CDN systems can bring the content source closer to the costumers take the advantages of the distributed architecture. Thus service providers can reduce the traffic load on their core network. Nowadays the number of the allocatable public IPv4 address ranges has fallen below the critical level. Hence in the planning and development of IP networks the IPv6 protocol has become a significant factor. Using IPv6 guarantees the opportunity of connecting to the Internet using public addresses for numerous costumer (even household) devices. The most recognizable difference between IPv4 and IPv6 is the address space. An IPv4 address is 32 bits and expressed in dotted-decimal notation, whereas an IPv6 address is 128 bits in length and written in hexadecimal. IPv6 addressing is defined in RFC 4291, IP Version 6 Addressing Architecture. ICMP is one of the core protocols of the TCP/IP suite of protocols. It is employed by operating systems to send messages between devices. The types of messages can be either informational and/or error messages such as an Echo Request for a ping command or informing the sender that the router was unable to forward the packet. ICMP is used with applications such a ping and traceroute to test network connectivity between two devices.ICMPv6 is described in RFC 4443, Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification. ICMPv6 is much more robust than ICMPv4, containing new functionality and improvements.