From owner-freebsd-questions@FreeBSD.ORG Mon Dec 4 18:20:19 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 9FF3E16A47C for ; Mon, 4 Dec 2006 18:20:19 +0000 (UTC) (envelope-from jona.joachim@free.fr) Received: from smtp4-g19.free.fr (smtp4-g19.free.fr [212.27.42.30]) by mx1.FreeBSD.org (Postfix) with ESMTP id 28B0843C9D for ; Mon, 4 Dec 2006 18:19:44 +0000 (GMT) (envelope-from jona.joachim@free.fr) Received: from localhost (4be54-4-82-234-154-189.fbx.proxad.net [82.234.154.189]) by smtp4-g19.free.fr (Postfix) with ESMTP id DD28789ED; Mon, 4 Dec 2006 19:20:17 +0100 (CET) Date: Mon, 4 Dec 2006 19:20:11 +0100 From: Jona Joachim To: a@zeos.net Message-ID: <20061204192011.430c3352@localhost> In-Reply-To: <20061204061444.GA653@host.my.domain> References: <20061203174849.GA4561@host.my.domain> <20061204061444.GA653@host.my.domain> X-Mailer: Sylpheed-Claws 2.6.0 (GTK+ 2.10.6; i386-portbld-freebsd6.2) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: How does my computer work with an empty arp table? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 04 Dec 2006 18:20:19 -0000 On Mon, 4 Dec 2006 08:14:44 +0200 a@zeos.net wrote: > On Sun, Dec 03, 2006 at 02:53:44PM -0800, Atom Powers wrote: > > On 12/3/06, a@zeos.net wrote: > > >My computer is connected to ISP via ADSL and works properly. > > > > > >I typed > > > > > >arp -a > > > > > >and saw an empty table, although I pinged successfully an Internet > > >host one second ago. > > > > The ARP table is a cache of known ARP<->IP addresses. If there are > > no addresses in the ARP table then the system will send out an ARP > > broadcast to discover the ARP address that belongs to the IP > > address. Of course only the Ethernet hosts on your local network > > will be in your ARP table. > > > > -- > > -- > > Perfection is just a word I use occasionally with mustard. > > --Atom Ray Powers-- > > Thank you for response. > > But why there is no MAC address of my ADSL modem connected via > Ethernet? Does my host send broadcast frames to communicate with > modem everytime? > > Furthermore, when I ping the modem, a proper entry appears in table: > > ------------------------------------------------------------------------ > $arp -a > > $ping -c 1 rt # It is my modem > PING rt.my.domain (192.168.1.1): 56 data bytes > 64 bytes from 192.168.1.1: icmp_seq=0 ttl=254 time=1.298 ms > > --- rt.my.domain ping statistics --- > 1 packets transmitted, 1 packets received, 0% packet loss > round-trip min/avg/max/stddev = 1.298/1.298/1.298/0.000 ms > > $arp -a > rt.my.domain (192.168.1.1) at 00:13:49:61:f9:b2 on rl0 [ethernet] > ------------------------------------------------------------------------ > > But no entry appears when I communicate trough the modem. Perhaps your modem works as a transparent bridge. Jona