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PING issue while enabling multiple IP interfaces

 
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O. Jadot
Occasional Advisor

PING issue while enabling multiple IP interfaces

Hello all.

Here's an issue I encounter with IP addressing :

I have two AlphaServer 1200 running VMS8.2 as a cluster with TCPIP V5.5 installed.

Each of these has two ethernet interfaces, ewa0 and ewa1.

The first interface is connected to a VLAN and the second to another one, VLANs cannot reach each other.

I defined an IP address for the first interface of each servers ; 10.2.1.158 for one and 10.2.1.159 for the other. Netmasks are 255.255.255.0 everywhere.

The gateway has been defined to be 10.2.1.230. BIND server is 10.2.1.150. Both of these addresses respond to ping requests from my servers.

Everything seems to work allright.

Problems occurs when I set an IP address to the second interface of each servers, so they can be reached from the other VLAN.

As I set 10.2.1.160 on one and 10.2.1.161 on the other, ping requests on my servers fail half the time. Ping requested from my servers on other computers fail the same way.

I think of a routing issue, but cannot find the point.

Thanks by advance for your help,

O.Jadot
6 REPLIES
Wim Van den Wyngaert
Honored Contributor
Solution

Re: PING issue while enabling multiple IP interfaces

Since this is another VLAN/network, the network part of the IP address must be different. Not 10.2.1. but e.g. 10.2.2.

Otherwise IP will think that you only have 1 network and use any of the 2 cards for reaching it.

Wim
Wim
Ian Miller.
Honored Contributor

Re: PING issue while enabling multiple IP interfaces

If you use the -I option with ping to specify the interface does it help?
____________________
Purely Personal Opinion
Lokesh_2
Esteemed Contributor

Re: PING issue while enabling multiple IP interfaces

You can use traceroute also to find out how the path packet is taking. Try also the "-s" option of traceroute to start traceroute from a specific source address.

HTH,
Thanks & regards,
Lokesh
What would you do with your life if you knew you could not fail?
Jan van den Ende
Honored Contributor

Re: PING issue while enabling multiple IP interfaces

Jadot,

Sorry, my expertise in things IP is inferior to many other in this forum, but

WELCOME to the VMS forum!

Proost.

Have one on me.

jpe
Don't rust yours pelled jacker to fine doll missed aches.
Dirk Bogaerts
Frequent Advisor

Re: PING issue while enabling multiple IP interfaces

You should put the 2nd interface of each server in a different subnet; otherwise you might have routing problems, I was told once.

regards,
O. Jadot
Occasional Advisor

Re: PING issue while enabling multiple IP interfaces

Thanks for your replys.

I have tested Wim van den Wyngaert's proposition, which was the good one. I now have a fully functional IP solution.

Thanks to you all for your help, and to Jan van den Ende for the welcome.

O.JADOT