Implementing IBM System Networking 10Gb Ethernet Switches

Chapter 2. IBM System Networking Switch 10Gb Ethernet switch features 71

PIM Sparse Mode

The behavior of PIM Sparse Mode is opposite of Dense Mode. The default behavior is to not

to flood the multicast traffic unless the downstream routers signal, by sending a PIM Join

message, that there are receivers on their directly connected networks interested in receiving

the multicast traffic.

For more information about PIM Sparse Mode, see RFC 4601, found at:

http://www.ietf.org/rfc/rfc4601.txt

2.5 IPv6

Internet Protocol version 6 (IPv6) is a network layer protocol intended to expand the network

address space. IPv6 is a robust and expandable protocol that meets the need for increased

physical address space.

For more information about the IPv6, see IPv6 Introduction and Configuration, REDP-4776.

2.5.1 IPv6 address format

The IPv6 address is 128 bits (16 bytes) long and is represented as a sequence of eight 16-bit

hex values, separated by colons.

Each IPv6 address has two parts:

򐂰 A subnet prefix that represents the network to which the interface is connected.

򐂰 A local identifier, which is either derived from the MAC address or user-configured.

The preferred hexadecimal format is as follows:

xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx

An example IPv6 address is:

FEDC:BA98:7654:BA98:FEDC:1234:ABCD:5412

Some addresses can contain long sequences of zeros. A single contiguous sequence of

zeros can be compressed to :: (two colons). For example, consider the following IPv6

address:

FE80:0:0:0:2AA:FF:FA:4CA2

The address can be compressed as follows:

FE80::2AA:FF:FA:4CA2

Unlike IPv4, a subnet mask is not used for IPv6 addresses. IPv6 uses the subnet prefix as the

network identifier. The prefix is the part of the address that indicates the bits that have fixed

values or are the bits of the subnet prefix. An IPv6 prefix is written in address/prefix-length

notation. For example, in the following address, 64 is the network prefix:

21DA:D300:0000:2F3C::/64

IPv6 addresses can be either user-configured or automatically configured. Automatically

configured addresses always have a 64-bit subnet prefix and a 64-bit interface identifier. In

most implementations, the interface identifier is derived from the switch's MAC address, using

a method called EUI-64.