Service Manual

23
IPv6 Routing
Internet protocol version 6 (IPv6) routing is the successor to IPv4. Due to the rapid growth in internet users and IP addresses, IPv4
is reaching its maximum usage. IPv6 will eventually replace IPv4 usage to allow for the constant expansion.
This chapter provides a brief description of the dierences between IPv4 and IPv6, and the Dell Networking support of IPv6. This
chapter is not intended to be a comprehensive description of IPv6.
NOTE: The IPv6 basic commands are supported on all platforms. However, not all features are supported on all platforms,
nor for all releases. To determine the Dell Networking Operating System (OS) version supporting which features and
platforms, refer to
Implementing IPv6 with Dell Networking OS.
NOTE: Even though Dell Networking OS listens to all ports, you can only use the ports starting from 1024 for IPv6 trac.
Ports from 0 to 1023 are reserved for internal use and you cannot use them for IPv6 trac.
Protocol Overview
IPv6 is an evolution of IPv4. IPv6 is generally installed as an upgrade in devices and operating systems. Most new devices and
operating systems support both IPv4 and IPv6.
Some key changes in IPv6 are:
• Extended address space
• Stateless autoconguration
• Header format simplication
• Improved support for options and extensions
Extended Address Space
The address format is extended from 32 bits to 128 bits. This not only provides room for all anticipated needs, it allows for the use of
a hierarchical address space structure to optimize global addressing.
Stateless Autoconguration
When a booting device comes up in IPv6 and asks for its network prex, the device can get the prex (or prexes) from an IPv6
router on its link. It can then autocongure one or more global IPv6 addresses by using either the MAC address or a private random
number to build its unique IPv6 address.
Stateless autoconguration uses three mechanisms for IPv6 address conguration:
• Prex Advertisement — Routers use “Router Advertisement” messages to announce the network prex. Hosts then use their
interface-identier MAC address to generate their own valid IPv6 address.
• Duplicate Address Detection (DAD) — Before conguring its IPv6 address, an IPv6 host node device checks whether that
address is used anywhere on the network using this mechanism.
• Prex Renumbering — Useful in transparent renumbering of hosts in the network when an organization changes its service
provider.
NOTE: As an alternative to stateless autoconguration, network hosts can obtain their IPv6 addresses using the dynamic
host control protocol (DHCP) servers via stateful auto-conguration.
NOTE: Dell Networking OS provides the exibility to add prexes on Router Advertisements (RA) to advertise responses
to Router Solicitations (RS). By default, RA response messages are sent when an RS message is received.
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IPv6 Routing