> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] > Sent: Monday, 4 December 2006 2:15 PM > To: freebsd-questions@freebsd.org > Subject: Re: How does my computer work with an empty arp table? > > > On Sun, Dec 03, 2006 at 02:53:44PM -0800, Atom Powers wrote: > > On 12/3/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> 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? >
You can see what's going on by su'ing to root, and typeing: tcpdump -ni rl0 then try pinging, or sending your traffic. You will then see the ADSL modem reply (or the PPoE traffic etc). Cheers, Paul _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"