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BAI513 - Protocols

BAIST – Network Management. BAI513 - Protocols. IP Version 6 Protocol Structure & Addressing. IPv6 – Why. Internet Growth and Routing Tables Even though IPv4 supports about 4 billion IP addresses, the IETF predicted in 1990 that these addresses would be exhausted in 10 years.

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BAI513 - Protocols

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  1. BAIST – Network Management BAI513 - Protocols IP Version 6 Protocol Structure & Addressing

  2. IPv6 – Why • Internet Growth and Routing Tables • Even though IPv4 supports about 4 billion IP addresses, the IETF predicted in 1990 that these addresses would be exhausted in 10 years. • NAT/PAT and Public/Private Addressing (RFC 1918) were seen as only temporary fixes.

  3. IPv6 - History • IPv5 was defined as an Internet Stream Protocol that was to provide QoSRFC 1190 - October, 1990 • Expermental Resourse Reservation Protocol that used the same link-layer framing as IPv4 • IPv6 Originated from RFC 1752 – IPng • First IPv6 spec appeared in RFC 1883 (1995) • RFC 2460 – Internet Protocol Version 6 (IPv6) Specifications (1998), obsoletes RFC 1883

  4. IPv6 - What’s changed ? • Expanded Address Space • Address lengthquadrupled to 128-bit addresses • (340,282,366,920,938,463,463,374,607,431,768,211,456 in all!) • Header Format Simplification • Fixed length, optional headers are daisy-chained • IPv6 header is twice as long (40 bytes) asIPv4 header without options (20 bytes) • No checksumming at the IP network layer • No hop-by-hop segmentation • Path MTU discovery • 64 bits aligned • Authentication and Privacy Capabilities • IPsec is mandated • No more broadcasts

  5. IPv4 & IPv6 Header Comparison IPv6 Header IPv4 Header - field’s name kept from IPv4 to IPv6 - fields not kept in IPv6 - Name & position changed in IPv6 - New field in IPv6

  6. IPv6 Header Next Header = Routing IPv6 Header Next Header = TCP IPv6 Header Next Header = Routing Routing Header Next Header = TCP Fragment Header Next Header = TCP TCP Header + Data TCP Header + Data Routing Header Next Header = Fragment Fragment of TCP Header + Data IPv6 Header Options RFC 2460 • Processed only by node identified in IPv6 Destination Address field => much lower overhead than IPv4 options exception: Hop-by-Hop Options header • Eliminated IPv4’s 40-octet limit on options in IPv6, limit is total packet size, or Path MTU in some cases

  7. Hop-by-Hop Options Header Next Header Hdr Ext Len • Used to carry optional information that must be examined by every node alon a packet’s delivery path. • If used, must immediately follow IPv6 header. • Only options defined to date are Padding Options

  8. Routing Header Next Header Hdr Ext Len Routing Type Segments Left • Used by an IPv6 source to list intermediate nodes to be visited – similar to IPv4 Loose Source and Record Route option. • Only Routing Type 0 is defined (RFC 2460). • Only processed by node identified by the destination address in IPv6 header. • Type-Specific Data identifies next destination address to send data Type-Specific Data

  9. Fragment Header Next Header Reserved Fragment Offset Res M • Packets that are too large for the path MTU are fragmented by the source (not the router as with IPv4). • The source then creates the fragment header as above. Identification

  10. Destinations Options Header Next Header Hdr Ext Len • Used to carry optional information that needs to be examined by the destination node(s). • The only destination options defined to date are Padding. Options

  11. IPv6 Header Options RFC 2460 • Currently defined Headers should appear in the following order • IPv6 header • Hop-by-Hop Options header (value = 0) • Destination Options header (value = 60) • Routing header (value = 43) • Fragment header (value = 44) • Authentication header (value = 50) • Encapsulating Security Payload (value = 51) • Destination Options header (value = 60) • upper-layer header – usually TCP (6) or UDP (17) • NOTE: no next header identifeid by value = 59

  12. IPv6 Addressing • 128-bit addresses • (340,282,366,920,938,463,463,374,607,431,768,211,456 in all!) • IPv6 Addressing rules are covered by multiples RFC’s • Architecture defined by RFC 3513 (obsoletes RFC 2373) • Address Types are : • Unicast : One to One (Global, Link local, Site local, IPv4 Compatible) • Anycast : One to Nearest (Allocated from Unicast) • Multicast : One to Many • No Broadcast Address -> Use Multicast • A single interface may be assigned multiple IPv6 addresses of any type (unicast, anycast, multicast)

  13. IPv6 Address Representation • 16-bit fields in case insensitive colon hexadecimal representation • 2001:0000:130F:0000:0000:09C0:876A:130B • Leading zeros in a field are optional: • 2001:0:130F:0:0:9C0:876A:130B • Successive fields of 0 represented as ::, but only once in an address: • 2001:0:130F::9C0:876A:130B • 2001::130F::9C0:876A:130B NOT ALLOWED • 0:0:0:0:0:0:0:1 => ::1 • 0:0:0:0:0:0:0:0 => ::

  14. Global Unicast Addresses Provider Site Host 3 45 bits 16 bits 64 bits • Aggregatable Global Unicast addresses are: • Addresses for generic use of IPv6 • Structured as a hierarchy to keep the aggregation • See RFC 3513 Global Routing Prefix SLA Interface ID 001

  15. Link-Local Unicast Address 64 bits • Link-local addresses for use during auto-configuration and when no routers are present: 1111111010 0 Interface ID 10 bits FE80:: /10

  16. Site-Local Unicast Address 64 bits • Site-local addresses for independence from Global Reachability, similar to IPv4 private address space 1111111011 0 Interface ID 10 bits FEC0:: /10 16 bits Subnet ID

  17. Interface ID’s • Lowest-order 64-bit field of unicast address may be assigned in several different ways: • auto-configured from a 64-bit EUI-64, or expanded from a 48-bit MAC address (e.g., Ethernet address) • auto-generated pseudo-random number(to address privacy concerns) • assigned via DHCP • manually configured

  18. IPv4-Compatible IPv6 Address 32 bits 96 bits • It is a type of IPv6 unicast address that embeds an IPv4 address in the low-order 32 bits and zeros in the high-order 96 bits of the IPv6 address. • Used in IPv6 transition mechanisms to tunnel IPv6 packets dynamically over IPv4 infrastructures. 0 IPv4 Address 0:0:0:0:0:0 192.168.30.1 IPv4-Compatible Address = 0:0:0:0:0:0:C0A8:1E01

  19. IPv4-Mapped IPv6 Address 16 bits 32 bits 80 bits • Another type of IPv6 unicast address that is used to represent the address of an IPv4 node as an IPv6 address. • An IPv6 application sending traffic to this address will send IPv4 packets to the destination node. 0 FFFF IPv4 Address 0:0:0:0:0 192.168.30.1 IPv4-Mapped Address = 0:0:0:0:0:FFFF:C0A8:1E01

  20. IPv6 Anycast Address • Global unicast address that is assigned to a set of interfaces that typically belong to different nodes. • A packet sent to an anycast address is delivered to the closest interface. • Anycast addresses must not be used as the source address of an IPv6 packet. • No real use for anycast addresses yet, but they may be used by IPv6 routers

  21. IPv6 Multicast Addresses 128 bits • Multicast is used in the context of one-to-many, same as IPv4. 0 Group ID T=0 a permanent IPv6 Multicast address. T=1 a transient IPv6 multicast address 1111 1111 Flags Flags = F F scope 0 0 0 0 T 1 = node 2 = link 5 = site 8 = organization E= global 8 bits 8 bits Scope =

  22. Multicast Address Assignments • FF01::1 – All Nodes within the node-local scope • FF02::1 – All nodes on the local link • FF01::2 – All Routers within the node-local scope • FF02::2 – All Routers on the link-local scope • FF05::2 – All Routers in the site. • FF02::1:FFXX:XXXX – Solicited Node multicast address, where xx:xxxx represents the last 24 bits of the IPv6 node address. • Solicited Node Multicast Addresses are used in neighbor solicitation messages (covered later).

  23. Multicast Listener Discover – MLD • MLD is equivalent to IGMP in IPv4 • MLD messages are transported over ICMPv6 • Version number confusion: • MLDv1 corresponds to IGMPv2 • RFC 2710 • MLDv2 corresponds to IGMPv3, needed for SSM • draft-vida-mld-v2-06.txt • MLD snooping • draft-ietf-magma-snoop-04.txt

  24. IPv4 versus IPv6 Multicast IP Service IPv4 Solution IPv6 Solution Address Range 128-bit 32-bit, class D Protocol Independent All IGPs,and BGP4+ with v6 mcast SAFI Protocol Independent All IGPs,and BGP4+ Routing PIM-DM, PIM-SM, PIM-SSM, PIM-bidir PIM-SM, PIM-SSM, PIM-bidir Forwarding MLDv1, v2 Group Management IGMPv1, v2, v3

  25. IPv6 Host Address Requirements • Link-local address for each interface • Assigned unicast address(es) • Loopback address • All-nodes multicast address • Solicited-node multicast address for each of its assigned unicast and anycast addresses • Multicast addresses of all other groups to which the host belongs • Site-local address, if used

  26. IPv6 Host Address Example Ethernet0 interface Ethernet0 ipv6 address 2001:400:213:1::/64 eui-64 MAC address: 0060.3e47.1530 router# show ipv6 interface Ethernet0 Ethernet0 is up, line protocol is up IPv6 is enabled, link-local address is FE80::260:3EFF:FE47:1530 Global unicast address(es): 2001:400:213:1:260:3EFF:FE47:1530, subnet is 2001:400:213:1::/64 Joined group address(es): FF02::1:FF47:1530 FF02::1 FF02::2 MTU is 1500 bytes

  27. IPv6 Address Allocation Policy /48 /64 /23 /32 • The allocation process is under review by the Registries: • IANA allocates 2001::/16 to registries • Each registry gets a /23 prefix from IANA • With the new policy, Registry allocates a /32 prefix to an IPv6 ISP • Then the ISP allocates a /48 prefix to each customer (or potentially /64) 2001 Interface ID Registry ISP prefix Site prefix Bootstrap process - RFC2450 LAN prefix

  28. Registry Allocated Addresses • 2001:0200::/23 and 2001:0C00/23 allocated to APNIC for use in Asia • 2001:0400::/23 allocated to ARIN for use in the Americas • 2001:0600::/23 and 2001:0800::/23 allocated to RIPE NCC for use in Europe and Middle East

  29. ISP 2001:0400::/32 Customerno 2 Customerno 1 IPv6 Internet 2001::/16 Hierarchical Addressing & Aggregation Only announces the /32 prefix • Address Allocation Policy enables: • Aggregation of prefixes announced in the global routing table. • Efficient and scalable routing. 2001:0400:0001:/48 2001:0400:0002:/48

  30. 6BONE • The 6bone is an IPv6 testbed setup to assist in the evolution and deployment of IPv6 in the Internet. • The 6bone is a virtual network layered on top of portions of the physical IPv4-based Internet to support routing of IPv6 packets, as that function has not yet been integrated into many production routers. The network is composed of islands that can directly support IPv6 packets, linked by virtual point-to-point links called "tunnels". The tunnel endpoints are typically workstation-class machines having operating system support for Ipv6. • Over 50 countries are currently involved • Registry, maps and other information may be found on http://www.6bone.net/

  31. 6Bone Addressing /28 /48 /64 • 6Bone address space defined in RFC2471 uses 3FFE::/16 • A pTLA receives a /28 prefix • A site receives a /48 prefix • A LAN receives a /64 prefix • Guidelines for routing on 6bone - RFC2772 Interface ID 3ffe pTLA prefix site prefix LAN prefix

  32. pTLA pTLA pTLA pTLA pTLA pTLA pTLA Provider Provider Site Site Site Site Site Site Site Site Site Site 6Bone Topology BGP Peering • 6Bone is a test bed network with hundreds of sites from 50 countries • The 6Bone topology is a hierarchy of providers • First-level nodes are backbone nodes called pseudo Top-Level Aggregator (pTLA)

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