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multicast discovery fails

5 replies on 1 page. Most recent reply: Jul 26, 2002 3:09 AM by Fox Mulder

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marcus bl?mel

Posts: 3
Nickname: sanchofx1
Registered: Mar, 2002

multicast discovery fails Posted: Mar 6, 2002 7:08 AM
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Hello there,
i'm in some trouble with my (first) jini service. I have successfully implemented and run a simple "Hello World" service (using the 'Core Jini' Book from Keith Edwards) on my system. Everything works fine on a single compter. Now I trie to run the reggi service on an other maschine but the LookupDiscovery seems not to be able to find a Lookup service on an other maschine. The two systems participate in a LAN an have static IP-Adresses (192.168.1.1 and 192.168.1.3). The unicast discovery works fine, by the way.
So, what is wrong with my setup. Maybe I have to do som e special network setup??

Would appreciate some help very much..
Grettings,
Marcus Bl?mel


Bill Venners

Posts: 2284
Nickname: bv
Registered: Jan, 2002

Re: multicast discovery fails Posted: Mar 14, 2002 10:25 AM
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It is hard to say what your problem is. One problem that often crops up when people go from running everything on one machine to trying to get things going on multiple machines is that a localhost or 127.0.0.1 crept into their code somewhere. That doesn't sound like your problem, though.

Another thing that's possible is that sometimes network administraters may disable multicast on their LANs. This would allow you to do unicast discovery but not multicast, but once again it is really hard to say what your problem might be.

If you figure it out, please let us know what it was by posting a reply.

marcus bl?mel

Posts: 3
Nickname: sanchofx1
Registered: Mar, 2002

Re: multicast discovery fails Posted: Mar 14, 2002 3:29 PM
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Hi Bill,
In the meantime I have fixed the problem. I have found some very helpfull hints at the "jini-users" mail archive. It turned out to be a problem occuring with multible network interfaces in a single machine. (There is an isdn card on this machine, too.) Linux seems to enable multicast features on one of the cards only. So I went of with just adding another 'route' enabling multicast on the ethernet interface "by hand". Now everything works fine.

Thanks for you support, though!
Greetings,
Marcus Bl?mel

Jean-Pierre Dube

Posts: 1
Nickname: jpd
Registered: Mar, 2002

Re: multicast discovery fails Posted: Mar 27, 2002 5:41 AM
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Would you be kind enough to post the details of your solution. I'm running into the same situation

Thanks
JPD

marcus bl?mel

Posts: 3
Nickname: sanchofx1
Registered: Mar, 2002

Re: multicast discovery fails Posted: Apr 4, 2002 1:59 PM
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Hi Jean-Pierre,

Happed to find your message :-)
So here is what I found in the mail archive:
---------------------------------------------------

...Thanks to Patrick Dowler for helping me with this one. It seems that my
problem was due to a network setup error after all.


Patrick suggested that I try the following:


route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0


This opened a multicast route on my internal network, and everything works
fine. The strange thing is that when I disable eth1, I don't need to run
the line shown above, for multicast dsicovery to work on the internal
network. What I am guessing is that when I activate eth1, this interface
seems to be the one that becomes the default for multicast packets and is
why discovery will not work on eth0. By running the above line, I guess I
explicitly instruct multicast to go through eth0 and not the default eth1.
Does this make sense?...

[...]
-----Original Message-----
Hello all,


I have a Linux box running redhat 6.1 with two ethernet cards installed.
eth0 192.168.0.1 internal network
eth1 24.68.18.175 external network
default gateway 24.68.18.1


Now I want to start a Lookup Service that uses eth0 for 'multicast
discovery' to the internal network. I was thinking that this could be
accomplished by:


java -jar $JINI/reggie.jar http://192.168.0.1:8081/reggie-dl.jar policy
data -Dnet.jini.discovery.interface=192.168.0.1

--------------------------
I added the new route and all was fine...
Good Luck :-)

Fox Mulder

Posts: 1
Nickname: formatc
Registered: Jul, 2002

Re: multicast discovery fails Posted: Jul 26, 2002 3:09 AM
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Hello,
i'm having the same problem with multicast and 2
network-cards in a system. One is a PC with WinXP Prof in 10Mbit-Network and the other is a Win2000-PC, which is the router to the 100Mbit-Network. I have 2 tools a sender (to 224.0.1.41:1718) and a receiver. When I deactivate the 100mbit nic, then all works fine; in 1 segment of the network of course.
I've already found out, that I have to install the IGMP-Protocol on the router-pc. But on what NIC?? (I have tried both). Is this really necessary?? What configurations do I have to make to the other PC (XP)??

Hope someone can answer my questions. My email adress is fbi_78@hotmail.com

Greetings
Fox

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