INE R&S ATC112 ~ ATC118 - IPv6

IPv6 Overview
• RFC 2460 “Internet Protocol, Version 6 (IPv6) Specification”
• Much larger address space than IPv4
– IPv4 uses 4 Byte (32 Bit) Addresses
• 232= 4,294,967,296 addresses
– IPv6 uses 16 Byte (128 Bit) Addresses
• 2128~ 340 undecillion(3.4×1038)

IPv4 vs. IPv6 Addressing Format
• IPv4 Dotted Decimal
– d.d.d.d
– d = one byte
• IPv6 Hexadecimal
– hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh
– hh= one byte

RFC 4291: IPv6 Addressing
2.4. Address Type Identification
The type of an IPv6 address is identified by the high-order bits ofthe address, as follows:
Address type        Binary prefix     IPv6 notation Section
---------------------------------------------------------------
Unspecified         00...0 (128 bits) ::/128        2.5.2
Loopback            00...1 (128 bits) ::1/128       2.5.3
Multicast           11111111          FF00::/8      2.7
Link-Local unicast  1111111010        FE80::/10     2.5.6
Global Unicast      (everything else)

IPv6 Link Local Addresses
• Addresseslocally significant to a link
– FE80::/10 (1111 1110 10)
– RFC 4291 “IP Version 6 Addressing Architecture”
• Never routable between interfaces
• Used for…
– Stateless Address Autoconfiguration
– Neighbor Discovery
– Router Discovery
 
IPv6 Site Local Addresses
• Addresses locally significant to a “site”
– FEC0::/10 (1111 1110 11)
– RFC 1884 “IP Version 6 Addressing Architecture”
• No one could agree on what a “site” is
– RFC 3879 "Deprecating Site Local Addresses“

IPv6 Unique Local Addresses
• ULA is Private Use IPv6 addressing
– FC00::/7 (1111 110)
– RFC 4193 “Unique Local IPv6 Unicast Addresses”
• Equivalent to RFC 1918
– 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
• Likely unique but not routable via global BGP

IPv6 Global Unicast Addresses
• Technicallyeverything else
– IANA currently allocating 2000::/3
• PerRFC end hosts must…
– Have 64-bit interface ID
• nnnn:nnnn:nnnn:nnnn:hhhh:hhhh:hhhh:hhhh/64
– Use EUI-64 format for interface ID

Modified EUI-64 Addressing
• RFC 4291 “IP Version 6 Addressing Architecture”
– Appendix A: Creating Modified EUI-64 Format Interface Identifiers
• Ethernet MAC to EUI-64 conversion
– Invert Universal/Local (U/L) bit
• 7thmost significant bit
– Insert padding 0xFF 0xFE in the middle

IPv6 Address Resolution
• RFC 4861 “Neighbor Discovery for IP version 6 (IPv6)”
– ICMPv6 ND used for layer 3 to layer 2 resolution
• Ethernet
– ICMPv6 ND replaces ARP
• NBMA
– Inverse ND
• RFC 3122 "Extensions to IPv6 Neighbor Discovery for Inverse Discovery"
– Static layer 3 to layer 2 mappings

IPv6 Routing Overview
• IPv6 routing off by default
– ipv6 unicast-routing
– Enables routing and ICMPv6 ND RAs
• IPv6 routing is supported by all protocols
– Static, RIPng, EIGRPv6, OSPFv3, IS-IS, MP-BGP, & Policy Routing
• Dynamically learned routes recurse to remote link-local address
– Implies Global Unicast isn’t required
– Implies static layer 3 to layer 2 resolution for Link Local is needed on multipoint NBMA

IPv6 Static Routing
• Same static routing implications as IPv4
– Routing to a next-hop
• Resolve layer 2 address of next-hop
– Routing to a multipoint interface
• Resolve layer 2 addressof final destination
• Proxy ND and Proxy IND design issues
– Routing to a point-to-point interface
• No layer 2 resolution required

RIPng Overview
• RFC 2080 “RIPngfor IPv6”
• Similar in operation to RIPv2
– Transport via UDP port 521 to multicast FF02::9
• Enabledat link level
– ipv6 rip [process-id] enable
– Automatically enables global process
• Split-horizon enabled at process level
– Disabled via process level no split-horizon

EIGRPv6 Overview
• Similar in operation to EIGRP
– Transport via protocol 88 to unicast and multicast FF02::A
• Enabled at link level
– ipv6 eigrp[ASN]
• Global process disabled by default
– no shutdownunder global process
– IPv4formatted Router-ID needed
 
OSPFv3 Overview
• RFC5340 “OSPF for IPv6”
• Similar in operation to OSPFv2
– Transport via protocol 89 to unicast and multicasts FF02::5 & FF02::6
• Enabled at link level
– ipv6 ospf[process-id] area [area-id]
– Automatically enables global process
• Normal OSPF rules still apply
– Adjacency parameters
– OSPFv3 network types
– IPv4 formatted Router-ID needed
 
BGP for IPv6 Overview
• RFC 2545 “Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing”
• Transport and NLRI are independent
– Transport can be IPv4 or IPv6
– NLRI advertised via AFI 2 SAFI 1
• address-family ipv6 unicast
• Normal BGP rules apply
– Requires underlying IGP for TCP transport
– EBGP loop prevention via AS-Path
– iBGP loop prevention via full mesh, RRs, Confederation
– Same attributes and best-path selection process

IPv6 Tunneling
• IPv6 can be transport or payload of a tunnel
– IPv6 over IPv4 GRE tunnel
– IPv6 over IPv6IP tunnel
– IPv6 over IPv4 UDP TeredoTunnel
– IPv4 over IPv6 GRE tunnel

IPv6 over IPv4 Tunnels
• Statictunnels
– GRE
• Default tunnel mode
– IPv6IP
• Less overhead but no CLNS transport
• Automatic tunnels
– 6to4
• Inter-Site tunneling
• Imbeds IPv4 address into IPv6 prefix to provide automatic tunnel endpoint determination
– ISATAP
• Intra-Site Automatic Tunnel Addressing Protocol
• Automatic host to router and host to host tunneling

Automatic 6to4 Tunneling
• Derives destination IPv4 router from address imbedded inside IPv6 destination
– 2002:border-router-IPv4-address::/48
• Single /48 subnettedamongst site
• Only one tunnel needed for all destinations