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New Member

pix 501 internet download throughput limited to 2.12 Mbit/s

Hi. A Pix-501 which is placed between an ADSL modem and gigabit router, makes the download speed from internet drop to 2.1 Mbit/s from 7 Mbit/s. Upload speed is not affected. Connecting router or pc/laptop directly to modem gives the ADSL line max. speed which is 7 Mbit/s. I checked all three devices in detail and there isn't any readable cue or sign which might lead to this problem. I checked all three devices' interfaces for CRC  and for 
other values and all seem normal if not zero. There isn't any two directly connected interfaces 
with different speeds such as half10 to full100 etc. Involved cables are also checked/replaced but they are all good branded, new Cat5, Cat5e, Cat6 cables. I was very happy to reinstall my lightly used, first hand device to protect my personal subnet but unfortunately if i cant resolve this problem which limits my internet download speed with 260 KBytes instead of 920 KBytes, I will have to retire it although always needed and not deserved in any other way. If you may 
help me on this issue I will be very happy. Please note that I'm a CCNA and IT person which might easier being helped. Thank you very much in advance and greetings.

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New Member

Hi. I couldn't get any

Hi. I couldn't get any comment my above message which is sent at least hoping a Cisco responsible might explain the reason of the problem even if there isn't a solution. So I thought to share some other known facts about the device which makes me insist about the case, hoping to resolve or understand it. 

I use the latest available: Cisco PIX Security Appliance Software Version 6.3(5)

According to Pix 501 specs table here are the speed related values:

Bidirectional firewall throughput (Mbps) 60 (my throughput is 2.1 Mbps with single computer)
3DES throughput (Mbps); VAC/VAC+ 3
AES-128 throughput (Mbps); VAC+ 4.5
AES-256 throughput (Mbps); VAC+ 3.4

I gave three encrypted speeds to compare with my value which is even below.

I know official support period for this device has ended and also this is not the correct place to find an official answer but unfortunately this is the only available medium to look. I believe, if this is not somehow specific to my device, many people over there somehow should aldready observed this issue before. Thank you for your help. Greetings all.

New Member

First of all a correction to

First of all a correction to my problem definition:

internet speed drop to 2 Mbit from 7 Mbit in case of:

- a video file watching

- test 


1- Be sure that all neighbor interfaces speeds are same such as 100full - 100full etc. for all involved devices.

2- Find a high speed ftp server on internet and confirm that your download speed is not affected. Or you may also setup a [localFTPserver - PiX - PC] and download a large file to confirm if NIC on PiX is healty.

4- If your PiX passes NIC health test and your FTP speed is at expected level then:

a- Disable filter activex 80 

b- Disable filter java 80

Each move will increase your speed between %20 - %40 and you will reach to your normal throughput.


1- You will be able to watch media at the speed your ISP provided.

2- result will show your ISP provided speed.

I won't speculate over the reasons but you are very welcome to do so to comprehend the issue better.

Hope helps, greetings.

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