Greg Wilson-Lindberg wrote:
At this point I'm just asking for a direction to go to get the
information that I need. While I've been writing low level networking
software for many years, I've never had to get into routing.
Here's my problem, we have an environment where we have a machine with
one ethernet connection to the wider network and a number of HDLC cards
that connect to other embedded systems that we NAT out to the ethernet WAN.
------------------------------
| (172.16.4.9/12) hdlc2|---------\
| | |
WAN 10.0.0.0/8 ----| eth0 (10.1.32.x/8) | |
| | |
| (172.16.4.9/12) hdlc1|------\ |
| | | |
| (172.16.4.9/12) hdlc0|---\ | |
------------------------------ | | |
| | |
| | |
machine1a-------------------| | |
(172.24.127.249) | | |
(172.16.129.9) | | |
| | |
machine2a-------------------| | |
(172.24.0.37) | | |
(172.16.129.17) | | |
| | |
machine3a-------------------| | |
(172.24.0.41) | | |
(172.16.129.25) ... | |
| |
machine1b----------------------| |
(172.24.127.250) | |
(172.16.129.9) | |
| |
machine2b----------------------| |
(172.24.0.38) | |
(172.16.129.18) | |
| |
machine3b----------------------| |
(172.24.0.42) | |
(172.16.129.26) ... |
|
machine1c-------------------------|
(172.24.127.251) |
(172.16.129.11) |
|
machine2c-------------------------|
(172.24.0.39) |
(172.16.129.19) |
|
machine3c-------------------------|
(172.24.0.43) |
(172.16.129.27) |
...
As can be seen from the above diagram, the addresses on the HDLC
channels are not on separate subnets. We also have some broadcast
addresses that the machines on the HDLC nets will need to receive. We
do know all of the addresses for all of the machines on the HDLC nets,
but we could end up with as many as 30-50 on each net. Most of the
packets coming from the ethernet WAN will go to just one of the HDLC
nets, but the broadcast packets will need to go to all of them. Also,
the HDLC nets do not need to be able to communicate between themselves.
Can anybody at least point me in the proper direction on how I need to
attack this problem?
Is there a specific reason you cannot further subnet the 10.0.0.0/8 network for
your HDLC channels and eschew the NAT? Then at least ignoring the issue of
"routing" broadcast datagrams (these are IP broadcasts and not simply ethernet
broadcasts right?) reaching-out and touching the HDLC devices from the WAN would
seem to be more straightforward.
rick jones
visions of many static routing table entries floating through his head
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