All things related to multicast

[Toerless Eckert <>]

On Fri, Jun 22, 2001 at 04:41:24PM -0700, ken lindahl wrote:
> Alan mentioned ntp specifically and 224.0.1.1 is not on the list.
> a couple months ago our ntp guy asked that ntp multicasts be blocked
> at the edge of campus, so i added 224.0.1.1 to the msdp filters. as
> i understand it, the issue is that workstations listening to ntp multicast
> may choose to sync with a distant ntp server instead of a closer one. we
> found numerous ucb hosts syncing with remote ntp servers rather than one
> of the campus stratum 1 or 2 servers. the ntp docs actually recommend using
> some sort of authentication to restrict the set of trusted servers,
> it was apparent that this was not going to happen here soon, so we
> added the ntp group to our msdp sa filters. this seems to be a local
> decision, not something to recommend globally.

Reminds me that IOS can also receive NTP via multicast...

Ok, added a note about how to handle 224.0.1.1