On Thu, 2003-12-04 at 21:39, Joshua Banks wrote: > Hello, > > After running Ethereal and watching a packet dump in real time, I only > saw ICMP being used and NO UDP or TCP. Is ethereal missing something or > am I? > > If some types of IP packets don't need Layer 4 transport helpers like > Tcp or Udp then what are some examples (or types of apps) that utilize > only IP, and still get from point A to point B without the help of Tcp > or Udp.
It's been awhile since I studied this in depth, but basically, IP and ICMP are the protocols that are routed throughout the Internet. A basic router that only cares about forwarding the IP datagram on will just look at the IP header and will not care about the TCP or UDP headers within the IP datagram. It is only once you start wanting to differentiate based upon what is being routed, that the routers start to look at the protocol headers in the IP datagram that they are transporting. Yes, it is possible to design another layer 4 protocol to reside on top of IP and have it routed. However, I am not aware of any that have been created and placed into use. (I'm sure that it has probably been done, I'm just not aware of it) Regards, Paul -- [EMAIL PROTECTED] mailing list
