[ale] IP Aliasing (please help!)

[Jim Popovitch]

On Wed, 2005-05-18 at 19:00 -0400, Ryan Fish wrote:
> Jim,
> 
> I am still lost here.  So, using the IP ranges shown below, I can just add a
> range and everything will know where to route automagically?  I would need
> to actually add two then since I need to leave one IP (.203) out of the
> equation as it resides on the only name server that will be in place during
> the server migration that is causing my headaches at this time...

If you only have two IP addresses you don't need to use the -rangeX
method.  Sorry about suggesting that.  I would just alias eth0 to eth0:0
and use it.  The way to accomplish this is by copying ifcfg-eth0 to
ifcfg-eth0:0.  

The host can really only have one active default gateway.  You can add
multiples, but it will only use one of them based on the gw metric
setting.  However, are you sure that you need a second gateway or
special routing?

>From your configs below it doesn't look like you even need a second IP
address.  A host on one subnet should be able to access the server on a
second subnet assuming that there is a correct route on the switch(es)
that everyone is connecting to.

Alternatively, if still needed, you can add static routes on the server
in /etc/sysconfig/static-routes.

I'm still at a bit of a loss on your architecture, what is upstream from
that server, why are their two subnets, and do the two subnets already
have a route between them?

-Jim P.

> 
> The server with this temporary setup is a web server running Apache on RHEL3
> ES.  It is being used to serve a "We are working on things right now" page
> until the migration is complete.  This help make it make are more sense in
> any way?
> 
> -Ryan
> ----
>  
> > Subnet one
> > Network ID = xxx.xxx.242.192
> > Subnet Mask = 255.255.255.224
> > Default Gateway = xxx.xxx.242.193
> > Available IPs = xxx.xxx.242.195 - xxx.xxx.242.222
> > 
> > Subnet two
> > Network ID = xxx.xxx.242.224
> > Subnet Mask = 255.255.255.224
> > Default Gateway = xxx.xxx.242.195 (not sure how this can be though
> > since it is listed as a usable IP above)
> > Available IPs = xxx.xxx.242.225 - xxx.xxx.242.254
> 
> 
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