MAC/NPA question

[P.Pillai@Bradford.ac.uk]

Hi Gorry,

I would be grateful if you could help me with the following doubts related to
the MAC/NPA address:

? Section 4.5 in the ULE RFC states that the destination address field is
optional. What is the main reason that drives it? Is it only because there is a
higher layer address (e.g. IP address) that can be used for filtering?

? Is this destination address the MAC address (i.e. the actual physical hardware
address) of the DVB receiver or is any address that is used at layer 2 for
identification (i.e. this address can be generated dynamically)?

? The section also states that ?the destination address would be present for
Unicast IP packets destined to routers that are sent using the shared link
(i.e. where the same link connects multiple receivers)?. Which link is being
referred to here?

? Does the above case refer to two IP routers connected to a same DVB receiver?
Even in this case the DVB receiver would de-capsulated the IP datagram from the
ULE packet and could then encapsulate it into an Ethernet frame with the source
Ethernet address being that of the DVB receiver. And an ARP cache can be
maintained in the DVB receiver which can used to get the destination MAC
address of the router.

? Am I right in saying that the destination address would not be present in most
of the cases (so maybe default case) but would be present for some exceptional
cases?

Regards
Prashant

P.S. HAPPY NEW YEAR to all.

-- 
Prashant Pillai
Research Assistant
School of Engineering, Design and Technology
University of Bradford
Bradford, BD7 1DP
West Yorkshire
United Kingdom
Phone: 0044-1274-233720
email: p.pillai@bradford.ac.uk
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