RE: Clarifications with RFC 3077

Hi Emmanuel Duros,
      Good Day. Thanks for your Clarifications.

Regarding Q 2)

Yep, Our Return Link is unidirectional, and TX and RX are 2 different 
interfaces.

My Clarification now might be silly, but just to doubt check my understanding 
:)

RCS System with both TX and RX port.

Scenario 1: RCS Sytem sends/response to Feeder (Send Only). The packet is 
Encapsulated and based on the Routing table it chooses Tx Port(Return Link) or 
RCS System bi-directional interface targeting Feeder bidirectional interface.
	In Case if Tx Port is selected, there should be a Gateway which receives the 
Encapsulated packet from RCS System and forwards to the feeder bidirectional 
interface, just IP Forward.

Scenaio 2: RCS System sends/response to Feeder( Receive capable feeder). The 
packet is not Encapsulated, just sends via the TX port(Return Link) to the 
Feeder.

so Encapsulation Decisions are taken based on the DTCP table, "feeder type 
information" in the RCS System..

Note: All the Scenarios are not IP forwarding


Thanks and Best Regards,
William StanisLaus.

>===== Original Message From Emmanuel Duros <[email protected]> =====
>Hello William,
>
>On Tue, 2002-10-29 at 12:01, William StanisLaus wrote:
>> Hi all,
>>
>>     I am a newbee to UDLR technology. I have few clarifications with RFC 
3077.
>>
>> Can you help me in understanding the concept.
>> here we go.....
>>
>> 1)
>>
>> In Section 7
>> "The number of feeds is expected to be relatively small (Section 3),
>> so at every feed the list of all feeds is configured manually."
>>
>> In Section 7.1
>> When Feed multicasts the DTCP Hello Message, it passes the Feed Type
>>
>> i.e.
>>    F (1 bit): bit indicating the type of feed:
>>       0 = Send-only feed
>>       1 = Receive-capable feed
>>
>>
>> So the Reciever can maintain the Feed type in the DTCP routing table.
>> In Such cases,
>> for Scenario 2: "A receiver can send a broadcast/multicast packet on the
>> link to all nodes (point-to-multipoint)"
>>
>> Section 6.2.2 (3)
>> As of now, Receiver sends packets to be broadcasted/multicasted to the 
default
>> feed and the default feed broadcast/multicast the packet to the other Feed 
&
>> Receivers.
>>
>>
>> Clarification :-
>>
>> When the Receiver maintains the Feed types, which is dynamic at any moment,
>> why Receiver is not multicasting to all the Feeds which are Send only?
>
>The main reason I see is that it would be costly in term of bandwidth
>for the receiving site. A copy of every multicast packet would have to
>be tunneled from the receiver to each Send-only feed. It can get really
>bad for the receiver if it has a low speed return link such as GSM or
>RTC.
>
>It is easier for the operator to set up high speed links between the
>feeds and let them make the duplication of packets...
>
>> It can also have a default Feed which forwards the packet to all receivers 
and
>> receive capable Feeds.
>>
>>
>> The clarification is because, we have the overhead of encapulation at the
>> receiver side and sending to the default feed which decapulate and again
>> encapulate to send to Send only Feeds. Also in the Feeds the list of
>> other feeds are manually configured i.e. Static. Might be broken at any 
time.
>>
>>
>> 2)
>>
>> In the RFC 3077 which explaines about the Feeds , i.e. Send only and 
Recieve
>> capable Feeds. But for receivers it is always targeted as Receive only. 
Just
>> imagine a RCST with send capable receivers i.e. which has both Tx and Rx 
port.
>>
>> What are the configurations in the UDLR if the receiver happens to be send
>> capable.
>>
>
>The receiver you are describing is pretty much similar to a receiver
>whose return link is unidirectional. Am I right ? It seems the TX and RX
>are 2 differents interfaces...
>
>This situation can be handled by UDLR although RFC 3077 says the
>receiver needs a bidirectional interface to send GRE to the feed. In
>fact, as long as the return link can carry IP datagrams from the
>receiver to the feed, the UDLR protocol will work. We've been using some
>DVB-RCS systems with UDLR and it works pretty well.
>
>
>>
>>
>> Thanks and Best Regards,
>> William StanisLaus.
>>
>> _______________________________________________
>> UDLR mailing list
>> [email protected]
>> http://www.udcast.com/mailman/listinfo/udlr
>
>Regards,
>>
>--
>Emmanuel Duros                  http://www.udcast.com
>2455 Route des Dolines BP355  | Tel : +33 (0)4 93 00 16 60
>06906 Sophia Antipolis France | Fax : +33 (0)4 93 00 16 61
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>
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