SUMMARY: Solaris 8 IP Multipathing with more than one IP

From: danix <>
Date: Thu Dec 20 2001 - 12:51:53 EST
Short answer:  Yes, it can be done.  Thanks to everyone who replied (I never mention names since some people want to remain anonymous, but I appreciate all replies).

Since there have been many questions lately about IP Multipathing, here are links to some docs:

I asked:
> I know that in Solaris8, you can use IP Multipathing (in.mpathd) to
> provide failover across a pair of ethernet interfaces.
> I also know that with 2 physical interfaces, you will need a 
> total of 4 IPs
> (two real, two dummy).  Only one is the "real" address that 
> talks to the 
> outside world, and would accept incoming traffic (so my DNS 
> would point to 
> this address).
> For this example, presume that the "real", visible IP is 
>, on
> hme0.  If hme0 fails, hme1 will take over with the same IP address.
> Now for my question:  in olden times, it was common to bind 
> more than one IP
> to a single ethernet interface, for purposes of Apache virtual hosts.
> Assume I still want to do virtual hosts that way.
> Is it possible in the multipathing example above, to have 
> more than one public
> IP bound to the active interface?
> To wit, can I have the machine such that:
>, 11 and 12 are on hme0
> if hme0 fails, all 3 IPs get moved to hme1
> I've reviewed all the docs from Sun and cannot find a 
> conclusive answer. 

Short answer:
Yes, it can be done.

Detailed answers:
all non-deprecated IPs move in a failure.
I have not tired this, but I believe that you would just have to add more
addif statements for the interface hme0 to give you the individual
virtual interfaces that you are looking for.  I would try this, but it 
would affect our production systems.. so I can't.  If this works,
please let me know so that I can use it!  Here is what I would think the
hostname.hme0 and hostname.hme1 would look like.

cador-hme0 netmask + broadcast + \
group production deprecated -failover up \
addif cador0 netmask + broadcast \
addif cador1 netmask + broadcast \
addif cador2 netmask + broadcast + failover up

cador-hme1 netmask + broadcast + \
group production deprecated -failover up \
addif cador3 netmask + broadcast \
addif cador4 netmask + broadcast \
addif cador5 netmask + broadcast + failover up

/etc/hosts	cador0	cador1	cador2	cador3	cador4	cador5	cador-hme0	cador-hme1

Just mark that interface with the 'failover' flag and it will be part of
the IPMP process.


$ cat hostname.hme0 <- dummy
bigbad1-test1 netmask + broadcast + group bigbad1 deprecated -failover up

$ cat hostname.hme0:1 <- real
bigbad1 netmask + broadcast + failover up

$ cat hostname.hme0:2 <- real
bigbad1-virt1 netmask + broadcast + failover up
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Received on Thu Dec 20 11:53:33 2001

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