IPv6 / IPv4 Overview

With the introduction of feature F-1253 IPv6 Support, the IMG 2020 now supports the IPv6 protocol. The stack employed for this functionality is a dual IPv4/IPv6 network stack that is IPv6 Ready Phase II certified that supports mixing the IPv6 and IPv4 protocols. For example, SIP Signaling can be configured for IPv6 where the RTP Media can be configured for IPv4. Feature F-1253 also adds IPv4 to IPv6 conversion as well as IPv6 to IPv4 conversions. This functionality allows the IMG 2020 to send and receive IPv4 or IPv6 formatted messaging between IPv4 and IPv6 networks.

The new functionality is supported when utilizing SIP Signaling along with its associated RTP and DNS Server/Client and is supported on all of the ethernet interfaces on the rear of the system. Refer to the table below for a list of what applications are supported using IPv6, IPv4, or both.

Summary of Supported IPv6 functionality

The information below is a summary of how IPv6 is supported on the IMG 2020

• The Network stack running on the CPU will be setup as a dual stack supporting both IPv4 and IPv6 simultaneously.

• Each of the interfaces, (Data A, Data B, Control) will allow two Media 0 and/or two Media 1 endpoint IP addresses to be configured for streaming media. The Media IP addresses configured on each Media 0 endpoint has got to be the same type (IPv4/IPv6) and the Media IP addresses configured on each Media 1 endpoint has got to be the same type (IPv4/IPv6) as well.

• If IPv6 format is configured on the first instance of Media 0 (Say Data A interface), the IPv6 format must be configured on the second instance as well. This also goes for IPv4. The format (IPv6 or IPV4) must be the same for the first instance of Media 0 as well as the second instance of Media 0. Refer to table below.

• If IPv4 format is configured on the first instance of Media 1 (Say Data A interface), the IPv4 format must be configured on the second instance as well. This also goes for IPv6. The format (IPv6 or IPV4) must be the same for the first instance of Media 1 as well as the second instance of Media 1. Refer to table below.

• The maximum number of IP addresses that can be configured for Media is 4. Refer to table below.

• The IMG 2020 will continue to boot on an IPv4 network. The IP address assigned to the CTRL interface during the bootup process will need to be configured as an IPv4 address. Any applications utilizing this IP address will need to be configured for IPv4.

• The IPv6 format is supported on IP addresses configured as a Service IP address and configures for SIP Signaling. H.323 Signaling will still require utilizing the IPv4 format.

• If Media or Service IP address is configured for IPv6, all IPv4 packets will be dropped.

• If Media or Service IP address is configured for IPv4, all IPv6 packets will be dropped.

• TLS and SRTP are supported utilizing the IPv6 format.

• If IPv6 is tunneled within IPv4,the packets will be dropped.

• If IPv4 is tunneled within IPv6, the packets will be dropped.

• As per RFC 5954, the IMG 2020 will accept a SIP message that uses the incorrect ":::" notation.

Supported RFC's

The table below displays the RFC's that encompass the supported IPv6 / IPv4 functionality.

Subnet Prefix

The Subnet Prefix is displayed using the CIDR notation (/) and identifies the range of ip addresses that make up a subnet or group of IP addresses on a particular network. The Subnet Prefix used represents a left to right bit counter. When configuring IP addresses using IPv4, the allowed values of the Subnet Prefix range from 0 to 32 with the default value being 24. When configuring IP addresses using IPv6, the allowed values of the Subnet Prefix range from 8 to 128 with 64 being the default value.  How the Subnet Prefix works in the individual objects is explained below. A Subnet Calculator such as the ip subnet calculator can be used if required to determine the range of IP Addresses etc.

Gateway Subnet Prefix (External Gateway object)

As part of the addition of the IPv6/IPv4 dual stack functionality, the IP Mask field in the External Gateway object has been replaced with an Allowed Gateway Subnet Prefix. The Gateway Subnet Prefix field was added to the External Gateway object and is used to configure the IMG 2020 to accept either one or a range of IP addresses from a specific external gateway in a network. The value that is entered in the Allowed Gateway Subnet field in conjunction with the IP address entered determines the range of IP addresses from which the IMG 2020 will accept any calls. Refer top the tables below for examples of how Subnet Prefixes are utilized in both IPv4 and IPv6.

Network Prefix Length (IP Address object)

As part of the addition of the IPv6/IPv4 dual stack functionality, the Subnet field in the IP Address object has been replaced with a /Network Prefix Len field. The /Network Prefix Len field was added to the IP Address object and is used to configure the IMG 2020 to accept and process either one or a range of IP addresses that is received at that specific interface. The value that is entered in the Network Prefix Len field in conjunction with the IP address entered determines the range of IP addresses from which the interface being configured will accept and process. Refer top the tables below for examples of how Subnet Prefixes are utilized in both IPv4 and IPv6.

Examples for IPv4 - IP Address/(subnet prefix)

Examples for IPv6 - 9876:fedc:6543:dcba:1234:abcd:4567:1111/(subnet prefix)

IPv4

232- 2x = Number of IP addresses where x=CIDR prefix

Examples:

10.129.20.20/31 = 232- 231 = 21 = 2 addresses

10.129.20.20/28 = 232- 228 = 24 = 14 addresses + Subnet ID Address + Broadcast Address

IPv6

2128- 2x = Number of IP addresses

 IPv6 Basics

The section below gives a basic high level overview of IPv6. It is advisable that if IPv6 needs to be learned, that more detailed resources be utilized.

Architecture of IPv6

The IPv6 format uses addresses that are 128 bits which is 4 times the size of the IPv4 addresses. Below is a representation of an IPv6 address but is being displayed in individual bits. Normal IPv6 addresses uses hexadecimal code. The screen capture below is displayed to describe how the subnet prefix is determined.

Open

The delineation between the Network portion and the Subnet portion in the screen capture above is /64 since there are 64 bits in the subnet portion. The Subnet Prefix in this case is 64. Any length between 8 and 128 is accepted as a subnet prefix when configuring IPv6 on the IMG 2020.

Text Representation and short-hand techniques

The IPv6 is represented in hexadecimal format and is represented by 8 groups of 16 bit values. Each group is represented by 4 hexadecimal digits and separated by a colon. Below is how an IPv6 address would be displayed if no shorthand techniques are employed.

The address above is a very long and cumbersome address to enter. The IMG 2020 conforms to RFC 4291 - IP Addressing Architecture. This RFC describes how to shorten the IPv6 formatted IP address. Below are some techniques described that can be utilized to shorten the address.

Additional Information 

General

• The IMG 2020 supports both IPv4 and IPv6 simultaneously.

• Both IPv4 and IPv6 addresses can be configured on the same Logical Interface configured in the Logical Interface object.

• As described above, when configuring Media IP addresses, only one type of IP format (IPv4/IPv6) can be used per Media IP Address. In other words, if IPv4 was used for the first instance of Media 0, IPv4 must be used for the second instance of Media 0. This is true for IPv6 as well. Refer to the table in the Summary of IPv6 functionality section above.

• As described above, when configuring Media IP addresses, only one type of IP format (IPv4/IPv6) can be used per Media Endpoint (Media 0/Media 1). In other words, if IPv6 was used for the first instance of Media 1, IPv6 must be used for the second instance of Media 1. This is true for IPv6 as well. Refer to the table in the Summary of IPv6 functionality section above.

• The IMG 2020 supports the Neighbor Discovery Protocol via RFC 4861. The IMG 2020 utilizes the Neighbor Discovery Protocol to respond and advertise its link addresses as well as to discover link addresses of destination IP addresses.

• The IMG 2020 now supports interworking messaging from an IPv4 network to an IPv6 network and also supports interworking messaging from an IPv6 network to an IPv4 network.

• RTP Media and Multimedia packets are supported using the IPv6 protocol.

• SIGTRAN or M3UA is not supported using the IPv6 protocol.

• Smart Probing does not support using IPv6 protocol.

• ICMP echo requests can be configured through the GUI to either be allowed or not allowed.

• Duplicate Address Detection as per RFC4862 is supported.

DNS

• IPv6 has been added to support external DNS Servers with IPv6 capabilities.

• The IMG 2020 can be configured to be a DNS Client to an external DNS Server. The IMG 2020 now supports configuring multiple DNS Clients to be able to communicate with one or more external DNS Servers.

• Name Resolution Service supports requesting AAAA records for host names resolved for IPv6 addresses.

• An IPv6 Client that receives only the A Record back from a DNS Server will treat the lookup as unreachable