Joe Taylor wrote:
My earlier problem with dropped multicast packets seems to be fixed in
MAP65 v0.8. However, when running the Linrad-MAP65 combination on two
separate computers I still have some network-related problems.
Perhaps someone on this list who knows much more than I about
networking can help.
My computer network looks like this:
ADSL 10 Mb/s --> Computer_A
DSL --> Modem --> Ethernet --> Computer_B
Hub |
--> Computer_C
Three computers are connected to a 10 Mb/s Ethernet Hub.
Have you considered replacing the hub with a 100 Mbps full-duplex
Ethernet switch? There are many advantages in this over a hub.
Computer_A is my XYL's machine. Computer_B runs Windows 2000 Pro, and
Computer_C runs Linux (presently the Kubuntu 6.06 distribution). In
addition to the connections of all three machines to the hub, a
crossover cable makes a direct 100 Mb/s connection between computers B
and C.
The ethernet interfaces on B and C appear to be configured correctly.
On Linux they appear as eth0 and eth1 (occasionally they boot up as
eth0 and eth2, I don't know why???).
This is configurable, generally, and should be fixed if you intend to
use interface based static routes. Check here for more info on iftab
(/etc/iftab):
http://linux.die.net/man/5/iftab
Connections to the Hub are assigned dynamic IP addresses;
I assume these addresses are in the 192.168.1.x range?
I assigned hard-coded addresses 192.168.10.12 and 192.168.10.13 for
the direct inter-machine connection
between B and C.
I can use the 100 Mb/s direct line for many purposes. I can ping over
it in either direction; I can ssh into Linux from Windows; I can use
Cygwin/X (as described above) to display Linux X programs on the
Windows screen.
However, I cannot seem to persuade Windows 2000 Pro to accept
multicast packets over the direct line. When I run Linrad on computer
C and MAP65 on B, the multicast traffic is always received over the
slow line, through the Hub. This uses most of the 10 Mb/s link's
bandwidth, and my wife can't read her email when I'm on the air. This
is NOT GOOD.
An Ethernet switch would eliminate this, as traffic passing between two
machines (B-C) does not use any bandwidth, nor is it seen, by any other
machines. Internet access by machine A would be unaffected by a transfer
occurring between machines B and C. Machine A would not see the traffic,
nor would there be any contention for bandwidth on it's connection
because of the B-C traffic.
By default the multicast traffic generated by Computer_C goes to
eth0. I can use the Linux "route" command to explicitly tell the
system to use eth0:
# route add -net 224.0.0.0 netmask 224.0.0.0 dev eth0
This works fine (but of course, still sends the heavy multicast
traffic through the hub). If I remove this routing instruction and
instead enter
# route add -net 224.0.0.0 netmask 224.0.0.0 dev eth1
the multicast data are not received by MAP65 running on the other
machine.
If I unplug the crossover cable from the Windows machine and instead
plug it into a laptop running Win/XP, the laptop receives the
multicast packets without a problem.
Thus, it would seem that the problem must be in my setup of the Win2k
machine -- the one with two ethernet interfaces. Can anyone shed any
light on this situation for me?
Would there be sufficient bandwidth in a 100baseTx connection (100 Mbps
full-duplex) to handle both of the networking streams, i.e. the hub and
the direct stream? If so, replacing the inefficient hub with a faster
switch, thus confining network traffic to only the ports of the involved
machines, might solve the issue. This might allow you to eliminate the
direct connection between machines B and C.
As to W2k the unicast and multicast routes are handled in separate
tables, check here for more info:
http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/intwork/inaf_mul_hwmc.mspx?mfr=true
Hope some of this is of some use :)
Rick Kunath, k9ao
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