Cell Relay Archive

[Navin Kumar Agarwal <navin@teil.soft.net>]

>  I am reading rfc1577. It seems to me only when a host has connection
with 
> the server, the server will send InATMARP to find its IP address, 
	that is correct.
>or the host registers itself to the ATMARP?  
	this is not true as per rfc1577, but true as per the new rfc2225, 
which obsoletes rfc1577, it says the first arp packet goes from the CIP 
client side.

>My question is: Does ATMARP broadcast request to all the hosts to 
>find unknow IP address? 

	No it does not performs any broadcast, infact if the ATMARP Server
finds that there is no entry in its ARP table for the asked IP address, it
generates an ARP_NAK message. See 2nd para Section 6.3.

	Now I will try to answer the why part of your question. (ie. why
not broadcast??). My argument is that, the server will never decide to do 
broadcasting. The reason is as follows: 

For broadcasting a particular ARP request, the server need to have 
point-to-multipoint connection with all the CIP clients (as in LANE, BUS 
maintains a Multicast Forward VCC). 
	Suppose the server receives an ATMARP_REQUEST for IP address of a 
client X. It will chose the option of broadcasting to all the clients 
only if it assumes that X is up. Now if X is up, its entry would be 
present in the ARP table of server. Hence the server would have found 
entry for X upon reception of ATMARP_REQUEST for X and it would have not 
decided to do broadcasting. Now if the server assumes that X is down, 
then obviously there is no point in going for broadcast.
	SO in either case, its not possible for a server to go for 
broadcasting to resolve any IP address.
 
>If not, how to set a connection to a host in another LIS? 

	THe IP of client only will decide whether the destined client is 
in the same LIS or not. Once it has decide that it is not, it will send 
an ATMARP_REQUEST for the IP address of a router, which will probably be 
able to forward its packet to the destined client.

	Hope this helps. Get back to me in case of disagreement.

Regards,
Navin