¿Tenéis problemas con videoconferencia iChat?

[delmod]

Al fín solucioné mi último problema con iChat. Cómo recordaréis más arriba desde tres ubicaciones A, B, C, conseguía establecer videoconferencia con el mundo exterior pero entre dos de ellas B y C no conseguía establecerla de ninguna forma. Leí todo lo que encontré al respecto e hice una consulta en los foros técnicos de Apple, donde me remitieron a esta página http://www.ralphjohnsuk.dsl.pipex.com/pa...tain_Buddy. El problema no era tan extraño y ocurre a veces. Yendo hacia la parte concreta dice:

Can not connect to a certain Buddy.

In some situations you will be able to chat to one friend ("a" to "b") but friend "c" can't chat to "b". Worse still you are friend "b" and are isolated from one Buddy whilst they can chat to everybody else and so can you. Apart from the first FIX it is likley to be a Firewall or Router/modem problem.

More recent information and better understanding by me of how NAT and then the methods that rely on NAT to open the ports such as Port Forwarding, Triggering and DMZ work together - points to this being a NAT related problem where two modems (or the routers behind them) are incompatible with the one at the other end. This is because different Manufactures use different methods to enable NAT. The realistic FIXes are the one about using UPnP and the "Bottom Line" to egt one end to "Play Nicely" with the other. I leave the other information here as they are still goods hints about checking settings.

Check that you are Allowing and not Blocking a Buddy
FIX: Go to the iChat menu -Preferences - Privacy section and make show you are Allowing and not Blocking your Buddy.

Check for Firewalls.
FIX: Check your computer, router and, if separate, your modem for firewalls. Make sure the following ports are open:- 5060, 5190, 5297, 5298, 5353, 5678, 16384-16403 in all devices.

Check for router or modem problems
FIX: Your Router and or Modem may be able to perform Network Translation (NAT) or Port Forwarding which is essentially the same thing.

The ports need to be open for UDP protocol in all cases and TCP in some. See Apple Doc 93208 for complete details.

If you have the Univeral Plug n Play (UPnP) setting use that as it will dispense with the need to set NAT/Port Fowarding settings.

Find out from Manuals/ReadMes/websites how your router or modem perform ad achieves these settings. Also go to this site's Apple Related Discussions, in Britain, to ask other users and experts how to set up your router/modem.

If you have an Airport or other WiFi device you will have to set it to be a 'bridge'. In the case of an Airport device this is a case of deselecting the check box for "Distribute Addresses" in the Airport Utility when you set it up. Other WiFi devices should be able to be set to a similar configuration in it's set up session.

An option on 4) above is to make the modem or first router to be a bridge and have any other device after that perform NAT/Port Forwarding.

Some routers and Modems work not by Port Forwarding but by using Trigger ports. In these cases make sure you have identified port 5678 as the first Trigger. This Trigger should open port 5678, 5060, 16384-16403. In addition to this you need to have port 5190 trigger itself for Text chats and sending files. If you intend to use Rendezvous then you also need to set these three port to trigger themselves: 5297, 5298 and 5353. (EDIT September 2006: and 5220, 5222 and 5223 for Jabber).

Check for router compatibilty.
FIX: In some cases no matter what you do two routers or modems will not 'play nicely' together. This is because not all internet connection devices perform NAT the same way.

Try a firmware update

The UPnP setting. Or Port Triggering.

Re-ordering your devices. (applies to VoIP devices)

Setting a different device as the DHCP server.
In many cases the only option is to try another device.

De todo ello me quedé con la parte final, "a veces dos módems son incompatibles". Revisé los dos módems y bueno... un poquito anticuallas ya eran. Como habían funcionado hasta ahora, ¿para qué cambiarlos?. Tras cambiar los dos por modelos más actuales....¡Voilà!. Todo funciona.

Así que ... a por otra cosa mariposa.