topic Re: UCX alias on interface in Operating System - OpenVMS

UCX alias on interface

Wim Van den Wyngaert — Tue, 08 May 2007 03:01:23 GMT

I defined an alias as
ifconfig WE0 -alias wim

But when I use the node A (on which this alias was added) to go to node B via RLOGIN I find that the source IP address (in ucx show dev) is WIM instead of A.

I now tried
ifconfig WE0 -alias wim metric 1
and now it is working as expected (that is source is now A).

1. Is this a correct solution or are there still pitfalls ?

2. How can I see the metric of all aliases ?

Wim

Re: UCX alias on interface

Steve-Thompson — Tue, 08 May 2007 07:53:16 GMT

Hi Wim

I tried this from a VMS732/tcpip5.4 box onto a slightly older VMS box 722/tcpip5.1

ifconfig we0 alias wim netmask 255.etc

ifconfig -a didnt show a metric here as it's ZERO.

I executed rsh B ucx sho dev, several times ....
The report on the other node ALWAYS gave me your A equivalent as an answer, I couldnt reproduce the "error".

Are you running RIP on your A box, it'll use the metric values...
I dont have RIP running, which "might" explain why I cant reproduce your results.

Your Q2. (just changed around a little)
I assume A and WIM are on the same net, so they should have the same metric. Ie WE0 has the metric, not the aliases....

I'll see if I can put RIP on one of my boxes!
An interesting question!

Steven

Re: UCX alias on interface

Wim Van den Wyngaert — Tue, 08 May 2007 09:00:37 GMT

I don't have RIP. And indeed the metric is placed on WE0 (shown by ifconfig -a).

Still wonder why WIM comes up when no metric is used.

May be I could play with a smaller packet size (hoping IP would prefer the 1500 one).

The problem is that I must be able to move the alias without stopping anything except the application that is using it.

Wim

Re: UCX alias on interface

Steve-Thompson — Tue, 08 May 2007 09:25:18 GMT

Wim

I've duplicated your steps and included the output .... see if it helps!
I've added some other stuff just in case.

I still cant duplicate your conditions!

Steven

Re: UCX alias on interface

Wim Van den Wyngaert — Tue, 08 May 2007 09:26:40 GMT

Post again with .txt !

Wim

Re: UCX alias on interface

Wim Van den Wyngaert — Tue, 08 May 2007 10:08:05 GMT

Further tests : the alias is only used when the traffic passes thru a router. I think.
And even with metric 1.

Re: UCX alias on interface

Steve-Thompson — Tue, 08 May 2007 10:21:54 GMT

Sorry about the file name.....

following your articles... (I assume) the two nodes in your thread are on different nets, no?

My tests were with 2 nodes on the same net.

Re: UCX alias on interface

Wim Van den Wyngaert — Tue, 08 May 2007 10:49:50 GMT

Yes they were on different nets.

In the mean time I've read that the last added alias is used.

Re: UCX alias on interface

Wim Van den Wyngaert — Wed, 09 May 2007 02:14:33 GMT

Got it.

If you use the option 'netmask 255.255.255.255' when doing ifconfig then the alias is no longer used.

I checked what changed with ifconfig -a but this command display the wrong network mask (that of the interface).

Then I checked what changed with ucx sho rout and found without netmask a route was added for 128.231.0.0/30 going thru WIM while with the netmask it was for 128.231.158.102/32 (the address of WIM). The mask of the interface is 255.255.240.0.

So, WIM will only be used as a source when going to WIM (tested and found true). In all other cases the 'normal' interface is used.

So, now it can be assigned to an application. When the application goes down, the alias is unused.

Wim

Re: UCX alias on interface

Steve-Thompson — Wed, 09 May 2007 05:43:57 GMT

Hi Wim

Good news!
Yes, ifconfig has the default behaviour of putting in a standard mask for the net in use.
When I did my tests, I added my correct netmask of 255.255.255.0, to the ifconfig alias command.
If I hadn't, ifconfig would give me an 8 bit mask, which I didnt want to do. :-)

Forgive me for only writing "255.etc"

Regards
Steven