haven't already, you might review the articles under "Here are some additional links you may find useful" within http://dast.nlanr.net/Projects/Iperf/ Also, insure you have the latest NIC drivers on your hosts."

I have the latest NIC drivers because I personally recompile my linux kernel. The driver is good. Otherwise, I would not get

856Mbps throughput with Iperf.

Take a look below, my catalyst 6506 gig blade

does NOT support jumbo frame. See below:

S65-1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

S65-1(config)#int g1/31

S65-1(config-if)#mtu ?

% Unrecognized command

S65-1(config-if)#mtu

S65-1#sh ver

Cisco Internetwork Operating System Software

IOS (tm) s3223_rp Software (s3223_rp-ENTSERVICESK9_WAN-M), Version 12.2(18)SXF4, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2006 by cisco Systems, Inc.

Compiled Thu 23-Mar-06 18:30 by tinhuang

Image text-base: 0x40101040, data-base: 0x42D20000

ROM: System Bootstrap, Version 12.2(17r)SX3, RELEASE SOFTWARE (fc1)

BOOTLDR: s3223_rp Software (s3223_rp-ENTSERVICESK9_WAN-M), Version 12.2(18)SXF4, RELEASE SOFTWARE (fc1)

S65-1 uptime is 19 weeks, 19 hours, 27 minutes

Time since S65-1 switched to active is 19 weeks, 19 hours, 26 minutes

System returned to ROM by power-on (SP by power-on)

System image file is "bootdisk:s3223-entservicesk9_wan-mz.122-18.SXF4.bin"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

cisco WS-C6506-E (R7000) processor (revision 1.0) with 983040K/65536K bytes of memory.

Processor board ID SAL1003AFTB

R7000 CPU at 300Mhz, Implementation 0x27, Rev 3.3, 256KB L2, 1024KB L3 Cache

Last reset from power-on

SuperLAT software (copyright 1990 by Meridian Technology Corp).

X.25 software, Version 3.0.0.

Bridging software.

TN3270 Emulation software.

16 Virtual Ethernet/IEEE 802.3 interfaces

96 FastEthernet/IEEE 802.3 interfaces

57 Gigabit Ethernet/IEEE 802.3 interfaces

1915K bytes of non-volatile configuration memory.

65536K bytes of Flash internal SIMM (Sector size 512K).

Configuration register is 0x2102

S65-1#

S65-1# sh mod

Mod Ports Card Type Model Serial No.

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

1 48 48 port 10/100/1000mb EtherModule WS-X6148-GE-TX SAL1003ASWV

5 9 Supervisor Engine 32 8GE (Active) WS-SUP32-GE-3B SAL1016KKWC

Mod MAC addresses Hw Fw Sw Status

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

1 0016.c7ed.7d98 to 0016.c7ed.7dc7 1.1 7.2(1) 8.5(0.46)RFW Ok

5 0016.c7ae.2f82 to 0016.c7ae.2f8d 4.2 12.2(18r)SX2 12.2(18)SXF4 Ok

Mod Sub-Module Model Serial Hw Status

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

5 Policy Feature Card 3 WS-F6K-PFC3B SAL1016KP28 2.1 Ok

5 Cat6k MSFC 2A daughterboard WS-F6K-MSFC2A SAL1016KG48 3.0 Ok

Mod Online Diag Status

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

1 Pass

5 Pass

S65-1#

Anymore ideas folks? Thanks.

CCIE Security

You might want to consider changing the TCP window size to force TCP to put more data in play, since jumbo frames are not an option. I try and steer clear of this in production, especially in a multi-OS environment, because flows that must go over the internet usually take a performance hit over internal flows. But! If this is an internal server and you have the time to tweak it, take a look:

http://dsd.lbl.gov/TCP-tuning/

HTH,

Geoff

window size - and buffer sizes - sorry that wasn't clear, lol.

Geoff

Geoff,

"window size - and buffer sizes - sorry that wasn't clear, lol."

I already made modification to these settings

in the /proc directory according to Linux

documentation. I still can NOT scale sFTP

pass 24Mbps and scp pass 80Mbps throughput.

I would imagine if I have issues with the

windows size and buffer sizes, then Iperf

would NOT have shown a 858Mbps throughput.

Anymore ideas? Thanks.

CCIE Security

A possible consideration, you're using Iperf with the implication that all other software using TCP should obtain similar performance. It could be as simple as the applications themselves are the root of the poorer performance, especially two that are performing on-the-fly(?) encryption.

PS:

Re: my earlier mention of NIC drivers, I also had in mind the lower Iperf(?) performance you saw with Win2k3-1.

i totally agree. ultimately if its not the tcp stack and not the networking devices we have to look at the remaining culprit - the software.

You might want to look at a time/sequence graph and see if the flows are steady - if not, you may have an implentation/encryption problem.

"especially two that are performing on-the-fly(?) encryption. "

That could very well but highly unlikely because

I performed "vmstat 1" on both linux boxes while

the transfer is taking place, the CPU is running

at 90% IDLE. In other words, the box has plenty

of cpu horse power left. One other thing, I

am using ssh with aes-128 encryption so the

encryption algorithm is very efficient.

Anymore ideas? Thanks.

Low CPU utilization, might rule that out as a bottleneck. That's assuming all CPU consumption is correctly accounted.

There are other system interactions that can lead to poor application performance. How the application reads and writes to disk, how the application bounces around within its working set, how the application reads and writes to the network. There's also how the system supports such. (An example of how extreme this can get, some computer architecures deliver different performance depending on how reads/writes to RAM are aligned on byte and/or word boundaries.)

"That's assuming all CPU consumption is correctly accounted".

I used "vmstat 1" to measure cpu utilization.

This low CPU utilization is consistent with

what I see nagios and solarwinds.

The Linux Server is running on a 10k RPM 100GB

RAID 5 drive so I dont' think reading/writing to

the disk is an issue.

David

I appreciate what you said about iperf results but where are your servers patched into the WS-X6148-GE-TX.

The WS-X6148-GE-TX is a heavily oversubscribed blade ie. it has an oversubscription rate of 8:1 so for every 8 ports there is maximum throughput of 1Gbps.

The port groupings are

1 - 8

9 - 16

etc..

so if you haven't already you may want to ensure that each of your servers has a port group to itself.

As i say i appreciate your iperf results but this may be worth a try.

Jon

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