ICMPv4 vs ICMPv6 | Ping Traceroute to Verify Network Connectivity

ICMPv4 and ICMPv6 | Ping Traceroute to Verify Network Connectivity 

This article is about how to use ICMP (Internet Control Message Protocol), ICMPv4 and ICMPv6 and the ping and traceroute utilities to Verify network connectivity.

ICMPV4 Vs ICMPV6

Although IP is only a maximum effort protocol, the TCP / IP packet allows messages to be sent in case of certain errors. These messages are sent through the ICMP services . The purpose of these messages is to provide answers about issues related to the processing of IP packets under certain conditions, it is not to make IP reliable. ICMP messages are not mandatory and are often not allowed within a network for security reasons. The ICMP protocol is available for both IPv4 and IPv6 and includes the following messages:

• Host confirmation : An ICMP echo message can be used to determine if a host works.
• Destination or service inaccessible : When a host or gateway receives a packet it cannot deliver, it can use an ICMP message of unreachable destination to notify the source that the destination or service is unreachable. (0: unreachable network, 1: unreachable host, 2: unreachable protocol, 3: unreachable port)

ICMPv6 has similar, but slightly different codes for unreachable destination messages.

• Timeout : Routers use ICMPv4 timeout messages to indicate that a packet cannot be forwarded because the packet's duration time (TTL) field was decreased to 0.

ICMPv6 also sends a timeout message if the router cannot resend an IPv6 packet because the packet expired. IPv6 does not have a TTL field, so it uses the hop limit field to determine if the packet expired.

• Route redirection

ICMPv6 Router Request and Announcement message

The information and error messages found in ICMPv6 are very similar to the control and error messages implemented by ICMPv4. However, ICMPv6 has new features and enhanced functionality that are not found in ICMPv4. ICMPv6 messages are encapsulated in IPv6.

ICMPv6 includes four new protocols as part of the Neighbor Discovery Protocol (ND or NDP) (Neighbor Discovery Protocol).

Messaging between an IPv6 router and an IPv6 device:  sent between hosts and routers.

• Router request (RS) message: sent as an IPv6 multicast message from all routers.
• Router Announcement (RA) Message: Routers send RA messages to provide routing information.

Messaging between IPv6 devices:  They are used for address resolution and for duplicate address detection (DAD).

• Neighbor Request (NS) Message: Sent when a device knows the IPv6 address of another device, but not the MAC address. (Equivalent to an ARP request for IPv4)
• Neighbor announcement message (NA)

PING

Ping is a test utility that uses ICMP echo request and response messages to test connectivity between hosts. Ping works with IPv4 and IPv6 hosts. A response of 127.0.0.1 for IPv4 (or :: 1 for IPv6) indicates that IP is installed correctly on the host.

Ping Traceroute to Verify Network Connectivity 

• Testing the connectivity to the local LAN : It is possible to use the ping command to test the communication capability of a host on the local network. Usually, this is done by pinging the IP address of the host gateway.
• Testing the connectivity to a remote network : You can use the ping command to test the ability of a local host to communicate in a network interconnection. The local host can ping an operational IPv4 host on a remote network.

TRACEROUTE: ROUTE TEST

It is a utility that generates a list of jumps that were successfully reached along the route.

In summary, the tracert command :

• It generates a list of jumps that were successfully reached along the route.
• Provides important information for verification and problem solving purposes.
• If the data reaches the destination, the trace indicates the interface of each router that appears in the route between the hosts.
• If there is an error in the data in any jump along the way, the address of the last router that responded to the trace may indicate where the problem is or security restrictions.
• It provides the round trip times for each jump along the route and indicates if a jump does not respond.
• The Router discards the packet when the value in the TTL field reaches zero