ZyXEL Communications Corporation P8802T Manual Do Utilizador

 Chapter 4 WAN

Basic Home Station VDSL2 P8802T User’s Guide

IP packets are transmitted in either one of two ways - Unicast (1 sender - 1 recipient) or Broadcast 
(1 sender - everybody on the network). Multicast delivers IP packets to a group of hosts on the 
network - not everybody and not just 1. 

Internet Group Multicast Protocol (IGMP) is a network-layer protocol used to establish membership 
in a Multicast group - it is not used to carry user data. IGMP version 2 (RFC 2236) is an 
improvement over version 1 (RFC 1112) but IGMP version 1 is still in wide use. If you would like to 
read more detailed information about interoperability between IGMP version 2 and version 1, please 
see sections 4 and 5 of RFC 2236. The class D IP address is used to identify host groups and can be 
in the range 224.0.0.0 to 239.255.255.255. The address 224.0.0.0 is not assigned to any group 
and is used by IP multicast computers. The address 224.0.0.1 is used for query messages and is 
assigned to the permanent group of all IP hosts (including gateways). All hosts must join the 
224.0.0.1 group in order to participate in IGMP. The address 224.0.0.2 is assigned to the multicast 
routers group. 

At start up, the VDSL Router queries all directly connected networks to gather group membership. 
After that, the VDSL Router periodically updates this information.

Use Domain Name System (DNS) to map a domain name to its corresponding IP address and vice 
versa, for instance, the IP address of www.zyxel.com is 204.217.0.2. The DNS server is extremely 
important because without it, you must know the IP address of a computer before you can access 
it. 

The VDSL Router can get the DNS server addresses in the following ways.

The ISP tells you the DNS server addresses, usually in the form of an information sheet, when you 
sign up. If your ISP gives you DNS server addresses, manually enter them in the DNS server fields.

If your ISP dynamically assigns the DNS server IP addresses (along with the VDSL Router’s WAN IP 
address), set the DNS server fields to get the DNS server address from the ISP.

The 128-bit IPv6 address is written as eight 16-bit hexadecimal blocks separated by colons (:). This 
is an example IPv6 address 2001:0db8:1a2b:0015:0000:0000:1a2f:0000.

IPv6 addresses can be abbreviated in two ways:

• Leading zeros in a block can be omitted. So 2001:0db8:1a2b:0015:0000:0000:1a2f:0000 can 

be written as 2001:db8:1a2b:15:0:0:1a2f:0. 

• Any number of consecutive blocks of zeros can be replaced by a double colon. A double colon can 

only appear once in an IPv6 address. So 2001:0db8:0000:0000:1a2f:0000:0000:0015 can be 
written as 2001:0db8::1a2f:0000:0000:0015, 2001:0db8:0000:0000:1a2f::0015, 
2001:db8::1a2f:0:0:15

 or 2001:db8:0:0:1a2f::15.

Similar to an IPv4 subnet mask, IPv6 uses an address prefix to represent the network address. An 
IPv6 prefix length specifies how many most significant bits (start from the left) in the address