I am making the gnutella protocol layer for my cn project.The pings are working fine ,and ping cache is being updated and all.Now i have to send pongs .The thing I cannot understand is that pong follow ping path.So how will a node know which node to send the pong back .I know that we have to match pong id with ping id ,but ping cache has no ip/port.So how will a node decide which node to send the pong next .Urgent help needed.Thanx

What exactly do you mean?

Does the Ping cache you implemented not have IP/Port entries?

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You need to maintain a ping/pong routing table. All ids of pings you route need to be stored in a table together with the host it came from.
When you send a pong back or receive a pong you just lookup the id in your routing table to find the host you need to forward the pong to.
This generally works the same way as query and push routing. Here is a description of the routing:
http://rfc-gnutella.sourceforge.net/.../index.html#t4

But this is an outdated way to handle ping/pongs. Modern servents today use some kind of ping reduction technology (most often called Pong Caching) to reduce bandwidth and resources. There are various different implementations used by vendors. You find a basic description of Pong Caching here:
http://wiki.limewire.org/index.php?t...ng_Caching_GDF

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