On Friday 05 December 2003 12:39, Joshua Banks wrote: > For some reason I always assumed that for anytype of IP packet to be > routed out to the internet that you needed a Layer 4 helper (TCP or > UDP) to acheive the transport? Is that true or can just IP layer 3 > protocols treverse the internet with out the need for a Layer 4 > transport helper?
Routers don't care about anything other than IP (L3) unless doing packet filtering. > Take ICMP for example (a ping). This is a Layer 3 protocol. Now, I > thought that "windows" pc's used tcp/icmp to transport pings or > tracert's and linux/unix (to include Cisco routers) pc's used udp/icmp > to transport pings or traceroute's. ICMP is a Layer 4 protocol. There is no such thing as tcp/icmp or udp/icmp. Some implementations of tracert will use udp packets instead of icmp, however. > 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. If a packet has an IP header it might get to point B but there are no guarantees. It's up to the layer 4 protocol implementation to deal with this (or not). Jason -- [EMAIL PROTECTED] mailing list
