TCP Analyzer Questions and Feedback

chpalmer · Post by **chpalmer** » Sun Feb 12, 2006 7:11 pm

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 · Post by **Faction** » Sun Mar 12, 2006 8:03 pm

the analyzer isn't working for me right now

cutebabe · Post by **cutebabe** » Tue Mar 14, 2006 5:14 am

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 !

Post by **Philip** » Tue Mar 14, 2006 9:19 am

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.

Post by **Philip** » Tue Mar 14, 2006 9:39 am

cutebabe wrote: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.

Post by **Philip** » Tue Mar 14, 2006 9:40 am

Faction wrote: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 · Post by **cutebabe** » Tue Mar 14, 2006 2:51 pm

Philip wrote: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 ?

Post by **Philip** » Tue Mar 14, 2006 4:01 pm

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 · Post by **Bouncer** » Tue Mar 14, 2006 5:08 pm

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-

Post by **Philip** » Tue Mar 14, 2006 6:04 pm

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 · Post by **cutebabe** » Wed Mar 15, 2006 3:25 am

Philip wrote: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

Post by **Philip** » Wed Mar 15, 2006 9:01 am

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

girish · Post by **girish** » Fri Mar 31, 2006 12:59 am

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

thanks in advance

Post by **Philip** » Fri Mar 31, 2006 11:13 am

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 · Post by **girish** » Sat Apr 01, 2006 1:00 am

thanks philip

girish · Post by **girish** » Wed Apr 05, 2006 1:22 am

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

lostcowboy · Post by **lostcowboy** » Fri Jul 06, 2018 6:44 pm

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.

Post by **Philip** » Fri Jul 06, 2018 10:25 pm

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

SG Broadband Community

TCP Analyzer Questions and Feedback

Question about MTU value

TCP Analyzer Questions and Feedback

hello