carson@tron.UUCP (Dana Carson) (01/11/90)
Is it possible to have one system with one ethernet port on two
subnets? We have a class B network address divided up into subnets
(eight bits for subnet). We have a different subnet number from other
parts of the company in the area but due to the way the network is laid
out the ethernet is bridged so it's all one network. Can I use some
magic when I configure a system to make it talk to both subnets on the
same device so it can be the gateway between them?
--
Dana Carson
Westinghouse Electronic Systems Group Mail Stop 1615
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WIN: 285-3513mep@AQUA.WHOI.EDU (Michael E. Pare) (01/12/90)
I don't know what type of devices you have but I do that on one of our Proteon gateways. The two subnets are normally joined by two of these IP routers. The networks are also joined together by bridges for all other protocols. If one of the routers fails, I shut the IP filtering off on the bridges, and add the interface address of the broken gateway to the good gateway on the same ethernet interface. The bridges make the system look like one ethernet and the gateway handles the routing for the IP packets.
brf@zippy.Philips.Com (Bill Friday) (01/12/90)
I do not know of any way to configure one ethernet board to have to IP
addresses and be configured to route two subnets that exist on
the same wire ('ifconfig' does not permit that which define the
partameters asociated with the ethernet interface). There is something
you can try that is not very elegent but might work.
Assumptions about your net:
1 - class 'b' address with netmask 255.255.255.0
2 - subnet 130.140.80 and subnet 130.140.81 are connected with a
bridge and they need to communicate but have no route
Partial solution that might help:
1 - This will allow direct communication between node
130.140.80.10 and 130.140.81.10 that live on the logical
network.
2 - manually update the routing table on 130.140.81.10 with the
following:
'route add net 130.140.80 130.140.81.10 0'
3 - manually update the routing table on 130.140.80.10 with the
following:
'route add net 130.140.81 130.140.80.10 0'
The above command will establish a route between the two
specified hosts. Assume that the above nodes are sun
fileservers. If the diskless clients had a net mask of
255.255.0.0 nfs works fine between the two subnets. Oh yea, the
metric or hop count equal to zero means that the subnet is on
the same wire in the above route commands. By routing the net
through yoiurself it simple puts the packet on the wire. If
could be simplifies with route defalult to yourself if not
already used. You could include the manual route add in
your '/etc/rc.local'.
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