[Udpcast] Problems with udpcast 20051223

Alain Knaff alain at knaff.lu
Wed Feb 8 23:01:26 CET 2006


John Newbigin wrote:
> First off I had a compile error:
> console.c:36: parse error before `*'
> 
> console_t needs to be defined at the start of prepareConsole.  Easy fixed.

Oops, indeed. There was a variable declaration after code, which current
gcc compilers tolerate just fine (but old compilers will choke on it)

> 
> The real problem I am having is that multicast won't work with more than 
> one client.  When I run with only one client it runs OK.  If I have more 
> than one the sender prints out
> Timeout notAnswered=[1] notReady=[1] nrAns=1 nrRead=1 nrPart=2 avg=9198
> Timeout notAnswered=[1] notReady=[1] nrAns=1 nrRead=1 nrPart=2 avg=9198
> Timeout notAnswered=[1] notReady=[1] nrAns=1 nrRead=1 nrPart=2 avg=9198

Depending on the speed of your machines, it's quite normal that one
machine may lag slightly behind, which the sender signals.


> and none of the clients work.

This is more surprising. I just did a test here with 2 receivers (_before_
fixing the compilation error and the double connect message issue), and
everything worked just fine.

Are you sure your network interfaces are set up correctly? (For a single
receiver, udpcast uses unicast, but for multiple receivers it uses
broadcast or multicast, so if for whatever reason broadcast and/or
multicast does not work on your net, there may be problems). One
possible problem area could be if the net is configured for a different
broadcast address on the sender than on the receiver(s). Do an ifconfig
to check this out:


> ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:04:61:45:6B:1C
           inet addr:192.168.1.10  Bcast:192.168.1.255  Mask:255.255.255.0
                                         ^^^^^^^^^^^^^
                                               |
  [This address should be the same for all machines on your network]

           inet6 addr: fe80::204:61ff:fe45:6b1c/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:389 errors:0 dropped:0 overruns:0 frame:0
           TX packets:449 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:131658 (128.5 Kb)  TX bytes:182962 (178.6 Kb)
           Interrupt:12 Base address:0xe400




Try doing a tcpdump while doing both tests.

Also, make sure that you see (on the sender) connect messages for both
receivers:

New connection from 192.168.1.3  (#0) 00000009
Ready. Press any key to start sending data.
New connection from 192.168.1.2  (#1) 00000009
Ready. Press any key to start sending data.

> I have also tested netcast (http://sourceforge.net/projects/netcast) 
> which works with multiple clients so I don't think it is a multicast 
> issue.  netcast does not have many features so I would like to use udpcast.
> 
> I have also got the message
> Unexpected opcode 0700
> and
> Unexpected opcode 0200
> a few times so I wonder if that is related to my problem.

Actually, it's not related. Udp-receiver was sending its connection
message twice, but the sender is able to deal with it (and just resends
its reply). At that point, the receiver no longer expects the reply, so
it just ignores it (... and displayes the message).

In any case, I've uploaded a new tar (udpcast-20060208.tar.gz) which
fixes both the compilation and the double connect message issue (but
as said: multiple receivers do also work without these fixes... so the
reason for your multiple receivers problem must lie somewhere else...)

> Any help would be greatly appreciated.
> 
> John.
> 
> 


Regards,

Alain



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