Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!uunet!pcserver2!kdenning
From: kdenning@pcserver2.naitc.com (Karl Denninger)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: all of the ethernets interfaces with the same address!?
Summary: This is why "ifconfig" takes an "ether" parameter... :-)
Message-ID: <1991Apr21.170045.21393@pcserver2.naitc.com>
Date: 21 Apr 91 17:00:45 GMT
References: <33874@boulder.Colorado.EDU> <1991Apr3.222527.3422@ultra.com>
Organization: AC Nielsen, Bannockburn IL USA
Lines: 36

In article <1991Apr3.222527.3422@ultra.com> shj@ultra.com (Steve Jay) writes:
>In <33874@boulder.Colorado.EDU> BILLW@mathom.cisco.com (WilliamChops Westfield) writes:
>
>>    In all TCP/IP implementations I know of, all ports on the
>>    same machine use the same ethernet (hardware) address.  On
>>    initialization, it reads the ROM on the first port it finds,
>>    and stores this in all the ports.  
>
>>No, this is incorrect.  In fact, I don't know of ANY TCP implementations
>>that do this

It is true on SOME machines -- primarially those which get their ethernet
address from the system PROM rather than from the board's PROM.

>From my neighborhood Sun server:
>
>	# ifconfig -a
>	le0: flags=63<UP,BROADCAST,NOTRAILERS,RUNNING>
> 	       inet 139.93.30.1 netmask ffffff80 broadcast 139.93.30.0
>  --->         ether 8:0:20:7:aa:77 
>	ie1: flags=63<UP,BROADCAST,NOTRAILERS,RUNNING>
>	        inet 139.93.1.8 netmask ffffff80 broadcast 139.93.1.0
>  --->          ether 8:0:20:7:aa:77 

Note that you can change that with "ifconfig ie1 ether xx:xx:xx:xx:xx:xx"

Not all values are valid for the hardware address, but enough are to make it
useful. (I usually change the "20" to "21").

--
Karl Denninger - AC Nielsen, Bannockburn IL (708) 317-3285
kdenning@nis.naitc.com

"The most dangerous command on any computer is the carriage return."
Disclaimer:  The opinions here are solely mine and may or may not reflect
  	     those of the company.