P-660HWP-Dx Support Notes
All contents copyright © 2007 ZyXEL Communications Corporation.
82
Time Service in P-660HWP-Dx
There is no RTC (Real-Time Clock) chip so the P-660HWP-Dx should launch a
mechanism to get current time and date from external server in boot time.
Time service is implemented by the
Daytime protocol(RFC-867)
,
Time
protocol(RFC-868)
, and
NTP protocol(RFC-1305)
. You have to assign an IP
address of a time server and then, the P-660HWP-Dx will get the date, time,
and time-zone information from this server. You can configure it in Web
Configurator, Advanced Setup,
Maintenance -> System -> Time Setting.
12. Using IP Multicast
What is IP Multicast?
Traditionally, IP packets are transmitted in two ways - unicast or broadcast.
Multicast is a third way to deliver IP packets to a group of hosts. Host groups
are identified by class D IP addresses, i.e., those with "1110" as their
higher-order bits. In dotted decimal notation, host group addresses range from
224.0.0.0 to 239.255.255.255. Among them, 224.0.0.1 is assigned to the
permanent IP hosts group, and 224.0.0.2 is assigned to the multicast routers
group.
IGMP (Internet Group Management Protocol) is the protocol used to support
multicast groups. The latest version is version 2 (see RFC2236). IP hosts use
IGMP to report their multicast group membership to any immediate-neighbor
multicast routers so the multicast routers can decide if a multicast packet