Need help setting MSS/MTU

Mr White · Post by **Mr White** » Thu Mar 22, 2001 7:09 am

Im lost the tcp/ip test keeps saying my MTU is set at 1454 even though i added the damn patch and rebooted. What am i doing wrong?
it was fine a few days ago but not now.
thanx

Lobo · Post by **Lobo** » Thu Mar 22, 2001 7:17 am

What do you want your MSS and MTU set too, your on PPPoE are you not

Lobo · Post by **Lobo** » Thu Mar 22, 2001 7:18 am

Please go to http://www.dslreports.com/tweaks and take test
turn off firewalls if you have one, take test and then click on results
Copy results by highlighting everything with mouse,
left button on mouse hold down and drag.
Copy results by hiting Ctrl & c, on keyboard, come back to Speedguide, to copy results from test in reply box, curor blinking at begining of box Hit Ctrl & v, on keyboard
Thank you

Lobo · Post by **Lobo** » Thu Mar 22, 2001 7:28 am

If you want to adjust your own do this, Windows will automattically set MSS 40 less than MAXMTU, 1500 MTU is not for PPPoE:
Please go to:http://www.dslreports.com/front/drtcp.html
Download DR. TCP to your desktop
Where it saids adapter settings, select your adapter
Where it says Windows sclaing- yes
Where it says Selective Acks-yes
Path MTU Discovery - yes
Black Hole Detection - No
TTL-64 or 32 (up to you) No affect on speed.
Set MAX MTU and MSS will be set
Where it says Time Stamping, no
click apply
Reboot for changes to take affect

Do not change any numbers in this box unless you know what you are doing.
A blank box only means that the default setting is being used

Mr White · Post by **Mr White** » Thu Mar 22, 2001 7:34 am

Thanx Lobo but i already got that dr.tcp and ive tried all that but it still comes up as my MTU 1454 on both tests? I want it set for 1492,i have PPPoE connection

[ 03-22-2001: Message edited by: Mr White ]

Mr White · Post by **Mr White** » Thu Mar 22, 2001 7:38 am

TCP options string = 0204058601010402

MTU = 1454
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput.

MSS = 1414
Maximum useful data in each packet = 1414, which is equal to MSS.
MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

Default Receive Window (RWIN) = 16384
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 16384
For optimum performance, consider changing RWIN to a multiple of MSS.
Other values for RWIN that might work well with your current MTU/MSS:
520352 (MSS x 46 * scale factor of 8)
260176 (MSS x 46 * scale factor of 4)
130088 (MSS x 46 * scale factor of 2)
65044 (MSS x 46)

bandwidth * delay product:
Your RcvWindow limits you to: 655.36 kbps (81.92 KBytes/s) @ 200ms
Your RcvWindow limits you to: 262.144 kbps (32.768 KBytes/s) @ 500ms
Consider increasing your RWIN value to optimize TCP/IP for broadband.

MTU Discovery (RFC1191) = ON

Time to live left = 117 hops
TTL value is ok.

Timestamps (RFC1323) = OFF

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349)= 00000000

Mr White · Post by **Mr White** » Thu Mar 22, 2001 7:42 am

Here is the tweak test..

Receive Window: 16384
Scaling: none
Path MTU Discovery: ON
RFC1323 Window Scaling: OFF
RFC1323 Time Stamping: OFF
Selective Acks: ON
MSS requested: 1414
TTL: 128
(less any hops behind firewall)
TTL remaining: 114

Example 146000 byte download
Actual data bytes sent: 146000
Actual data packets: 104
Max size packet sent: 1454
Max size packet recd: 1454
Retransmitted data packets: 0
sacks you sent: 0
pushed data pkts: 18
data transmit time: 1.981 secs
our max idletime: 179.5 ms
transfer rate: 52868 bytes/sec
transfer rate: 422 kbits/sec
transfer efficiency: 100%

ICMP quality readings
Minimum ping: 92 ms
Maximum ping: 99 ms
Ping stability:
97 98 94 93 95 99 95 97 95 92

Lobo · Post by **Lobo** » Thu Mar 22, 2001 7:46 am

Why is RWIN so small, what OS are you on, and yes your MTU should be 1492, maim page this site under registry Tweaks will explain how to change MTU will will change MSS, I want to know why RWIN is so small

Lobo · Post by **Lobo** » Thu Mar 22, 2001 7:48 am

You also have to reboot after making any changes wih Dr. TCP

Lobo · Post by **Lobo** » Thu Mar 22, 2001 7:53 am

You also need to turn Windows scaling ON with Dr.TCP

Mr White · Post by **Mr White** » Thu Mar 22, 2001 7:59 am

Yes i have rebooted and i did turn scalling on but it didnt change my mtu to 1492. I even looked in my registry and it says 0001-0009 all are MTU 1492... so is it set or is the test screwed up for me? Ill change RWIN

Mr White · Post by **Mr White** » Thu Mar 22, 2001 8:02 am

RWIN is small because window scaling is off and the rwin calculator said with speed of 1000kbits/latency 85ms =10625

Lobo · Post by **Lobo** » Thu Mar 22, 2001 8:04 am

Reboot computer after changing RWIN and retest, what OS

Lobo · Post by **Lobo** » Thu Mar 22, 2001 8:06 am

Scaling needs to be on

Mr White · Post by **Mr White** » Thu Mar 22, 2001 8:11 am

I have Win98,not SE.
Speeds look better now ,but why is the mtu still showing 1454??

Receive Window: 127776
Scaling: 1
Path MTU Discovery: ON
RFC1323 Window Scaling: ON
RFC1323 Time Stamping: OFF
Selective Acks: ON
MSS requested: 1414
TTL: 64
(less any hops behind firewall)
TTL remaining: 50

Example 146000 byte download
Actual data bytes sent: 146000
Actual data packets: 104
Max size packet sent: 1454
Max size packet recd: 1454
Retransmitted data packets: 0
sacks you sent: 0
pushed data pkts: 3
data transmit time: 1.490 secs
our max idletime: 169.4 ms
transfer rate: 53789 bytes/sec
transfer rate: 430 kbits/sec
transfer efficiency: 100%

ICMP quality readings
Minimum ping: 81 ms
Maximum ping: 87 ms
Ping stability:
83 86 83 86 85 81 85 84 86 87

Lobo · Post by **Lobo** » Thu Mar 22, 2001 8:18 am

Using Dr TCp select your adapter first, then set MTU to 1492, click apply, when it lites up, reboot, retest at our test and post back here, RWIN is not what patch set it at if patch is installed right, did you read how to install patch

Mr White · Post by **Mr White** » Thu Mar 22, 2001 8:26 am

Ive done that though,there is 3 adapters which one are you refering to? dlink,dial-up or pppoe adapter? the patch is installed properly now

Lobo · Post by **Lobo** » Thu Mar 22, 2001 8:29 am

Well if patch is installed right now it puts the right numbers in, if you reboot after installing patch, take our test after rebooting and post results:
1. Go to http://forums.speedguide.net/optd.shtml and click on check connection.
2. Copy all this by highlighting everything in box with mouse
(you may have to make box smaller. To copy contents of box, highlight, then hit Ctrl & c, on your keyboard, when you return to Speedguide in reply box, with cursor blinking, hit Ctrl & v, this will copy contents in box so I may look at it. Thank you.
X out your IP Address as we don't want world to know this info

Tweaking will not fix Packet Loss
Multiplayer games over UDP
Your regular ping time
Regular PC Freezes
impotence
Spike Lagg

Mr White · Post by **Mr White** » Thu Mar 22, 2001 8:32 am

Ok ive done everything you said

TCP options string = 020405860103030201010402

MTU = 1454
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput.

MSS = 1414
Maximum useful data in each packet = 1414, which is equal to MSS.
MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

Default Receive Window (RWIN) = 255552
RWIN Scaling (RFC1323) = 2 bits
Unscaled Receive Window = 63888
For optimum performance, consider changing RWIN to a multiple of MSS.
Other values for RWIN that might work well with your current MTU/MSS:
520352 (MSS x 46 * scale factor of 8)
260176 (MSS x 46 * scale factor of 4)
130088 (MSS x 46 * scale factor of 2)
65044 (MSS x 46)

bandwidth * delay product:
Your RcvWindow limits you to: 10222.08 kbps (1277.76 KBytes/s) @ 200ms
Your RcvWindow limits you to: 4088.832 kbps (511.104 KBytes/s) @ 500ms

MTU Discovery (RFC1191) = ON

Time to live left = 53 hops
TTL value is ok.

Timestamps (RFC1323) = OFF

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349)= 00000000

Lobo · Post by **Lobo** » Thu Mar 22, 2001 8:35 am

OK, on DR.TCP set time stamps to on, set dlink adapter to MTU 1492
and PPPoE adapter to MTU of 1492, retest

Mr White · Post by **Mr White** » Thu Mar 22, 2001 8:44 am

ok ive done that and rebooted and tested...same result

Lobo · Post by **Lobo** » Thu Mar 22, 2001 8:47 am

I read something a day or so ago on this , let me find it Mr. White and I will get back to you soon

Mr White · Post by **Mr White** » Thu Mar 22, 2001 8:49 am

should i reinstall my pppoe software? or what?

Lobo · Post by **Lobo** » Thu Mar 22, 2001 9:06 am

Here it is try this:
If your PPOE is Enternet software then the tweaks will not work go into your registry, and after backing up the registry go into
HOTKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Net\0002
under 0002 there is an entry for MaxFrameSize "1454"
change this number to "1492"
reboot and the recheck at Speedguides analyzer, if your pages wont load then drop this number by 2 at a time, but 1492 works perfect on mine
Leave the othert tweeks in place if you dont have any trouble.
--------------------

Lobo · Post by **Lobo** » Thu Mar 22, 2001 9:10 am

If the above works turn time stamps back off with Dr. Tcp, PPPoE adapter. reboot

Mr White · Post by **Mr White** » Thu Mar 22, 2001 10:14 am

Thank you Lobo it worked

I put this RAsopppoe thing on before but it didnt change anything so i put my access manager back in yesterday and then i had this problem do you think i did something to cause this screw up? i never went to that key that you showed me before.

Lobo · Post by **Lobo** » Thu Mar 22, 2001 10:19 am

Have to leave that for some of the DSL wiz guy's around here as I don't know

Lobo · Post by **Lobo** » Thu Mar 22, 2001 11:18 am

Here is the link to the thread I got that off of:http://forums.speedguide.net/cgi-bin/ul ... 4&t=000115