Ip aliasing

From: Psarras Nikos <psarnik_at_it.teithe.gr>
Date: Thu, 09 Sep 1999 16:33:26 +0300

  salut,

We are using Alpha 3000/400 running du 40e and patch kit 2 installed.

We tried to use a second ip address on the same interface (ln0). The
second ip is on a different subnet with different subnet mask.
So we did :
  
  ifconfig ln0 alias x.x.x.x netmask 255.255.255.0

The primary address is y.y.y.y netmask 255.255.255.240

Using netstat -nia gives the next:

Name Mtu Network Address Ipkts Ierrs Opkts
Oerrs Coll
ln0 1500 <Link> 08:00:2b:33:5e:a9 11080 0 9941
0 6
ln0 1500 DLI none 11080 0 9941
0 6
ln0 1500 yyy.yy.yyy.32/28 yyy.yy.yyy.yy 11080 0 9941
0 6
                             224.0.0.1
ln0 1500 xxx.xx.xxx/24 xxx.xx.xxx.xx 11080 0 9941
0 6
                             01:00:5e:00:00:01
                             cf:00:00:00:00:00
sl0* 296 <Link> 0 0 0
0 0
lo0 4096 <Link> 619 0 619
0 0
lo0 4096 127/8 127.0.0.1 619 0 619
0 0
                             224.0.0.1
                             01:00:5e:00:00:01

Seems ok.

The problems:

1) Using traceroute
# traceroute -s xxx.xx.xxx.xxx www.whatever.com
traceroute: Incorrect source address xxx.xx.xxx.xxx

2) At our HP Openview Managment station an error starts to appeare stating
that the alpha machine has inconsistent subnet mask of */28 on interface
ln where it should be */24
By viewing the information produced about the object which relates to the
alliased ln interface we see that the subnet mask reported is */28.

Searching through the list archives we found some similar situtations but
none of them had a different ip subnet using different mask on the same
interface.

Any suggestions?

take care
salaGatoR
Received on Thu Sep 09 1999 - 13:35:51 NZST

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