TCP Analyzer Questions and Feedback

[chpalmer]

Wondering if anyone else has problems with thier ISP and port 8080?? I can reach it fine in the ISP's network but not outside of it...

[Faction]

the analyzer isn't working for me right now

[cutebabe]

Hi Philip,
I used your tool , it seems good but I have some questions.
1. MTU value:
Here is my result:
MTU = 1472
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput. If you are using a router, it could be limiting your MTU regardless of Registry settings.

Why this tool can know the MTU value is 1472 . I donot know where to config the MTU value on my system, with Ethernet the default MTU value is 1500byte.

2. MTU Discovery (RFC1191) = ON => Please explain how your tool can detect that Path MTU discovery was turned on

I'm looking for your answers.
Thanks in advance !

[Philip]

This thread is intended for TCP Analyzer questions and feedback.

I am moving a few questions from the rules & announcements forum thread here as well.

[Philip]

Hi Philip,
I used your tool , it seems good but I have some questions.
1. MTU value:
Here is my result:
MTU = 1472
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput. If you are using a router, it could be limiting your MTU regardless of Registry settings.

Why this tool can know the MTU value is 1472 . I donot know where to config the MTU value on my system, with Ethernet the default MTU value is 1500byte.

2. MTU Discovery (RFC1191) = ON => Please explain how your tool can detect that Path MTU discovery was turned on

I'm looking for your answers.
Thanks in advance !

The TCP Analyzer looks at the TCP/IP packets coming from you to our server. It analyzes the TCP/IP headers, and extracts the MTU/MSS/RWIN... etc. values directly from there. In other words, it reports what is actually in the packets traveling on the internet.

MTU value is editable from within the Windows Registry for every network adapter, you can also use our TCP Optimizer tool. Note that regardless of Registry settings, routers on the line can also modify the MTU.

As for your second question about MTU discovery, again, it all depends on what your computer reports during the TCP/IP handshake with the Analyzer server.

I hope this helps.

[Philip]

the analyzer isn't working for me right now

There was a temporary problem on the 12th, we had to restart it. Thanks for the feedback.

[cutebabe]

The TCP Analyzer looks at the TCP/IP packets coming from you to our server. It analyzes the TCP/IP headers, and extracts the MTU/MSS/RWIN... etc. values directly from there. In other words, it reports what is actually in the packets traveling on the internet.

MTU value is editable from within the Windows Registry for every network adapter, you can also use our TCP Optimizer tool. Note that regardless of Registry settings, routers on the line can also modify the MTU.

As for your second question about MTU discovery, again, it all depends on what your computer reports during the TCP/IP handshake with the Analyzer server.

I hope this helps.

Thanks for your help. But I have more questions

1. Where is the MTU placed in protocol header ? As I know it is one value in Network Interface configuration. Is it true ?

2. If I use Ethernet(default MTU = 1500) and I change the MTU value in my registry, what will happen ?

[Philip]

I'm not sure I understand the relevance of your first question, but... The MSS is placed in the Tcp1323 Options (option 2) of the TCP header, and MTU is in the IP header (starting at the 16th bit ?). What is in the headers, and the MTU can't be modified directly from the Network Interface configuration. There can be, however, a MTU entry in the Windows Registry for each network device.

As to the second question: Ethernet supports packet sizes from 64 bytes to 1500 bytes (actually ~1518), so it will support 1472 as well as 1500. The 1472 in your case might be caused by a broadband router, if you haven't already modified the Windows Registry, so the better path would be to look through your router/modem's management interface for a way to increase it, rather than modifying Windows down to 1472.

[Bouncer]

To add:

1472 is also frequently a PPPoE packet size, because a too large a PPPoE packet will fragment, causing frequent data retransmissions, and thus, lower throughput. It's more or a safety feture so that the additional packet overhead by the additional headers is not going to cause the packet to exceed maximum packet length. This also applies to VPNs, though the actual packet length will be predicated on the length of the VPN header.

Regards,
-Bouncer-

[Philip]

Thanks Tom ...

Also... 1472 + 28 ( 20-byte IP and 8-byte ICMP headers) is the maximum size you can ping with, without fragmenting packets, assuming MTU of 1500... But that does not apply to the Analyzer (TCP + IP, not ICMP + IP), and MTU not MSS...

[cutebabe]

I'm not sure I understand the relevance of your first question, but... The MSS is placed in the Tcp1323 Options (option 2) of the TCP header, and MTU is in the IP header (starting at the 16th bit ?). What is in the headers, and the MTU can't be modified directly from the Network Interface configuration. There can be, however, a MTU entry in the Windows Registry for each network device.

Yes, I know that MSS(Maximum Segment Size) is placed in TCP Header, with this value when the packet reach Network layer the IP Total Length will not greater than the MTU value so that IP datagram donot need fragment. But I donot agree with you about the idea that MTU is in the IP Header. Starting at 16th bit until bit 31 is IP Total Length( IP header length + IP data length). I think it is not MTU value

[Philip]

You're right, I'm a bit rusty. Well, MTU depends on all the protocol headers involved anyway.

[girish]

i am new member.
i want to know what is MTU and how to use SG TCP optimizrer.
plz replay soon.

thanks in advance

[Philip]

MTU (maximum transmission unit) is the maximum possible packet size on your connection.

Here is some info on how to use the program:
http://www.speedguide.net/tcpoptimizer.php#using
http://www.speedguide.net/faq_in.php?category=100

[girish]

thanks philip

[girish]

TCP optimizer is not working.
how to backup TCP registry?
plz replay soon.

[lostcowboy]

I think its broken, when I click on the button I go to http://www.speedguide.net:8080/ but all I see is a blank screen.

[Philip]

The Analyzer server had locked up, thanks for bringing it up to our attention! Should be running now.