Topic:MSS + MTU down by [8] on nt5 aDSL_PB [Archive] - SpeedGuide.net Broadband Community

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heinz57
06-04-01, 09:47 PM
Topic: MSS + MTU down by [6] on nt5 aDSL_PB
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1,333.3 down 112 up (aways) so far. no down time

Could not get my MSS up till I swiched to Me.
Low by {6] on 2000 same on 98se.

On ME I installed EnterNet300 v1.5
Fixed .inf files before install.
Patchs and ajusted REG.I got MSS=1452 MTU=1492

I should start a post on all the steps.
Check it out at 18,480 Feet from (CO) not bad !

TCP options string = 020405ac0103030301010402
MTU = 1492
MTU seems to be optimized for PPPoE...

MSS = 1452
Maximum useful data in each packet=1452,which is equal to MSS.
MSS is optimized for PPPoE.

Default Receive Window (RWIN) = 511104
RWIN Scaling (RFC1323) = 3 bits
Unscaled Receive Window = 63888
RWIN is a multiple of MSS
Other values for RWIN that might work well with your current MTU/MSS:
255552 (MSS x 44 * scale factor of 4)
127776 (MSS x 44 * scale factor of 2)
63888 (MSS x 44)
bandwidth * delay product:
Your RcvWindow limits you to: 20444.16 kbps (2555.52 KBytes/s) @ 200ms
Your RcvWindow limits you to: 8177.664 kbps (1022.208 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 44 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349)= 00000000

xWinFire 384k ANY other DSL service is better !

[ I am on nt5 same fixes but only getting MSS=1446 MTU=1486.]
May be that PB allows Me to be right But win2k to be lower [-6]

Anyone runing nt5 EnterNet_1.5 aDSL 1.5m AMD 800 512m
who had same problem. Any REG. fix I missed HELP !
ASI wants to know what the fix turns out to be.

[Any help?] Thank You Much

cablenut
06-05-01, 04:36 AM
PPPoE uses 8bytes for encapsulation thus your Maxmium Transfer Unit is reduced to 1492bytes.

Enternet is a weird piece of software in their .inf config file they limit your MTU/MSS for some apparent reason (probably to be compatiable with all PPPoE suscribers?)

You have to modify this file to gain the full MTU.

Link to Enternet Mod:
http://www.broadbandnuts.com/pppoe.shtml