the overall response is that you can better not put the two interfaces on the same ethernet and thus not on the
same ip network. My original message is at the end of this mail.
I would like to thanks everyone who responded and especially Hal Stern (who gave the most complete answer to
my questions), Mike Raffety and Roar Smith.
email@example.com (Ed Strong)
"Douglas L. Acker" <firstname.lastname@example.org>
Geert Jan de Groot <email@example.com>
John Howie <firstname.lastname@example.org>
email@example.com (Fabrice Guerini)
"Bill Rea, University of Canterbury, New Zealand"
stern@sunne.East.Sun.COM (Hal Stern - NE Area Systems Engineer) responded with :
you cannot put two network interfaces on the same IP network.
it confuses the routing tables.
each network interface has the same ethernet address. this is
because ethernet addresses are assigned *per machine*, not
per interface. each netowrk interface has a different network
address (IP address). this requires that they be on different
networks: you can't have multiple interfaces to the same network.
when you set up le1 on the same network as le0, you create a
route to the le0 IP network -- but through le1. different IP
address, but same network route. therefore, packets outbound
from your machine go over le1 (the most recent route to the
IP network). this is likely to confuse things on the other side.
if you want redundant ethernet interfaces, leave le1 turned
"off" until you want it enabled. remove the /etc/hostname.le1
file, so it doesn't get ifconfig'd at boot time.
then write a script that periodically tests the network from the
machine. if it thinks it should switch over, have it
ifconfig le0 down
ifconfig le1 up
ifconfig le1 hostname ipaddress .....
this will "move" the IP address from le0 to le1, which is what
Mike Raffety <firstname.lastname@example.org> responded with :
No, you can't do this. If you're extremely familiar with TCP/IP and
internet addressing, it becomes apparent that this cannot work. Even
with different IP addresses on the two interfaces, any BSD-based IP
implementation will only be able to use one of the interfaces (due to
the way the routing tables are implemented).
I've never yet heard of an Ethernet interface going bad ... if it's
really, really important, dual-homed FDDI is the way to go here.
email@example.com (LMD/T/AM Roar Smith) resonded with :
In article AA09130@abcomp.be, wai-kong@abcomp.UUCP (Wai-kong Yu) writes:
>Is it allowed on a sunsystem to put both of your ethernetcards (I have
>a SS10 with a FSBE/S card, twisted pair) on the same physical ethernet network so that both of them or on the same IP net ?
There should as far as I know be no problem in doing this IF DIFFERENT
MEDIA ACCESS CONTROL ADRESSES ARE USED - i.e. different ethernet adresses.
>I tried it and it does work but sometimes I have problems.
>e.g. I can not do a telnet or rlogin anymore from my terminal server to
>my SS10. The terminal server can find the SS10's ethernetadres but connection
>will always fail. If I put the two cards on a different ethernet and IP network,
>it does work. Could there be a conflict somewhere ? I know that each
>sun has only one ethernet adres no matter how much ethernet cards you
>put in your system. Is there a special reason for this ?
The special reason is that Sun is ignoring the one rule, that all ethernet card
manufacturers must follow: There must never ever be two ethernet cards (in the whole
wide world!) with the same address.
It is unthinkable that anyone should break this rule, but alas - the unthinkable
happens all too often.
The reason (short version) is that the Data Link Layer of your network relies on
the MAC (Media Access Code) address of the node to be unique, if this is not the case
then the single node (ethernet card) cannot be uniquely addressed on the ethernet.
I have heard (not 100% safe info, I know) that Sun has allocated 20 ethernet
adresses for each of their SS10's, so you can/must configure your system with different
ethernet addresses on each card, either by hardware configuration (I don't have a
SS10, so I don't know if it's possible) or by software configuration.
To configure the system with different ethernet addresses on le0 and le1 you
can use the "ifconfig" command (in SunOS 4.1.x - I don't know about SunOS 5.x).
Your SS10 has the ethernet address 8:0:20:10:ab:30 (just an example).
In the /etc/rc.boot (or rc.local ?) file you use the "ifconfig" command for
setting up different ethernet addresses on le0 and le1:
# Set up different ethernet addresses on le0 and le1:
ifconfig le0 ether 8:0:20:10:ab:30
ifconfig le0 ether 8:0:20:10:ab:31
That's my $0.02 worth anyway.
My original mail :
Is it allowed on a sunsystem to put both of your ethernetcards (I have
a SS10 with a FSBE/S card, twisted pair) on the same physical ethernet network so that both of them or on the same IP net ?
I tried it and it does work but sometimes I have problems.
e.g. I can not do a telnet or rlogin anymore from my terminal server to
my SS10. The terminal server can find the SS10's ethernetadres but connection
will always fail. If I put the two cards on a different ethernet and IP network,
it does work. Could there be a conflict somewhere ? I know that each
sun has only one ethernet adres no matter how much ethernet cards you
put in your system. Is there a special reason for this ?
Another strange thing is that if I ping to le0 or le1 (the onboard ethernet
and second ethernet card), it is always le1 who responds. The same for telnet
and rlogin. Why ?
I want to be sure that all of my users can still access the SS10 server if there
should be a problem with one of my ethernet cards.
What is the best system configuration to assure a maximum reability and uptime
for my SS10 server ? Online disksuite is alreaddy installed.
Thanks for your help.
A summary will follow later.
e-mail : firstname.lastname@example.org
This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:07:27 CDT