Hello-
I recently configured a linux/routed router on my LAN to create a subnet. I
have spent the past 6 days solid trying to figure out why it isn't working
properly; in that time I have printed/studied over 130 pages worth of
documentation and e-mail archieves with no luck!
| A | B | C |
In the diagram above, A is the existing network (10.1.70.0), B is the router
(with IP address 10.1.70.105 on eth0 and 10.1.71.1 on eth1) and C is the new
subnet (10.1.71.0).
The problem I am having is that machines on network A can't ping machines on
network C, and machines on network C can't ping machines on network A.
However, B (the router) can ping both machines on network C and A. The
really strange thing is that the Win32 clients on both networks A and C can
see one-another (but they can't ping one-another) in Network Neighborhood
(WINS is not yet configured).
I have included a 'clearer' map of my network topography below (I tried to
make it clear that the newly added router comes off of the second 3COM hub,
thus the need for the router in the first place before the Bay Networks
hub).
Internet
|
|
Main Cisco Router (10.1.70.1)
|
|
3COM Hub (10.1.70.0)
| | |
| | |
| | 3COM Hub (10.1.70.0)
| |
| 3COM Hub (10.1.70.0)
|
3COM Hub (10.1.70.0)
|
|
Linux/Routed Router (10.1.70.105 / 10.1.71.1)
|
|
Bay Networks Hub (10.1.71.0)
The router that I added is running Linux 2.0.36 (RedHat 5.2, yes I know it's
old hehe). IP forwarding is enabled (cat /proc/sys/net/ipv4/ip_forward
brings back a "1"). I failed to mention above that the router can access the
Internet fine through the gateway, 10.1.70.1. However, none of the machines
placed on the new subnet can access the Internet (since the gateway is on
the other side of the router... probably obvious but I thought I would
mention that anyway). The new gateway addresses have been added to all of
the client machines as needed.
Perhaps there is something wrong with my routing table? I have included it
below just in case (sorry this is getting so long!).
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
10.1.70.0 0.0.0.0 255.255.255.0 U 0 0 38 eth0
10.1.71.0 0.0.0.0 255.255.255.0 U 0 0 7 eth1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 3 lo
0.0.0.0 10.1.70.1 0.0.0.0 UG 0 0 1 eth0
lo Link encap:Local Loopback
inet addr:127.0.0.1 Bcast:127.255.255.255 Mask:255.0.0.0
UP BROADCAST LOOPBACK RUNNING MTU:3584 Metric:1
RX packets:5551 errors:0 dropped:0 overruns:0 frame:0
TX packets:5551 errors:0 dropped:0 overruns:0 carrier:0
collisions:0
eth0 Link encap:Ethernet HWaddr 00:00:1B:4C:9C:84
inet addr:10.1.70.105 Bcast:10.1.70.255 Mask:255.255.255.0
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:128911 errors:0 dropped:0 overruns:0 frame:6
TX packets:4382 errors:0 dropped:0 overruns:0 carrier:0
collisions:0
Interrupt:5 Base address:0x340
eth1 Link encap:Ethernet HWaddr 00:00:1B:4C:8B:E3
inet addr:10.1.71.1 Bcast:10.1.71.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1393 errors:0 dropped:0 overruns:0 frame:0
TX packets:3175 errors:0 dropped:0 overruns:0 carrier:0
collisions:0
Interrupt:9 Base address:0x320
I don't want the router to do any sort of masquerading/firewalling etc...
security/IP address conservation is not an issue here. 'routed' is what I
have running for this (yes, it is running :) ).
I'm not sure if the main Cisco router was configured as having a netmask of
255.255.254.0 or 255.255.255.0 as that is out of my hands. I have tried both
configurations on the router and clients... the linux/routed box I'm working
on won't allow 10.1.71.0 with netmask 255.255.254.0 (though it will allow
10.1.70.0 netmask 255.255.254.0, I don't get that one either) so that has
been another problem. I am guessing the main Cisco router has 255.255.254.0
as the netmask... could that be a problem, or does it even matter? Though
there are something like 100 machines on the network here, only a handful
(25 at most) are used or even turned on simultaneously at any given time,
so network traffic really isn't a concern at this point.
I can't think of anything else...
Any suggesions or ideas would be *much* appreciated!
Paul Levitz
http://www.hbcsd.k12.ca.us/peterson/technology
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