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cisco ccna buy.23.3.2 ICMPv6Like ICMP in IPv4, ICMPv6 is used to help perform diagnostic tests and indicate problems (sendback, sendback reply, destination unreachable, hop limit exceeded, etc.), but with many new features.In a sense, ICMPv6 is like the "Swiss Army Knife" of IPv6 protocols, taking on the responsibilities of the following separate protocols in IPv4.. Address Resolution Protocol (ARP): IPv4 uses ARP to resolve IP addresses into MAC addresses. ARP is no longer included in IPv6 as a standalone protocol, and its functions are performed by ICMPv6.. Internet Group Management Protocol (IGMP): IPv4 uses this protocol to enable routing devices to learn whether there are multicast devices in the VLAN that want to receive multicast streams and forward the corresponding multicast streams to the VLANOIGMP is no longer included as a standalone protocol in IPv6 and its function is performed by ICMPv6.ICMPv6 takes over the responsibilities of other protocols and also provides some new features. Here are some of the new features implemented by ICMPv6. . Router request and announcement: enables devices to query routing devices on a segment using multicast messages and enables routing devices to announce themselves using multicast messages; it also redirects endpoints to the best gateway to the destination network.. DNS requests and announcements: enables the device to query DNS servers on the segment using multicast messages and enables DNS servers to announce themselves using multicast messages.. Neighbor request and announcement: often referred to as neighbor discovery, it uses multicast messages to learn the data link layer protocols of neighbors on the current link (replacing ARP in IPv4), discover neighboring routers, and track the reachability of neighbors.Chapter 23 IPv6 619Exam Points Note that many of the above communications (such as ARP) are done using broadcasts in IPv4, whereas ICMPv6 uses multicasts and unicasts to accomplish them (IPv6 does not support broadcasts).