Quality of Service and performance characterization of IPv6 relative to IPv4

II.6 IPv6 CONNECTIVITY

The ping (Packet Internet Groper) command: The command is used with the IP address of the destination device. The command can be utilized as shown in Figure using the IP address of the destination device. In these examples, the ping command issues four echo requests and receives four echo replies, confirming IP connectivity between the two devices.^25(*)

The following command of ping6 is shown below:

· To ping the global address of another node:

ping6 Address

where Address is the global address of the other node.

If the ping6 command fails, verify the global address of the other node.

· To ping another node by name:

ping6 Name

where Name is a name that can be resolved to an IPv6 address through entries in the local hosts file, or through AAAA resource records that are present in your Domain Name System (DNS) infrastructure.

If the ping6 command fails, verify that the name can be resolved to an IPv6 address.

· To ping the IPv4-compatible address of another node:

ping6 ::IPv4Address

where IPv4Address is the IPv4 address of the other node.

If the ping6 command fails, verify the IPv4 address of the other node.

· ping the loopback address by typing ping6 ::1.

If the ping6 command fails, verify that the ::1 address is assigned to the interface named Loopback Pseudo-Interface.^26(*)

II.7 ICMP

The Internet Control Message Protocol (ICMP) is an integral part of the TCP/IP protocol suite. It is known as a best effort delivery mechanism. In fact, all IP implementations must include ICMP support. The reasons for this are simple. First, since IP does not guarantee delivery, it has no inherent method to inform hosts when errors occur. Also, IP has no built-in method to provide informational or control messages to hosts. ICMP performs these functions for IP.^27(*)

ICMP is an error reporting protocol for IP. When datagram delivery errors occur, ICMP is used to report these errors back to the source of the datagram.

ICMP reports on the status of the delivered packet only to the source device. It does not propagate information about network changes to routers. The ICMP protocol can be used to test the availability of a particular destination.

II.7.1 ICMPv6

The ICMP for IPv6 (Internet Control Message Protocol Version 6) is an integral part of the IPv6 and must be completely supported by all IPv6 implementations. ICMPv6 works with IPv6. It reports errors if packets cannot be processed properly and sends informational messages about the status of the network.

ICMPv6 is much more powerful than ICMPv4 and contains new functionality, It combines functions previously subdivided among different protocols, such as ICMP (Internet Control Message Protocol version 4), IGMP (Internet Group Membership Protocol)4, and ARP (Address Resolution Protocol), and it introduces some simplifications by eliminating obsolete types of messages no longer in use.

It is used by IPv6 nodes to report errors encountered in processing packets, and to perform other Internet-layer functions, such as diagnostics (ICMPv6 "ping"). ICMPv6 is an integral part of IPv6 and must be fully implemented.^28(*)

* ²⁵ Reference: Cisco Networking Academy Program 2

* ²⁶ http://technet2.microsoft.com/WindowsServer/en/library/c3541ba8-bf24-4298-93b8-7193ba8413b01033.mspx?mfr=true (October 02, 2006)

* ²⁷ Reference: Cisco Networking Academy Program 2, Module 8

* ²⁸ http://en.wikipedia.org/wiki/ICMPv6 (May 22, 2006)