Re: [ns] node address and MAC address

[Yan Yu <yanyu@catarina.usc.edu>]

> well from the mac header you should be able to get the source address (I 
> assume), wich should be that of node 1; then you would need to do do some sort 
> of rarp lookup to get the node id.
     ^^^^^^  could you pls elaborate more on that? Do you mean soem
function in arp.cc??
From the mac header, I can get the mac address of the previous node, but 
how can I get node id from its mac address? 
could you please give me more detials?
Thanks!!!
yan






















> 
> >Thanks!!!
> >yan
> >
> >
> >On Thu, 27 Jul 2000, Tarik Alj wrote:
> >
> >> What do you mean by "previous hop"? On an Ethernet segment there can't be 
> more 
> >> that one "hop" : from source address to destination address. So you probably 
> >> want the source address.
> >> 
> >> Exception with the LanNode : the LAN itself is a virtual-Node so packets look 
> >> like they are travelling from src to LAN to dst. 
> >> 
> >> >Date: Wed, 26 Jul 2000 14:29:13 -0700 (PDT)
> >> >From: Yan Yu <yanyu@catarina.usc.edu>
> >> >To: ns-users <ns-users@isi.edu>
> >> >Subject: [ns] node address and MAC address
> >> >MIME-Version: 1.0
> >> >
> >> >
> >> >My problem is to implement a reliable link layer. IN order to send a  
> >> >hop-by-hop link layer ack back to the previous hop, I reverse the MacSA
> >> >and MacDA in the packet, and send it back. But this is not enough for
> >> >link layer. By reversing the macSA and macDA, the packet can reach the mac
> >> >layer of the previous node, it can NOT reach the  link layer of the
> >> >previous
> >> >node. I guess there is some kind of filter which will filter out any
> >> >packets whose dst address is diffrent from myself. So I change the dst
> >> >address in packet to the MAC address of the previous node (i do not know 
> >> >how to get the node address of previous hop node), It works when the node
> >> >address and MAC address of the nodes are the same. However, The packet
> >> >won't be able to get to the link layer if the Mac address happen to be
> >> >different from the node address..
> >> >In order to get around this,
> >> > my question is:
> >> >1. How to get to know the node address of the previous hop node?
> >> >( I use wired LAN..)
> >> >or how to get the node address from its MAC address?
> >> >
> >> >2. if I can not get the above information, can I change the node address
> >> >arbitrarily, so that the node address can be the same as the MAC address?
> >> >If I write up such a function myself to change node address, will the
> >> >change mess up the normal operation in ns, such as routing?
> >> >
> >> >THanks a LOT for any feedback in advance!
> >> >yan 
> >> >
> >> >
> >> >
> >> 
> >> Tarik 
> >> 
> 
> Tarik 
>