Why Did Pc-B Receive The Global Routing Prefix And Subnet Id That You Configured On R1?

Why did PC-B receive the Global Routing Prefix and Subnet ID that you configured on R1?

Answer: on R1 the IPv6 is part of the all-router multicast group, FF02::2 permits it to send the RA (router advertisement) messages along with global network address and the subnet ID information to the nodes on the LAN. R1 can send the link-local address, fe80::1 as the default gateway. For as long the prefix length is 64 bits the PCs will receive the IPv6 addresses and the default gateway through SLAAC.

The global routing prefix is described as the value which is allocated to the site while the subnet ID act as the identifier for the link of the site. For the determination of the Interface link, an Interface ID is present, it is also needed to be unique for the prefix of the subnet.

Except for form the global unicast which initiate with B’000’ consist of the 64-bit interface ID field (n + m=64) while the other one with B’000’ have no constraints on the length of the structure of the interface ID field.

For example global unicast addresses that begin with B’000′ are IPv6 deal with embedded IPv4 addresses. These consist of IPv4-mapped IPv6 addresses and IPv4-well-matched IPv6 addresses.

The global unicast is divided into three parts such as :

• Global routing prefix.
• Subnet ID.
• Interface ID.

Global Routing Prefix

Global routing prefix is allocated by the provider as ISP to the customer site. Recently RIRs allocate a/48 global routing prefix to the user. The customer varies from the enterprise to the household which is enough for the customers.

For example an IPv6 address 2001:0DB8: ACAD: :/48 contain a prefix that describes the first 48 bits (3 hextets) (2001:0DB8: ACAD) as the prefix part of the address. while the double colon which presents before /48 shows the other part of the address contains all 0’s.

Subnet ID:

The ID is for a determination of the subnet in the site by the organizations.

Interface ID:

The interface ID of IPv6 same as the host part of the IPv4 address. the term is used due to a single host might have multiple interfaces, with more than one IPv6 address.

The sixteen bits of subnet ID permit every web website online sizable flexibility in growing subnets that mirror the web website online’s community structure. For example: 

• A smaller company can simply set all of the bits withinside the Subnet ID to 0 and feature a “flat” inner structure.
• A medium-sized company may want to use all of the bits withinside the Subnet ID to carry out the equal of “straight” subnetting below IPv4, assigning a distinctive Subnet ID to every subnet. There are sixteen bits here, so this lets in a whopping 65,536 subnets.