Date: Tue, 03 Jul 2001 21:11:25 +0200 From: Thierry Herbelot <thierry@herbelot.com> To: Juan Fco Rodriguez Hervella <jrh@it.uc3m.es> Cc: Lista <freebsd-net@FreeBSD.ORG> Subject: Re: How to send packets to another interface on the same machine Message-ID: <3B4218DD.A1DAAB51@herbelot.com> References: <3B420C63.41C48FBB@it.uc3m.es>
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Juan Fco Rodriguez Hervella wrote: > > Dear all: > > I have the following problem: I would like to send an IPv6 packet using > a given > interface, to the address that corresponds to another interface of the > same machine. > > This, that seems a bit akward, it would be interesting for obtaining > accurate > packet latency results to test other systems that could be placed > between the > two interfaces (routers, etc.). Since the sending and the receiving > process share > the same physical clock, microsecond precision could be obtained in the > measures. > > The problem is that FreeBSD recognises that the destination address is > in the same > machine, and routes directly through the loopback interface, without > sending actually > the packets through the wire. > > Anyone knows a trick to do this? I have recently built a similar test bench, but for latency accuracies in the order of 1 ms (instead of some usecs), using ntp to synchronize the machines. This way, I could measure the the travelling time of packets down to a 1 ms accuracy (from one PC to another, both being synchronized to the same NTP master server) HtH -- Thierry Herbelot To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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