Hello, Sorry about the inconvenience, but another network administrator has told me that, indeed, some of our intermediate switches are configured to selectively filter multicast traffic to avoid overloading. So, it seems that this was the root of our problem.
That would explain why using Unicast it always works, and using Multicast it only works "sometimes" (maybe depending on traffic load and the filtering policy stablished in the devices, which was not created by the guy to whom I've been talking to). Thank you very much for all your replies. I've learned a lot about Reggie's behaviour in the last few days, so I'm open to solve issues related to the one that I've faced, as long as I could. Regards. 2011/10/5 Sergio Aguilera Cazorla <[email protected]> > Hello, > > No, we are not using VLAN, all the computers in the office belong to the > same LAN. > > Regards. > > > 2011/10/5 richard nicholson <[email protected]> > >> Sergio >> >> As you using layer II VLAN's between your physical switches? If so - make >> sure your network >> folks have IGMP turned on - on the switch interlinks. >> >> Cheers >> >> Richard >> >> >> On 5 Oct 2011, at 09:38, Sergio Aguilera Cazorla wrote: >> >> > Hello, >> > >> > Our network administrators say that *our company's switches do not block >> > multicast or broadcast traffic*. To check if this it's true, we've >> forgotten >> > about Reggie and we've written a little Java program that simply uses a >> > MulticastSocket to send packets to the multicast IP *224.0.1.84 and >> > attacking the port 4160*. Of course, this program failed in the network >> > office, while it worked perfectly on my home's network. >> > >> > We are completely sure that it's a problem related to multicast packets. >> > Maybe it's related to Windows XP or 7 Firewall? In the company there is >> a >> > Group Policy commanding the Firewall, but we can define some exceptions >> and >> > we have the multicast/broadcast response enabled. Is that enough, or is >> > there some other issue that remains hidden? >> > >> > Please, any hint is welcome, because our goal is to deploy this software >> in >> > a production environment, not only in a domestic network! >> > >> > Thanks and regards >> > >> > >> > >> > 2011/9/29 Christopher Dolan <[email protected]> >> > >> >> Yes, most enterprise switches block multicast by default. That's >> probably >> >> your issue. >> >> >> >> Another possible issue is reverse DNS. If reggie is broadcasting a >> private >> >> hostname or IP address for other machines to call back to it, then it's >> not >> >> going to work. We've also had issues with dual-NIC servers where >> clients >> >> always try to connect to the primary NIC (as specified in the Windows >> >> interface binding order) and do not fail over to the secondary NIC. The >> >> usual cause of that problem is passing a null host to >> >> TcpServerEndpoint.getInstance() because in that code path, JERI just >> picks >> >> the first IP address from a reverse DNS lookup. The solution in that >> case is >> >> to instead pass the results of >> >> InetAddress.getLocalHost().getCanonicalHostName() as the hostname, or >> >> hard-code the public host name. >> >> >> >> I'm suspicious of your "just once" result. Maybe you changed the group >> >> name? Remember that the group is case-sensitive. >> >> Chris >> >> >> >> >> >> -----Original Message----- >> >> From: Sergio Aguilera Cazorla [mailto:[email protected]] >> >> Sent: Thursday, September 29, 2011 1:16 PM >> >> To: [email protected] >> >> Subject: Re: Reggie's visibility in discovery process >> >> >> >> Hello, >> >> >> >> At last we could perform some testing on Reggie's discovery using >> multicast >> >> protocol. I can provide the following results: >> >> >> >> - The program performs perfectly when we make a Unicast discovery, >> >> attacking >> >> directly the URL where the Lookup service is located. >> >> >> >> - We can ping the two machines. Even, we can acces the folder server by >> the >> >> HTTP server, and get the reggie-dl.jar classfiles needed to communicate >> >> with >> >> the Lookup. >> >> >> >> - All machines in the office are Windows XP SP3 and Windows 7. None of >> the >> >> combinations server/client XP-7 has thrown a good result. >> >> >> >> - We are communicating through switches in the LAN of a enterprise. Do >> you >> >> think that multicast packets are bein blocked by intermediate nodes? >> >> >> >> - The most misteryous fact: we could perform multicast discovery >> >> succesfully >> >> *just once*, the first time we tried. That's suspicious, is there some >> >> class >> >> or service that remains hidden and doesn't allow you to perform >> multicast >> >> discovery more than once? >> >> >> >> Any help on reggie's weird behaviour is very welcome. If I can solve >> this >> >> problem, no doubt I will write a short explanation for the community, >> >> because I think it has to be a very common problem. >> >> >> >> Regards. >> >> >> >> >> >> >> >> 2011/9/22 Иван Бишевац <[email protected]> >> >> >> >>> 1. Could you ping two machines? >> >>> 2. Which operating system you use? >> >>> 3. Are you communicating through router? >> >>> >> >>> >> >> >> > >> > >> > >> > -- >> > *Sergio Aguilera* >> >> > > > -- > *Sergio Aguilera* > -- *Sergio Aguilera*
