SUMMARY: 2 Ethernet Cars/Same Ethernet Address

Date: Wed Nov 16 1994 - 12:08:04 CST

Hi Managers,

        Well, I should have checked the FAQ first, It had the answer I needed.
A few of you pointed that out to me. I've started to save off the Monthly FAQ
for myself.

A suggestion for the person who maintains the Gopher for the SUMMARIES:
        Please add the FAQ to the inquiry.
I did look there first, before posting the message.

Here's what the FAQ says:
12. Networking
Subject: 12.1) Why do both my interfaces have the same ethernet address?

  The Ethernet version 2.0 specification (November 1982) states:

          The physical address of each station is set by network
          management to a unique value associated with the station,
          and distinct from the address of any other station on any
          Ethernet. The setting of the station's physical address
          by network management allows multiple multiple data link
          controllers connected to a single station to respond to
          the same physical address.

  This doesn't normally constitute a problem because each interface will
  typically be on a different subnet. If, for some reason, different
  ethernet addresses are required on different interfaces (for example, to
  attach two interfaces to the same subnet), a new one may be assigned
  using the ifconfig command.


Some other information:
        - The ethernet address comes from the NVRAM, if the Lithium battery
          dies, the Ethernet, Serial Number and Hostid is lost.
        - The Address can be changed with the command:
                ifconfig le? ether #:#:#:#:#:#


Original Question:
> Hi Managers,
> We have a SPARCstation 10 with an additional Ethernet Card. Some
> of our engineers have been tracking a non network problem, by monitoring
> the packets on both networks. The noticed that the Ethernet address
> being reported on both networks were the same (8:0:20:21:a1:b5). They
> felt that since there were 2 physical cards, they should report different
> ethernet addresses. Every Sun that I have with 2 Network interfaces, report
> the same address. I know that this is the correct, we have no network
> problems, but they did not take my word for it, and I could not give them
> a good reason for this. Therefore, I'm asking for the reason,
> Why the Ethernet Addresses are the same?
> Thanks,

Thanks to the following:
        Tom Orban <> (Doug_Tassan)
        Scott McWilliams <> (joe merola)
        Casper Dik <> (Danny Johnson) (Hermann Kuhn) (Gary Blumenstein) (Kevin Sheehan {Consulting Poster Child}) (Tom Friscia) (Peter Samuel) (Ron Spillane) (Brett Lymn) (Jairo A. Medina)
        Mike Raffety <>
        Henrik Sloth <> (Perry Hutchison)
        Dave Mitchell <> (Trevor Morrison)
        Torsten Metzner <> (Tuan Quoc An) (Dan Zegarac)
        Salvatore Saieva <merccap!clark!> (Stephen Waelder)
        bobr@houston.wireline.SLB.COM ( Bob Reardon ) (James Chapman)
        Cheri Paavola 977-8585 <> (303)
        Darryl Wagoner-MIS Manager <> (Anthony (Tony) Reeves)
        John Goggin - LTX Tech Support <>
        James Ashton <> (Aaron Cammarata) (Russ Poffenberger) (Paul Roland)
        bern@TI.Uni-Trier.DE (Jochen Bern)
        Timothy G Smith - Special Projects <tgsmith@Sun.COM> (Birger A. Wathne) (Ken Burns)
        stern@sunrise.East.Sun.COM (Hal Stern - NE Area Systems Engineer)
        Dave Benson <>

   | John Cieply | HRB Systems |
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