Phillip Helbig's recent question lead me to think while battling 18
wheel trucks on my bike.


Would it be possible to have VMS configured without a default route and
then listen for RIP information from routers to determine which router
provides a route to the rest of the world ? (I believe that TCPIP
Services provides the GateD service which does RIP). 

With the internet backbone now all BGP, is RIP still "state of the art"
for intranets, or is there an equivalent of BGP for intranets ?

The TCPIP configuration routine asks whether you want to provide a
default route manually or not. If you don't, you need a routing
protocol otherwise the system is locked inside its own IP network.
There are two kinds of routing protocols, interior like RIP (V1 and V2
which also supplies a mask IIRC) or OSPF and exterior protocols like
EGP (now obsolete) and BGP.
For an intranet the choice is between RIP and OSPF I guess. BGP is too
complex for a LAN. If the number of routers on your intranet is less
than 20 then RIP is your friend.

Hans

In article <42AE207F.F46917AA@teksavvy.com>, JF Mezei <jfmezei.spamnot@teksavvy.com> writes:
>Would it be possible to have VMS configured without a default route and
>then listen for RIP information from routers to determine which router
>provides a route to the rest of the world ? (I believe that TCPIP
>Services provides the GateD service which does RIP). 

Yes and yes (but not only RIP).

>With the internet backbone now all BGP, is RIP still "state of the art"
>for intranets, or is there an equivalent of BGP for intranets ?

My first choice would be OSPF.


BUT:

1) Usually, the network is driven by other folks than the systems.
And they usually don't want to share responsibility. So, running a routing
protocol on a host doesn't make the network people happy (eg. they can't
switch from RIP to OSPF on their own, the need the host people to change
the hosts IP config then, too)

2) As a host's manager, you don't want to rely totally on dynamic routing.
The network people might change their routing (information) protocol for
which you are eventually deaf (how many years is OSPF in routers and how
many years later GATED came to VMS?) and then you are w/o remote networks.
A catchall = default routing entry (in addition) would be a wise move.

3) If you define a default routing entry in the (VMS) host, then it is
important that you don't supply routing information to the other routers.
Otherwise you tell them that your VMS box _is_ the internet.
So, only listen, not supply.

4) Routers are vulnerable to (eg. redirect) attacks if not secured by
IP address filters and maybe secure key exchange. Iff the host is able
to share this functionality you still have the problem with the 2 groups.

So, yes, it is possible to use/run VMS/TCPIP with/as a IP router(s).
But it would be easier, if you only run it as a host with a default
routing entry and eventually a GATED listener (configured for the
protocol the routers you to exchange information)...

-- 
Peter "EPLAN" LANGSTOEGER
Network and OpenVMS system specialist
E-mail  peter@langstoeger.at
A-1030 VIENNA  AUSTRIA              I'm not a pessimist, I'm a realist

Peter 'EPLAN' LANGSTOEGER wrote:
> In article <42AE207F.F46917AA@teksavvy.com>, JF Mezei <jfmezei.spamnot@teksavvy.com> writes:
> 
>>Would it be possible to have VMS configured without a default route and
>>then listen for RIP information from routers to determine which router
>>provides a route to the rest of the world ? (I believe that TCPIP
>>Services provides the GateD service which does RIP). 
> 
> 
> Yes and yes (but not only RIP).
> 
> 
>>With the internet backbone now all BGP, is RIP still "state of the art"
>>for intranets, or is there an equivalent of BGP for intranets ?
> 
> 
> My first choice would be OSPF.
> 
> 
> BUT:
> 
> 1) Usually, the network is driven by other folks than the systems.
> And they usually don't want to share responsibility. So, running a routing
> protocol on a host doesn't make the network people happy (eg. they can't
> switch from RIP to OSPF on their own, the need the host people to change
> the hosts IP config then, too)
> 
> 2) As a host's manager, you don't want to rely totally on dynamic routing.
> The network people might change their routing (information) protocol for
> which you are eventually deaf (how many years is OSPF in routers and how
> many years later GATED came to VMS?) and then you are w/o remote networks.
> A catchall = default routing entry (in addition) would be a wise move.
> 
> 3) If you define a default routing entry in the (VMS) host, then it is
> important that you don't supply routing information to the other routers.
> Otherwise you tell them that your VMS box _is_ the internet.
> So, only listen, not supply.
> 
> 4) Routers are vulnerable to (eg. redirect) attacks if not secured by
> IP address filters and maybe secure key exchange. Iff the host is able
> to share this functionality you still have the problem with the 2 groups.
> 
> So, yes, it is possible to use/run VMS/TCPIP with/as a IP router(s).
> But it would be easier, if you only run it as a host with a default
> routing entry and eventually a GATED listener (configured for the
> protocol the routers you to exchange information)...

Actually, you can learn your default route dynamically without running a 
routing protocol.  Use the ICMP Router Discovery Protocol (called RDISC 
in TCPIP services).  This is an ICMP advertisement from the router that 
allows your host to learn about the presence of a router in essentially 
the same manner that DECnet and Appletalk do.  It is independent of the 
protocols used by the routers themselves to exchange routing information 
and the routers can be configured with a preference so that, if there 
are multiple paths out of your LAN, you can automatically fail over if 
the primary router fails.

This is only useful for a default route.  If you need to select a router 
based on your destination than either a static table or a dynmaic 
routing protocol is needed.  If there is only one router path out of 
your LAN, then you might as well just use a static default route 
(unless, for some reason, that one router has a tendency to change its 
address on the LAN).

Mark Berryman