> From: Peter Jeremy <[EMAIL PROTECTED]>
> Date: 1999-11-01 17:49:29 -0800
> To: [EMAIL PROTECTED]
> Subject: Re: Ping - sized tests with 0% and 100% packet loss! Any
ideas?
> Cc: [EMAIL PROTECTED]
> X-Mailer: Mutt 1.0pre3i
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> X-Loop: FreeBSD.ORG
>
> At Tue, 2 Nov 1999 00:16:02 +0000, Josef Karthauser
<[EMAIL PROTECTED]> wrote:
> >Anyone any idea what's going on?
>
> The problem doesn't exist in 2.2.5-RELEASE. I can't readily test
> anything other than that and -current at present.
FWIW, our kernel, based roughly on FreeBSD 3.2, has the same line as
marked with "-", and I don't see the problem:
# for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
> do
> echo === $i ===
> ping -f -c 300 -s $i localhost
> done| grep loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
300 packets transmitted, 300 packets received, 0% packet loss
Regards,
Justin
> As far as I can determine, the problem with 1-byte packets is that
> the transmitted checksum is incorrect when the ICMP sequence number
> exceeds 255 - this suggests that the checksum missing the last byte
> of the sequence number. The problem is also on the transmit side.
>
> Studying the code in src/sys/netinet/ip_icmp.c:icmp_input() [which
> is reporting checksum errors] and icmp_send() [which inserts the
> checksum], it looks to me like the problem is:
>
> cvs diff: Diffing .
> Index: ip_icmp.c
> ===================================================================
> RCS file: /home/CVSROOT/src/sys/netinet/ip_icmp.c,v
> retrieving revision 1.37
> diff -u -r1.37 ip_icmp.c
> --- ip_icmp.c 1999/09/14 16:40:28 1.37
> +++ ip_icmp.c 1999/11/02 01:45:34
> @@ -685,7 +685,7 @@
> m->m_len -= hlen;
> icp = mtod(m, struct icmp *);
> icp->icmp_cksum = 0;
> - icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
> + icp->icmp_cksum = in_cksum(m, ip->ip_len);
> m->m_data -= hlen;
> m->m_len += hlen;
> m->m_pkthdr.rcvif = (struct ifnet *)0;
>
> though I can't confirm this immediately. (And I can't see why
> this would have worked at all).
>
> Peter
>
>
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>
--
Justin C. Walker, Curmudgeon-At-Large *
Institute for General Semantics |
Manager, CoreOS Networking | Men are from Earth.
Apple Computer, Inc. | Women are from Earth.
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