Re: UDP Broadcast uses random source ports
Re: UDP Broadcast uses random source ports
- Subject: Re: UDP Broadcast uses random source ports
- From: "Quinn \"The Eskimo!\"" <email@hidden>
- Date: Wed, 31 Aug 2011 15:56:58 +0100
On 31 Aug 2011, at 14:40, Gordon Apple wrote:
> That may be true for busy networks. It is not always the case.
Actually, multicast is a win in pretty much all circumstances. This breaks down as follows:
o On all common networks (Ethernet, Wi-Fi, you name it), a multicast consumes as much network resources as a broadcast.
o Most MACs [1] will filter out multicasts that the host isn't listening for. This is typically done using a hash table in the hardware.
o If the hash table is full, the filtering has to be done by software. However, this worst case is no worse than broadcast's typical case.
So, in all cases multicast is no worse than broadcast, and in some cases it can be better.
The above discussion assumes link-local multicast; once you go off the local network, things get much more complex.
S+E
--
Quinn "The Eskimo!" <http://www.apple.com/developer/>
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
[1] That's MACs not Macs.
<http://en.wikipedia.org/wiki/Media_Access_Control>
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