[Info-vax] Routing when using two interfaces/networks.

[Bart.Zorn@gmail.com]

On Jan 17, 3:28 pm, Jan-Erik Soderholm <jan-erik.soderh... at telia.com>
wrote:
> Hi.
> We have some hard-to-identify network problems at
> a site and I'm now thinking that it might have something
> to do with how the routing is setup in the VMS system.
>
> The VMS system (the "prod" system) has two interfaces :
>
> $ tcpip sh inter
>
> Interface   IP_Addr         Network mask
>
>   LO0        127.0.0.1       255.0.0.0
>   WE0        193.183.98.2    255.255.255.0
>   WE1        10.32.137.1     255.255.255.0
>
> The 193.183.x.x is the "old" network that will be removed
> anytime(tm). The 10.32.x.x network is where most of the other
> stuff (term-servers, PC-clients and so on) are. Note that
> most other equipment on 10.32.x.x are on other subnets then
> 10.32.137.x. The only other host on the 10.32.137.x are mainly
> the other VMS systems. All "user" equipment are on other
> 10.32.x.x networks.
>
> The current routing looks like this :
>
> $ tcpip sh route
>
>                         DYNAMIC
>
> Type           Destination                    Gateway
>
> AN    0.0.0.0                         193.183.98.251
> AN    10.32.137.0/24                  10.32.137.1
> AH    10.32.137.1                     10.32.137.1
> AH    127.0.0.1                       127.0.0.1
> AN    193.183.98.0/24                 193.183.98.2
> AH    193.183.98.2                    193.183.98.2
> st
> $ tcpip sh route/perm
>
>                         PERMANENT
>
> Type           Destination                    Gateway
>
> PN    0.0.0.0                         193.183.98.251
>
> The "dev" system has only one interface and looks like this :
>
> $ tcpip sho inter
>
> Interface   IP_Addr         Network mask
>
>   LO0        127.0.0.1       255.0.0.0
>   WE1        10.32.137.3     255.255.255.0
>
> $ tcpip sh rout
>
>                               DYNAMIC
>
> Type           Destination                   Gateway
>
> AN    0.0.0.0                          10.32.137.254
> AN    10.32.137.0/24                   10.32.137.3
> AH    10.32.137.3                      10.32.137.3
> AH    127.0.0.1                        127.0.0.1
>
> $ tcpip sh rout/perm
>
>                               PERMANENT
>
> Type           Destination                   Gateway
>
> PN    0.0.0.0                          10.32.137.254
>
> The "problems" we are seeing are e.g. :
>
> - Troubles ("hangs") when FTP copying from "prod" to "dev".
> - Intermittent slow access from PC clients.
>
> My guess is that the disturbances are due to the fact that all
> routing goes through the 193.183.98.251 gateway, even between
> different 10.32.x.x subnets, right ? And that the solution
> probably would be to simply move the default router from
> the 193.183.98.251 gateway to the 10.32.137.254 gateway on
> the system with two networks ?
>
> Jan-Erik.

Two questions here:

- Does your production systems depend heavily on TCP/IP connections
(most likely yes) and on which subnet do most of the clients reside?
- Is the 10.32.x.x network subdivided with routers or is it a single
network like 10.32.0.0/16?

If you have problems in the current setup with traffic between prod
and dev, you might have similar problems between prod and it's clients
when you change the default routing.

Bart Zorn