Re: [ns] packet headers!

[Lloyd Wood <l.wood@eim.surrey.ac.uk>]

On Sun, 27 Aug 2000, Sowmya Manjanatha wrote:

> I am simulating a simple toplogy with one source node and one
> destination as shown below and a TCP agent with a Telnet source is
> attached to the source node.   
> 
>             Source_node ----------- Dest_node
> 
> The NS manual indicates that
> 
> hdr_cmn::access(packet)->size_ 
> 
> is the size of the (Application + IP + TCP) layer. 

If you're using a one-way source, you don't get realistic header
sizes.

Read:
http://www.isi.edu/nsnam/archive/ns-users/webarch/2000/msg03132.html


> 2. Also, what is the link layer used in NS by default ?  

depends on how you configure your nodes using the new node API
introduced in ns 2.1b6.

http://www.isi.edu/nsnam/ns/doc/node179.html

>    in a simple
>    script such as the one provided in Marc Greiss's tutorial, is a link
>    layer header simulated as part of the packet at all?

no. ns shows its origins as an IP-focused simulator; it's been moving
down and filling out the network stack more recently, though.

L.

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>