Cell Relay Archive

["Zhonghua Zhang" <zzhang@bni.ca>]

> -----Original Message-----
> From: Navin Kumar Agarwal [mailto:navin@teil.soft.net]
> Sent: Thursday, January 21, 1999 11:39 AM
> To: zzhang@broadbandnetworks.com
> Cc: cell-relay@cell.ucs.indiana.edu
> Subject: Re: CR: RFC1577
>
>
> hi,
>
> >  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
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