- MAC address
- Posted by vlk on December 29th, 2005
Where would I find the MAC address for my USR Courier V90 modem?
- Posted by Paul Murphy on December 29th, 2005
"vlk" <sample@invalid.org> wrote in message
news:PjLsf.83854$3E2.6478@fe09.news.easynews.com.. .
56k dial-up modems. Whyu are you being asked for a MAC address?
Paul
- Posted by vlk on December 29th, 2005
"Paul Murphy" <p_murphynothanks@tospamhotmail.com> wrote in message
news:43b44e19$0$27189$ed2619ec@ptn-nntp-reader02.plus.net...
TCP/IP packets move over a network based on the MAC address. At some
point in the process, a MAC address must be used and it's got to come
from somewhere. My question is, "where would I find the MAC address for
my USR Courier V90 modem?"
- Posted by Moe Trin on December 30th, 2005
On Thu, 29 Dec 2005, in the Usenet newsgroup comp.dcom.modems, in article
<W3_sf.75422$5X.39702@fe05.news.easynews.com>, vlk wrote:
It has none. You are posting using Outlook Express, which means
windoze. If you look at the output of the "route print" command,
you may see some falsified information provided by microsoft claiming
to be a MAC address. It's actually some useless ASCII text that has
nothing to do with addressing.
No, that is only true on Ethernet and Token Ring. IP packets move over
the phone line using the ppp protocol (RFC1661) using IPIP (RFC1332).
As there is only one other host on the telephone wire (the peer at the
other end), a MAC address is not needed, nor used.
Old guy
- Posted by Tom Schmidt on December 30th, 2005
Modems do not have MAC addresses.
In the case of Ethernet each device on the local area network must have a
MAC address. The scope of the MAC address is limited to the LAN. MAC
addresses are not used on the Internet. Routers on the Internet have no idea
what MAC address is associated with a specific host. If that were the case
IP addresses would not be necessary. .
In the case of dialup most ISPs used Point-to-Point Protocol for
authentication and access. PPP is an encapsulation protocol that allows
network devices to communicate over a point-to-point physical connection
such as RS232 or dialup modem. In that case PPP assignees itself a dummy MAC
address. The MAC address exist only in the PPP stack.
/tom
"vlk" <sample@invalid.org> wrote in message
news:W3_sf.75422$5X.39702@fe05.news.easynews.com.. .
- Posted by Moe Trin on December 30th, 2005
On Fri, 30 Dec 2005, in the Usenet newsgroup comp.dcom.modems, in article
<pYitf.142$i65.85@trndny05>, Tom Schmidt wrote:
Welll... ppp is an encapsulation protocol that carries other network
protocols, such as IP, Novell IPX, Appletalk, etc. Start reading RFC1661
and the others it references, as well as
http://www.iana.org/assignments/ppp-numbers
A ppp packet over the wire consists of the following when carrying IP:
flag byte 0x7E
address byte 0xFF <------- ALWAYS
Control byte 0x03
protocol word 0x0021 IP datagram
"Information" 46 to 1500 byte IP datagram
CRC word 0xXXXX
flag byte 0x7E
So, where's the MAC? Compare that to an Ethernet frame (RFC894) on the
wire:
dest MAC 6 bytes
source MAC 6 bytes
type 2 bytes
"Information" 46 to 1500 byte IP datagram
CRC word 0xXXXX
Old guy
- Posted by Moe Trin on December 31st, 2005
On Fri, 30 Dec 2005, in the Usenet newsgroup comp.dcom.modems, in article
<pYitf.142$i65.85@trndny05>, Tom Schmidt wrote:
Sorry about that - wrong response. Actually, the ppp stack has no
need of a MAC address, so why should it create one that it's not going
to use?
The abortion known as PPPOE (PPP over Ethernet) has a MAC address, but
that's because it's running over the Ethernet stack. PPP never sees it.
And a minor correction of my response - the two byte "type" in the
RFC894 Ethernet frame should have been identified as '0x0800'
Old guy
