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| Title: | FDDI - The Next Generation |
|
| Moderator: | NETCAD::STEFANI |
|
| Created: | Thu Apr 27 1989 |
| Last Modified: | Thu Jun 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2259 |
| Total number of notes: | 8590 |
1679.0. "Problem sending packet with size > 4096 over TCP/FDDI" by COWBOY::MIRGHANE () Tue May 09 1995 16:13
We are running FDDI/TCP benchmarks:
machines: 2100 4/275 ( 1 or 2 CPUs) DIGITAL-UNIX V3.2 256 Mbytes
PCI FDDI.
We have a simple program ( socket client server send/recv )
the SO_SNDBUF SO_RCVBUF are sent to 280000
We have a problem when transmitting packet with a size greater
than 4096 bytes.
The receiving program (server) just cannot retrieve the packets at the speed
they are sent by the client.
Send routine return status:
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
status: =======================================: , 8192
Recv routine return status:
status: ======================================: , 8624
status: ======================================: , 4312
status: ======================================: , 4312
status: ======================================: , 4312
status: ======================================: , 4312
status: ======================================: , 8624
status: ======================================: , 4312
status: ======================================: , 8624
status: ======================================: , 4312
status: ======================================: , 4312
status: ======================================: , 4312
We do not understand why the receiving program retrieve
4312 with the recv routine and not bigger packets.
How can we correct this problem?
Thanks for a quick help.
SoumettY.
Soumetty.
| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1679.1 | | NETRIX::thomas | The Code Warrior | Tue May 09 1995 18:09 | 6 |
| Why do you think there is a problem? The largest IP packet allowed on FDDI
is 4352 bytes; subtract 40 for the TCP and IP headers and you get 4312.
Now when TCP receives data, it wakes up the receiver thread which copies
into the users buffer and returns. As long as there is any data, the read
will return; that means that the amount of data returned by read has little
bearing on the size of the writes on the transmitting side.
|
| 1679.2 | The problem is that the receiver do not get all the data | TLSE01::MIRGHANE | | Wed May 10 1995 14:01 | 10 |
| The problem is that I loose data. For example when I send 10 blocs of
8192 bytes. The receiver do get only something like 40 Mbytes instead
of the 80 Mbytes he should receive.
So this is a real problem isn't it. Thanks very much for your best
and quickest help.
Soumetty.
|
| 1679.3 | | NETRIX::thomas | The Code Warrior | Wed May 10 1995 15:02 | 4 |
| Note that the number of reads will not correspond to the number of writes.
Basically you need to read until you reach end-of-file.
(my guess is that the application is incorrectly written)
|
| 1679.4 | Yes the application is incorrectly written Thanks for help | TLSE01::MIRGHANE | | Wed May 10 1995 15:06 | 5 |
| You are right. number of reads was equal to number of writes.
Thank you very much.
Soumetty.
|