richier@imag.imag.fr (Jean-Luc Richier) (06/06/88)
I have a problem with the 4.3 version of TCP-IP, when I use both gateways and
multiple nets on one ethernet.
Description:
I have a ethernet LAN which contains 2 IP networks (In fact, it consists of
two ethernet networks, interconnected with Level 2 Bridges).
There is also a gateway on the LAN, which provides acess to a third network.
The structure is as follows (with arbitrary IP numbers):
etherLAN IP-net-A(192.0.0.xx) IP-net-B(192.0.1.yy)
--------------------------+---------------------------------
| Gateway (addr 192.0.0.1, dstaddr 192.0.2.1)
|
| Gateway (addr 192.0.2.2, dstaddr 192.0.0.2)
--------------------------+---------------------------------
etherLAN IP-net-C(192.0.2.xx)
The machines on IP-net-A use the route commands:
route add network IP-net-B <name of the machine> 0
route add network IP-net-C 192.0.0.1 1
The machines on IP-net-B use the route command:
route add network IP-net-A <name of the machine> 0
The problem is that I cannot access the net IP-net-C from machines on
the net IP-net-B: The route command
route add network IP-net-C 192.0.0.1 1
is refused, with the message "network is unreachable"
I have been unable to solve this problem with route, routed, or even by
using the "arp -s" command (trying to use proxy arp).
About 6 months ago, some persons in netland (in comp.protocols.tcp-ip)
suggested the idea of declaring more than one ethernet interface, in
order to solve the problem of more than one net on a LAN, each with
subnet and non standard broadcast addresses. I have been unable
to implement this solution (on Vax or Sun, these interfaces do not
configure, and therefore ifconfig does not work).
Is there any solution? I can think of many, but they all ask for modifications
in the kernel source. I hope that there is simpler solutions.
------------
Jean-Luc Richier
richier@imag.imag.fr or richier@imag.UUCP or uunet.uu.net!imag!richiercpw%sneezy@LANL.GOV (C. Philip Wood) (06/30/88)
Get rid of the Level 2 Bridge(s). Put IP routers in their place. Don't have two networks on the same LAN. I define LAN as a network of hosts all sharing the same network address. phil wood (cpw@lanl.gov)
slevy@UC.MSC.UMN.EDU ("Stuart Levy") (07/01/88)
You should be able to handle reaching a gateway, on the same wire as you but on a different (sub)network number, using the following awful kludge: Allocate a fake IP address on your own (sub)net for the remote gateway. On the local machine: arp -s fake-gw-address gateway-Ether-address perm On the local machine: route add destination-net fake-gw-address 1 and hope the "permanent" arp is never purged from the cache.
richier@imag.UUCP (Jean-Luc Richier) (07/01/88)
In your mail "Re: gateways and more-than-one-IP-net on one ethernet" dated 30 Jun, you say : /* * * Get rid of the Level 2 Bridge(s). Put IP routers in their place. * Don't have two networks on the same LAN. I define LAN as a network * of hosts all sharing the same network address. * * phil wood (cpw@lanl.gov) * */ I agree with. I do not like this construction. However I a not the administrator of this structure, and I have to live with it. I cannot modify the basic concept: 2 LAN linked by a level bridge (When I look to "classical" networks in France, I must be grateful to have at least a TCP/IP LAN, and not the "good" solutions such as DECNET or SNA) Therefore I must survive, and all I can obtain is to put software on some of the machines of the LAN. A good solution would be a a kernel patch to allow adding routes in the kernel according interface and not proxy-arp deaIP addresses, or a proxy arp daemon, to fake route protocols Do you know of such solution. I know that somebody (Barry Shein at Boston University) has written a proxy arp deamon for sun, but I have been unable to contact him. Do you have seen any such software on some site?? Thank Richier richeir@imag.UUCP richier@imag.fr --
hedrick@aramis.rutgers.edu (Charles Hedrick) (07/02/88)
route add NETWORK YOURADDRESS 0 where NETWORK is an additional network on the same Ethernet and YOURADDRESS is the address of your machine's interface on that Ethernet. This declares the additional network as being directly connected.