Date: Mon, 4 Dec 2006 08:14:44 +0200 From: a@zeos.net To: freebsd-questions@freebsd.org Subject: Re: How does my computer work with an empty arp table? Message-ID: <20061204061444.GA653@host.my.domain> In-Reply-To: <df9ac37c0612031453s31f91172wd07dc3a9c8e571b0@mail.gmail.com> References: <20061203174849.GA4561@host.my.domain> <df9ac37c0612031453s31f91172wd07dc3a9c8e571b0@mail.gmail.com>
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On Sun, Dec 03, 2006 at 02:53:44PM -0800, Atom Powers wrote: > On 12/3/06, a@zeos.net <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. How can I watch what is going on?
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