5. IP Network Interfaces
ROX™ v2.2 User Guide
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RuggedBackbone™ RX5000
5. IP Network Interfaces
This chapter familiarizes the user with:
• IPv6 Fundamentals and IPv6 Neighbor Discovery
• Adding VLAN Interfaces to Switched Ports
• Configuring IP Address Source and ProxyARP for Switched and Non-switched Interfaces
5.1. IPv6 Fundamentals
Version 6 of the Internet Protocol (IPv6, RFC 2460) has been designated to replace IPv4 throughout the
Internet. Some important changes that IPv6 introduces relative to IPv4 fall into the following categories:
5.1.1. Addressing
IPv6 addresses are four times the length of IPv4 addresses, at 128 bits, to be used as 64 bits of network
and 64 bits of host address. The larger address space allows much greater flexibility in hierarchical
network definition and routing.
The IPv6 packet header has been simplified relative to IPv4 in order to simplify and therefore speed the
processing of packets by routing nodes. It also features more efficiently encoded options and greater
flexibility in creating extensions.
5.1.2. Security
Security has been designed into IPv6, rather than being treated as a component that must be added
to existing IPv4 network stacks.
5.1.3. IPv6 Address Scopes
There are three scopes of IPv6 addresses named Link Local, Unique Local and Global. A Link Local
address is automatically assigned to any IPv6 capable interface. This address is mandatory for the
devices on the same link to communicate with each other.
The link local address begins with “FE80” in the first 10 bits of an IPv6 address and the
address is not routable. The scope for Unique Local address is within enterprise networks. It
identifies the boundary of private networks within an organization. Example of a link local address:
FE80:0000:0000:0000:020A:DCFF:FE01:0CCD
Unique Local addresses are similar to private IPv4 addresses and they are not routable on the Internet. A
Unique Local address consists of the first 7 bits as the site address starts with “FD”, the next 1 bit set to 1
meaning locally assigned, next 40 bits as the Global ID to identify a company, next 16 bits as the Subnet
ID to identify the subnets within a site and it is usually defined based on hierarchical plan, and finally
the last 64 bits for the Interface ID. Example of a unique local address:
FD00:ABAB:CDCD:EFEF:
020A:DCFF:FE01:0CCD
The Global IPv6 addresses are routable and they are interned to be used on the Internet. In order to
allow address aggregation the global addresses are structured in hierarchical order. A global address
is identified by the first 48 bits specified by the service provider as the global routing prefix in which the
first 3 bits of the address start with 001 (2000::/3), the next 16 bits after the global routing prefix are used
to define subnets and the last 64 bits are used for Interface ID to define a host. Example of a unique
local address:
2001:0CCD:3456:789A:8A9C:BCAB:023A:1234
5.1.4. IPv6 Multicast Addresses
In IPv6 multicast addresses are widely used. The use of broadcast address is removed in IPv6, instead
IPV6 multicast addresses are used for neighbor discovery and route advertisement. An IPv6 multicast
address starts with first 8 bits all set to 1 (FF), next 4 bits to define the Lifetime (0 - Permanent, 1 -
