Re: [ns] node address and MAC address

[Tarik Alj <aljtarik@cholla.inrs-telecom.uquebec.ca>]

>Date: Thu, 27 Jul 2000 09:11:36 -0700 (PDT)
>From: Yan Yu <yanyu@catarina.usc.edu>
>To: Tarik Alj <aljtarik@cholla.inrs-telecom.uquebec.ca>
>cc: yanyu@catarina.usc.edu, ns-users@isi.edu
>Subject: Re: [ns] node address and MAC address
>MIME-Version: 1.0
>
>> 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??

rarp stands for reverse arp; I wrote "some sort of rarp" because, unfortunatly, 
I don't think such a feature exist in NS-2 (at least I haven't heard of one). If 
you are using varp, you could maybe add a "reverse lookup" function, see 
varp.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
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>> 
>> >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 
>> 

Tarik Alj

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