SUMMARY: default routes

From: Larry Chin (larry@cch.com)
Date: Wed Oct 14 1992 - 01:20:20 CDT


============================ Original Query ==================================

I have just recently gotten an 19.2K connection to the Internet, and already
my headaches have started ( happens every time I have something new to do ).
I am very new to this Internet stuff so please forgive the questions if they
seem particularly dumb.

I have a machine, cchtor, that is connected to the 19.2K line. This machine
has the point to point addresses that connect it to uunet. cchtor is also
on the 192.139.241.xx net. On this same net is sunset, which acts as a router
to the 192.139.242.xxx net.

the default route on cchtor points at uunet and I can ping other machines such
as the archie server at rutgers.

Now the question is how do I configure the routing tables on sunset to know
that the default route to the world is to be through cchtor ? basically I
want sunset to be able to access the outside world as well. I have tried

route add default cchtor 1
route add default uunet 1

neither of which works. the first one seem to allow the traffic to travel from
sunset out, but there does not seem to be a way back again.

Furthermore what route would I use for a machine on the 192.139.242.xxx net to
be able to access a machine at another site ?

net configuration:

       uunet 142.77.1.201
        /
       /
      /
     cchtor------------------------sunset------------------192.139.242.xxx net
192.139.241.2 192.139.241.1
                                     +
                                192.139.242.1
                                

Routing table from cchtor: ( 192.139.241.2 )
==========================
Destination Gateway Flags Refcnt Use Interface
127.0.0.1 127.0.0.1 UH 1 43 lo0
default 142.77.1.201 UG 1 14 pp0
142.77.1.201 142.77.253.12 UH 0 0 pp0
192.139.241.0 192.139.241.2 U 42 16519 le0
192.139.242.0 192.139.241.1 UG 3 16528 le0

Routing table from sunset: ( 192.139.241.1 )
=========================
127.0.0.1 127.0.0.1 UH 1 76 lo0
default 192.139.241.2 UG 0 21 le0
192.139.241.0 192.139.241.1 U 46 4395010 le0
192.139.242.0 192.139.242.1 U 7 509381 le1

I shure hope someone out there can help me on this.
any and all help would be appreciated.

===============================================================================

Well as usual the list comes through with flying colors.

Some of you had suggested that the UUNET side of things had not been configured
properly, and that seems like the case. I had got things working by using a
hop count of 2 ( route add default cchtor 2 ), but of course that did not
make too much sense. Now however, things seem to be working properly since
"route add default cchtor 1" allows traffic out and back again.

Thanks to all of you who took the time to reply.

Eckhard.Rueggeberg@ts.go.dlr.de
sjl@doc.ic.ac.uk
Peter.Timofejew@sciex.com
Gary Blumenstein <garyb@gcm.com>
steve@avalon.dartmouth.edu (Steve Campbell)
Ted Nolan SRI Ft Bragg <ted@usasoc.soc.mil>
jkays@msc.edu
algold@server01.lncc.br (Alexandre Leib Grojsgold)
Phil Green <pgreen@aoc.nrao.edu>
baumann@proton.llumc.edu (Michael Baumann)
grs@claircom.com (Gregg Siegfried)
guyj@uunet.ca (Guy Jones)
Barry Margolin <barmar@Think.COM>

Special Thanks to Jeff Kays<jkays@msc.edu> who went into detail in his reply,
and which detail was a great help.

Larry Chin {larry@cch.com} CCH Canadian Ltd.
System Administrator 6 Garamond Court
Research and Development Don Mills, Ontario.
(416) 441-4001 ext. 349 M3C 1Z5

Eggnog is a traditional holiday drink invented by the English. Many
people wonder where the word "eggnog" comes from. The first syllable
comes from the English word "egg", meaning "egg". I don't know where
the "nog" comes from.

To make eggnog, you'll need rum, whiskey, wine gin and, if they are in
season, eggs...

===============================================================================
===============================================================================

On the machines on the 192.139.242.xxx net it's easy :
        /usr/etc/route add net default sunset242 3
where sunset242 is the name sunset has in the 242 net.
On sunset itself it ought to be
        /usr/etc/route add net default cchtor 0

I don't know exactly what these numbers mean, but we have a situation
vaguely similar to yours, and that is how it works.

Eckhard R"uggeberg
eckhard@ts.go.dlr.de

===============================================================================

On sunset run routed (or preferably gated - available from many archives)

On the 192.139.242.xxx hosts have a default route pointing at sunset.

you also need to run routed/gated on cchtor.

gated is great because it allows to to do all sorts of interesting security
things - like `believing' routes from certain hosts and not from others.

===============================================================================

    We hooked up through UUNET Canada as well (around the beginning of
August). We have exactly the same problem. I've mentioned it to UUNET,
but I've been too busy to follow it up. Personally, I think the problem is
with the SLIP driver that they supplied us with (which is probably the same
one you have). I have a copy of 'Managing TCP/IP' by O'Riley & Associates,
and they have an example of how to configure a SunOS machine for a
point-to-point connection, including all of the routing. It is very
straight forward. Well, I did the routing as per the example (including
variations), and no luck (same thing too... I can get it so that packets
can go out, but they seem to dissapear into the void). When I get time,
I'm going to try the SLIP package that the example in the book was based
on.

        Peter

===============================================================================

On sunset, try: route add 142.77.1.201 192.139.241.2 0
The concept is that sunset already has a route to cchtor, but now needs a
route to uunet using cchtor as the gateway. I don't think you want to
use a default route (as you mentioned above). Please let me know if this
works.

===============================================================================

It sounds like perhaps the uunet machine has a route only to your host
cchtor and not to your entire network. So though packets from any of the
machines on your netowkr can get out, only packets to cchtor can get back.
You could verify this by having uunet check the route they have to your
host or network.

If this is the problem, you might solve it by having uunet explicitly
announce a route to your net, not just your host.

You did not mention what routing daemon you run on cchtor. I recommend you
run gated(8) rather than routed(8). You can obtain the current version of
gated(8) from gated.cornell.edu in directory pub/gated.

===============================================================================

I think you need to tell uunet that it can get to the 192.139.241 net
through cchtor, unless you are running some sort of routing protocol,
it will only know the point to point address of cchtor and not the other net

===============================================================================

Larry - Hi. It looks like your routing tables are pretty close. Let me
see if this will help.

Assuming your 192.139.242 network has no other route out besides sunset,
all you need on those hosts is:

route add default 192.139.242.1 1

This tells these hosts that any packet that is not destined for the
local 192.139.242 subnet should go to sunset. They assume that sunset
will know what to do with these packets.

In addition, I would recommend turning off in.routed, since it's not
needed and just creates a lot of unnecessary network traffic. Actually,
I don't see any reason, with the configuration shown, why you need
in.routed running on any of the hosts or routers.

The route table on these hosts should look similar to:

127.0.0.1 127.0.0.1 UH XX XX lo0
192.139.242.0 192.139.242.X U XX XX le0 (X is host num)
default 192.139.242.1 UG XX XX le0

On sunset, you will have routes for the 192.139.241 and 192.139.242 nets,
and a default route for all other packets to 192.139.241.2. You will need
a command like:

route add default 192.139.241.2 1

and the route table should look like:

127.0.0.1 127.0.0.1 UH XX XX lo0
192.139.241.0 192.139.241.1 U XX XX le0
192.139.242.0 192.139.242.1 U XX XX le1
default 192.139.241.2 UG XX XX le0

which is what you currently show. That should be right.

Finally, on cchtor, you need a route to get to the 192.139.242 net, and
a default route for everything else:

route add net 192.139.242.0 192.139.241.1 1
route add default 142.77.1.201 1

The routing table for cchtor should look like:

127.0.0.1 127.0.0.1 UH XX XX lo0
192.139.241.0 192.139.241.2 U XX XX le0
192.139.242.0 192.139.241.1 UG XX XX le0
default 142.77.1.201 UG XX XX pp0

I'm not an expert with serial links, but I would think you need a route
to the 142.77 network, which should be configured when you bring up the
pp0 link. I don't know the address of cchtor's serial interface, but if
it was 142.77.1.2, something like the following might be right:

142.77.0.0 142.77.1.2 U XX XX pp0

That assumes the 142.77.1 network is not a sub-network. If it is, we
can work on that.

I'm not sure if I understand the following line from cctor's routing table:

> 142.77.1.201 142.77.253.12 UH 0 0 pp0

What is 142.77.253.12?

Well, I hope this helps! Let me know if you have any questions on any
of this. It get's pretty wild once you start adding a few networks and
routers, but that's what makes this so much fun!!! :-) Good luck!

==============================================================================

It seems that your problem is related with the routing FROM 142.77.1.201
INTO your networks. How does 142.77.1.201 knows about 192.139.242.0?

If that does not help you too much, please send me the output of a
ifconfig -a both in sunset and cchtor. and tell me also if you are
running any routing daemon, like routed or gated. If you are not, let
me advise you to use gated. I can help you with that, if you want.

==============================================================================

Your routing table for both looks okay to me. Things to
check are

make sure your broadcast address on the 192 nets is correct
and you subnet mask. The next thing to check is that uunet
knows about the 192.139.242 net. If they don't know about the
net then you will get no return packets.

================================================================================

>
>I have a machine, cchtor, that is connected to the 19.2K line. This machine
>has the point to point addresses that connect it to uunet. cchtor is also
>on the 192.139.241.xx net. On this same net is sunset, which acts as a router
>to the 192.139.242.xxx net.
>
I assume (dangerous word) that you are running some kind of point-to-point
protcol (eg PPP) via an async 19.2Kb link? If so, routed is no help. Have you
looked at gated which supports PPP as well as RIP? you could then run
routed on sunset, with gated broadcasting the RIP packets.

>
>Now the question is how do I configure the routing tables on sunset to know
>that the default route to the world is to be through cchtor ? basically I
>want sunset to be able to access the outside world as well. I have tried
>
>route add default cchtor 1
>route add default uunet 1
Your problem here is that you have only specifed host addressing, not net
addressing.
try
route add net default cchtor 1
on sunset
>
>neither of which works. the first one seem to allow the traffic to travel from
>sunset out, but there does not seem to be a way back again.
This may be tied in with the PPP/routed problem again, remember that routing
is a two-way street, just because you can get out does not mean you can get in.
(I am assuming by the way that the 192.139.242.0 net is a valid,advertised,
sponsered net, else all bets are off. (poke, prod, yep it's valid, so thats
not the problem.)
>
>Furthermore what route would I use for a machine on the 192.139.242.xxx net to
>be able to access a machine at another site ?
the best way (short of running routed) is
route add net default sunset 1
this should cause sunset (as the default router for 192.139.242.0 to pitch
addresses to other nets to cchtor, which then pitches it to its default router,
which.... well, you get the picture

================================================================================

Larry, I am also new to this internet stuff, and I'd love to see your summary when you get some answers. This stuff perplexes me too.

One point I do have is this. Is the class C address set 192.139.242.XXX resistered as yours on the internet? If not, is it possible that traffic coming back off the internet is being resolved to sombody else's address?

Another point is that you may have to kill the routing daemon on sunsets and usea static routing table (you may be doing this already). Otherwise sunsets will build a routing table from data it gets from cchtor.

================================================================================

In article <9210052100.AA01330@cch.com> you write:
>Now the question is how do I configure the routing tables on sunset to know
>that the default route to the world is to be through cchtor ? basically I
>want sunset to be able to access the outside world as well. I have tried
>
>route add default cchtor 1
>route add default uunet 1
>
>neither of which works. the first one seem to allow the traffic to travel from
>sunset out, but there does not seem to be a way back again.

The first one looks correct to me. If the symptom is that the messages go
out but replies aren't coming back, then the problem is probably at UUNET.
Do they know that they should be sending traffic for the 192.139.242.XXX
network to cchtor? They need to do something equivalent to:

route add 192.139.242.0 cchtor 1

Or they may want you to run routed on cchtor, so that it will periodically
send them a list of all the networks it routes to. You should talk to the
support people at UUNET for precise instructions.

>Furthermore what route would I use for a machine on the 192.139.242.xxx net to
>be able to access a machine at another site ?

================================================================================



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