IPv6

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IPv6

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IP version 6 (IPv6) was developed to overcome the limitations of the current standard, IP version 4 (IPv4). IPv4 allows end systems to communicate and forms the foundation of the Internet as we know it today. However, one of the major shortcomings of IPv4 is its limited amount of address space. The explosion of new IP-enabled devices and the growth of undeveloped regions have fueled the need for more addresses.

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Nội dung Text: IPv6

IPv6 CCNA Exploration version 4.0
Overview • IP version 6 (IPv6) was developed to overcome the limitations of the current standard, IP version 4 (IPv4). IPv4 allows end systems to communicate and forms the foundation of the Internet as we know it today. However, one of the major shortcomings of IPv4 is its limited amount of address space. The explosion of new IP-enabled devices and the growth of undeveloped regions have fueled the need for more addresses. • In the United States, the Department of Defense (DoD) is a primary driver for the adoption of IPv6. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 2
Introducing IPv6 • IP version 6 (IPv6) combines expanded addressing with a more efficient and feature-rich header to meet the demands for scalable networks in the future. • One key benefit is that IPv6 can recreate end-to-end communications without the need for Network Address Translation (NAT) • Cisco Systems currently supports IPv6 in Cisco IOS Software Release 12.2(2)T and later. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 3
IPv6 Features Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 4
Large Address Space Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 5
• IPv6 routers do not perform fragmentation. Instead, a discovery process determines the optimum maximum transmission unit (MTU) to use during a given session. • Link-layer technologies already perform checksum and error control. Because link-layer technologies are relatively reliable, an IP header checksum is considered to be redundant. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 6
Comparing IPv4 and IPv6 Headers Traffic class: ToS Payload Length Next Header: Tcp, Udp… Hop Limit: TTL No Checksum • Flow Label: 20-bit field that allows a particular flow of traffic to be labeled. It can be used for multilayer switching techniques and faster packet-switching performance. • Extension Headers: Follows the previous eight fields. The number of extension headers is not fixed, so the total length of the extension header chain is variable. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 7
Extension Header Extension Header Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 8
IPv6 Extension Headers • IPv6 Header: Basic header described in the previous figure. • Hop-by-hop options header • Destination options header (when the routing header is used) • Routing header: Used for source routing and mobile IPv6 (value = 43). • Fragment header: Used when a source must fragment a packet that is larger than the MTU for the path between itself and a destination device. • Authentication header and Encapsulating Security Payload header: Used within IPsec to provide authentication, integrity, and confidentiality of a packet. The authentication header (value = 51) and the ESP header (value = 50) • Upper-layer header: Typical headers used inside a packet to transport the data. The two main transport protocols are TCP (value = 6) and UDP (value = 17). Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 9
Defining Address Representation • Leading zeros in a field are optional, so 09C0 = 9C0 and 0000 = 0. • Successive fields of zeros can be represented as “::” only once in an address. • An unspecified address is written as “::” because it contains only zeros. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 10
IPv6 Address types • Unicast address – Link local: FE80::/10, Scope is configured to single link. The address is unique only on this link, and it is not routable off the link. (similar to 169.254.x.x private address) – Site local: FEC0::/10 (similar to private address) – Global: Globally unique, so it can be routed globally with no modification. A global address has an unlimited scope on the worldwide Internet. Packets with global source and destination addresses are routed to their target destination by the routers on the Internet. • Multicast address: IPv6 does not have broadcast addresses. The range of multicast addresses in IPv6 is larger than in IPv4. For the foreseeable future, allocation of multicast groups is not being limited. • Anycast address: An anycast address identifies a list of devices or nodes; therefore, an anycast address identifies multiple interfaces. A packet sent to an anycast address is delivered to the closest interface, as defined by the routing protocols in use. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 11
Special Address Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 12
IPv6 Global Unicast and Anycast address • Global unicast addresses are defined by a global routing prefix, a subnet ID, and an interface ID. The current global unicast address assignment by the Internet Assigned Numbers Authority (IANA) uses the range of addresses that start with binary value 001 (2000::/3), which is one-eighth of the total IPv6 address space and is the largest block of assigned block addresses. • Addresses with a prefix of 2000::/3 (001) through E000::/3 (111), with the exception of the FF00::/8 (1111 1111) multicast addresses, are required to have 64-bit interface identifiers in the extended universal identifier (EUI)-64 format. • When a unicast address is assigned to more than one interface, thus turning it into an anycast address, the nodes to which the address is assigned must be explicitly configured to use and recognize the anycast address. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 13
IPv6 Global Unicast and Anycast address Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 14
Defining Host Interface Addresses • An IPv6 address has two parts: – A subnet prefix representing the network to which the interface is connected. The subnet prefix is a fixed 64-bit length for all current definitions. – A local identifier, sometimes called a token, which uniquely identifies the host on the local network. The local identifier is always 64 bits and is dynamically created based on Layer 2 media and encapsulation. In the simple case of an Ethernet medium, the local identifier is usually derived from the EUI-48 MAC address. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 15
Link Local Address • The address is unique only on this link, and it is not routable off the link. Packets with a link-local destination must stay on the link where they were generated • Link-local addresses are dynamically created using a link- local prefix of FE80::/10 and a 64-bit interface identifier in a process called stateless autoconfiguration. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 16
Stateless Autoconfiguration • Phase 1: MAC 00-0C-29-C2-52-FF -> 00-0C-29-FF-FE-C2- 52-FF • Phase 2: well-known link-local prefix fe80::/64 is added -> fe80::00c:29ff:fec2:52ff • Phase 3: Verify the address’s uniqueness on the link, called duplicate address detection (DAD). Send ICMPv6. • Phase 4: Assigned Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 17
IPv6 Multicast Address Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 18
IPv6 Multicast Address • FF02::1:FFXX:XXXX — Solicited-node multicast on link, where XX:XXXX is the rightmost 24 bits of the corresponding unicast or anycast address of the node. (Neighbor solicitation messages are sent on a local link when a node wants to determine the link-layer address of another node on the same local link, similar to Address Resolution Protocol [ARP] in IPv4.) Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 19
IPv6 Routing • Similar to IP version 4 (IPv4) classless inter-domain routing (CIDR), IPv6 uses longest-prefix match routing. • Routing protocol: RIPng, OSPFv3, EIGRP, ISIS, MP-BGP • Static routing: A router must be able to determine the link- local address of each of its neighboring routers to ensure that the target address of a redirect message identifies the neighbor router by its link-local address. Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 20

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