Hi, I am using pdns -2.26 with the aim of simulating real-world large scale networks. I have written tcl script which simulates a network consisting of 3 possible topologies - ring,tree and star with number of nodes input by user. I am facing a problem in ring topology only. Suppose I create a ring of say 100 nodes. Then packets get dropped as the default TTL value in class Agent in tcl/lib/ns-default.tcl is 32 and the packet has to make more than 32 hops to reach its destination. When I increased the default TTL value to a conveniently high value and compiled ns, and ran the program, there were no drops. However, I want to set default TTL value on run-time based on topology created, instead of setting an unnecessarily high default TTL. Can anyone please suggest how I can set default TTL for all nodes and is it possible to set TTL for selective nodes only?
Also, I was seeing other network simulators like GTNets and even NS 3 have provided support for following topologies : tree, star, dumbbell and grid,etc. but not ring. Is ring topology not ideal for representing real-world Internet traffic? Why are tree,star,dumbbell best for representing large-scale Internet traffic??
