All things related to multicast

[Hugh LaMaster <>]

On Wed, 14 Jul 1999, Mark Fullmer wrote:

> This is what I ended up using last night.  The list
> should probably also get applied in and out.
> 
> no access-list 110
> access-list 110 deny   ip any host 224.0.1.35
> access-list 110 deny   ip any host 224.0.1.22
> access-list 110 deny   ip any host 224.0.1.24
> access-list 110 deny   ip any host 224.0.1.60
> access-list 110 deny   ip any host 224.0.1.1
                                     ^^^^^^^^^

I suppose it is inevitable that there are disagreements
about these things, and, I just noticed the first one.

I see nothing malevolent about NTP multicast traffic,
and, in fact, as long as most of the people advertising 
are stratum 1 servers, they should probably be encouraged.
In NTP configuration terms, the end system joins 
this group by configuring "multicastclient".
Some of the servers out there should probably be 
shut off, but, for example, Time3.Stupi.SE is a
good stratum-1 server.  Up to reasonable limits,
with NTP, the more the merrier.  One of my systems
is seeing 19 NTP multicast servers "out there",
and, the daemon consumes tiny amounts of CPU time.

So, I would encourage folks NOT to filter 224.0.1.1
because I think it actually is useful traffic.
Especially, if the AS/campus LAN doesn't have its
own stratum 1 server running.

> access-list 110 deny   ip any host 224.0.1.2
> access-list 110 deny   ip any host 224.0.1.3
> access-list 110 deny   ip any host 224.0.2.2 
> access-list 110 deny   ip any host 239.0.0.0
> access-list 110 permit ip any any




--
 Hugh LaMaster, M/S 233-21,    Email: 

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