Creating Aliases in Domains

Creating Aliases in Domains

[Phil Carinhas]

  FYI,

  This may be known, but I discovered how to create an alias interface
  for a domain. Using the same gateway as the primary nic
  doesn't work for a Debian-stable xenU. Using the network number
  the bridge IP, or the primary eth0 number seems to work ok:
  

iface eth0 inet static 
  address 214.213.44.21
  netmask 255.255.255.240
  gateway 214.213.44.17

iface eth0:1 inet static 
  address 214.213.44.22
  gateway 214.213.44.21 (or .18 which is the Xen0 ip)
  netmask 255.255.255.240

 The alias (virtual if) is routing to the bridge.
 If you see a better way please share.

-Phil Carinhas
--
 .--------------------------------------------------------.
 | Dr. Philip A. Carinhas       | pac(at)fortuitous.com   |
 | Fortuitous Technologies Inc. | http://fortuitous.com   |
 | Linux Networking & Security  | Tel : 1-512-351-7783    |
 `--------------------------------------------------------'


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Re: Creating Aliases in Domains - Solution?

[Phil Carinhas]

On Thu, Nov 11, 2004 at 11:57:03PM -0600, Phil Carinhas wrote:
>   FYI,
> 
>   This may be known, but I discovered how to create an alias interface
>   for a domain. Using the same gateway as the primary nic
>   doesn't work for a Debian-stable xenU. Using the network number
>   the bridge IP, or the primary eth0 number seems to work ok:
> 
> iface eth0 inet static 
>   address 214.213.44.21
>   netmask 255.255.255.240
>   gateway 214.213.44.17
> 
> iface eth0:1 inet static 
>   address 214.213.44.22
>   gateway 214.213.44.21 (or .18 which is the Xen0 ip)
>   netmask 255.255.255.240
 
  Sorry to respond to my own posting, but I need to correct something:

 The above statements about using the gateway ip in the aliased
interface are plain wrong. You should not have any gateway for 
an alias. The alias forms a bridge-like struct with the primary nic.
Having a bridge inside of a bridge can confuse routing.

 What I did find is that many of the aliased interfaces would not
be reachable from the outside without first pinging out. I tried
a number of things but I finally turned on STP in the bridging
code. That seemed to help. Now all my aliased interfaces are 
reachable without any special provision.

-Phil Carinhas
--
.--------------------------------------------------------.
| Dr. Philip A. Carinhas       | pac(at)fortuitous.com   |
| Fortuitous Technologies Inc. | http://fortuitous.com   |
| Linux Networking & Security  | Tel : 1-512-351-7783    |
`--------------------------------------------------------'


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