Users Guide

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 differences between IPv4 and IPv6, and the Dell EMC 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 EMC Networking Operating System (OS) version supporting which features and
platforms, refer to Implementing IPv6 with Dell EMC Networking OS.
NOTE: Even though Dell EMC Networking OS listens to all ports, you can only use the ports starting from 1024 for IPv6
traffic. Ports from 0 to 1023 are reserved for internal use and you cannot use them for IPv6 traffic.
Topics:
• Protocol Overview
• Implementing IPv6 with Dell EMC Networking OS
• ICMPv6
• Path MTU discovery
• IPv6 Neighbor Discovery
• Secure Shell (SSH) Over an IPv6 Transport
• Configuration Tasks for IPv6
• Configuring IPv6 RA Guard
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 autoconfiguration
● Header format simplification
● 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.
Path MTU discovery
The size of the packet that can be sent across each hop in the network path without being fragmented is called the path
maximum transmission unit (PMTU). The PMTU value might differ for the same route between two devices, mainly over a public
network, depending on the network load and speed, and it is not a consistent value. The MTU size can also be different for
various types of traffic sent from one host to the same endpoint.
Path MTU discovery (PMTD) identifies the path MTU value between the sender and the receiver, and uses the determined
value to transmit the packets across the network. Path MTU, in accordance with RFC 1981, defines the largest packet size that
can traverse a transmission path without suffering fragmentation. Path MTU for IPv6 uses ICMPv6 Type-2 messages to
discover the largest MTU along the path from source to destination and avoid the need to fragment the packet. The
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422 IPv6 Routing