Subject: RE: timeout value in TCP implementation

From: Mark Allman <[email-masked]>
Date: Mon, 21 Apr 2003 10:11:48 -0400

------- Forwarded Message

From: Bogdan Ghita <[email-masked]>
To: "'kunchanl '" <[email-masked]>
Cc: "[email-masked]'" <[email-masked]>
Subject: RE: timeout value in TCP implementation
Date: Sun, 20 Apr 2003 18:45:56 +0100

Hello Kun-chan,

3 seconds is the recomended initial value for the TCP timeout timer (RTO).
See RFC1122 (section 4.2.3.1) for details.

Cheers,
Bogdan

- -----Original Message-----
From: kunchanl
To: [email-masked]
Sent: 20/04/03 17:57
Subject: timeout value in TCP implementation

Hi,

    I've observed quiet a few of connections in my tcpdump trace
has the SYN packet re-transmitted after about 3 seconds (as
the example below). I'm wondering if this 3-second is related
some particular timeout value in some tcp implementaton. Can
anybody shed me some light?

Thanks
Kun-chan Lan

1036626828.477241 10.0.0.1.2355 > 192.168.0.2.80: S 12193306:12193306(0)
win 8192 <mss 1460,nop,nop,sackOK> (DF)
1036626831.460768 10.0.0.1.2355 > 192.168.0.2.80: S 12193306:12193306(0)
win 8192 <mss 1460,nop,nop,sackOK> (DF)
1036626831.784822 10.0.0.1.2355 > 192.168.0.2.80: . ack 3335637810 win
8760 (DF)
1036626831.792048 10.0.0.1.2355 > 192.168.0.2.80: P 0:758(758) ack 1 win
8760 (DF)
1036626831.852406 10.0.0.1.2355 > 192.168.0.2.80: . ack 124 win 8638
(DF)
1036626831.852423 10.0.0.1.2355 > 192.168.0.2.80: R 12194065:12194065(0)
win 0 (DF)

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