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

[Jan-Erik Soderholm]

Kari Uusimäki wrote:
> On 17.1.2010 16:28, Jan-Erik Soderholm 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.
>>
>>
>>
> 
> The default gateway should be the one which routes the most traffic. In 
> this case the gateway at 10.32.137.254.
> 
> Nothing prevents you from adding network entries for the different 
> 193.*.*.* subnets which all are reachable through the gateway at 
> 193.183.98.251.
> 
> Of course you can do supernetting like said in another post. Provided 
> that you don't have really old routers which don't understand supernetting.
>

Or beeing such a realy old sys manager that doesn't understand
supernetting... :-)

Anyway, the plan is to simply switch all routing to the "new"
network and just let the "old" network die...

Jan-Erik.


> 
> Kari
>