Re: TcpDelAckTicks from PPC

anonymous_at_discussions.microsoft.com
Date: 02/18/04 

Date: Tue, 17 Feb 2004 20:16:18 -0800

Chris,

thanks for the response. My disclaimer "I know enough to
be misleading and be dangerous"

My assumption of the PPP is that it encapsulates the IP
packet to deliver it over "generally" a serial connection-
-modem.

I have a USB adapter connecting to the PPC that this
adapter is the USB Host (like the PC) and I route the
packet on the ethernet. So I get the PPP connection,
assign my IP address to the PPC, and from the point I
wrap and unwrap the packet appropriately in routing the
packets to/from the network for the PPC.

What I am seeing is that, if ActiveSync is the
application on the PPC, it is NOT sending the TCP Acks
UNTIL the default TCPDELACKTicks (.2s) expires. I see in
documentation that they INTEND to send ACKS for every
OTHER "segment" rx'd. I see this when OTHER applications
are rx'ing data from the network. But Activesync doesn't.

I see that the Activesync server is NOT sending TCP PUSH
flag with the data, and this MIGHT be the root of the
problem, but if I 'modify' the packet to the PPC, this
doesn't solve the issue, appears no change.

So, I was hoping that this setting would work. It
doesn't.

The other TCP setting of WindowSize does work, but doesnt
solve the problem either. Matter of fact, it can make it
worse.

IF -- I set the Windowsize to 1k, from the default size
of 32k, then activesync server is only able to send 1k
every .2 seconds = 5k bytes / second >>> very slow.
appears to be a BUG in their implementation??? Again,
this is without my adapter in the picture, just a
standard USB connection to the PC.

But this only appears to happen with ActiveSync.

Another part of my confusion might be in the
documentation. It refers to some of the settings
residing in the "adapter" tcp params. So I attempt to
set this settings in the PPP1, assuming this is the
adapter. If this is not the correct adapter, this would
explain why it doesn't impact it.

I fear that I am --- hosed.

any input would be great.

Mike
>-----Original Message-----
>Hi,
>ActiveSync uses the PPP stack when you sync and they
assign the ip address
>on the Pocket PC and the desktop as well as the wins
server, etc. I believe
>you are referring to parameters that are usually used on
regular network
>connections.
>
>
>--
>Chris De Herrera
>http://www.cewindows.net
>http://www.tabletpctalk.com
>
>"Mike" <anonymous@discussions.microsoft.com> wrote in
message
>news:101eb01c3f27f$4a90d540$a401280a@phx.gbl...
>> Does the tcpdelackTicks registry work for CE? it says
it
>> does, but I can't get it to work.
>>
>> When NOT using activesync, I copy a file to the PPC
and I
>> see the PPC do a ACK for generally every other packet,
>> just as it is documented.
>>
>> BUT when doing Activesync copy to the PPC, the PPC will
>> only ack at EVERY .2s interval. So if you change the
>> Windowsize registry to 1460 (the MSS), you will get 1
>> packet for every .2s, or 7k / second >>>> slow.
>>
>> I don't know why activesync is making the tcp behave so
>> differently. I also see in the SYN packet, the it
>> doesn't use the TimeStamp options, that it does when I
>> use the other file copy. Not sure if this relates??
>>
>> I see documentation that Win2000 need a patch to get
>> TCPDELACKTICKS to work, but nothing regarding CE.
>>
>> Any imput would be great.
>>
>> Mike
>>
>
>
>.
>

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