IPV6 Crib Notes

These are my ‘crib notes’ that I’ve made to serve as a last minute refresher. Please forgive the grammer / spelling as I did not develop these notes with publishing in mind.

IPV6

***theory***

  • Anycast address: assigned to multiple interfaces & delivered to closes host that shares that address
  • (Aggregate able) global unicast address  (001)= IPV4 Public unicast address. Are routable to internet and can be summarised.
  • Multicast (1111 1111 or FF00::/8)
  • Link local (1111 1110 10 or FE80::/10) – Small scope, use to address a physical link (private address)
  • Site Local (1111 1110 11 or FEC0::/10)  – Allows devices in same organisation to exchange data = IPV4 private addresses
  • Loopback test (127.0.0.1) = ::1 OR 0:0:0:0:0:0:0:1
  • Unspecified / unknown address = ::/128
  • Default route =::/0
  • SLA – Site level aggregator – subnet for IPV4
  • IPV4 compatible address  – first 96bit are 0
  • IPV4 vs. IPV6: uses 128 bit address (16 bit hex). IPV4 uses 32 bit address. IPV4 has DHCP. IPV6 has Auto configuration (state and stateless)
    • Stateful – from server
    • Stateless – IPV6 host configures it own link-local. Does this by using FE80::0 followed by it MAC add for interface identifier e.g. FE80:ABCD:1234:5678. Once done, send (NS FF02::1 – all nodes) Neighbour Solicitation message to see if any host has same link local address.  If they do, that host sends a NA Neighbour Advertisement. The original host will then disable it local link address as part of DAD – Duplicate address detection procedure. It then sends a (RS FF01::2 – All routers multicast) Router Solicitation on to the segment once it happy it has a unique local link address.  The router then sends RA Router Advertisement which has additional information for the host to complete auto configuration
    • Header fields: 8 in IPV6
      • Version (set to 6). Traffic class (equivalent to ToS in IPV4), flow label (new. Allows packets in a flow to be marked), payload length (IPV4 equiv is Total Length Field), Hop Limit (equiv to IPV4 TTL field), Next Header (equiv to IPV4 protocol field), SAD & DAD NOW 128 bits!
      • IPV4 not in IPV6: Header Length, Identification, Flags, Fragment Offset, Header Checksum
      • IPV6: Has IPSec built in. IPV6 useful for IP Phones, GPS etc
      • IPV6 addressing (shortening):
        • Zero Compression: can condense consecutive zero with two colons (can only do ONCE). E.g.
          • 1234:1234:0000:0000:0000:0000:3456:3434
          • 1234:1234::3456:3434
  • Leading zeros can be compressed E.G.
    • 1234:0000:1234:0000:1234:0000:0123:1234
    • 1234:0:1234:0:1234:0:123:1234
  • Use both E.g.
    • 1111:0000:0000:1234:0011:0022:0033:0044
    • 1111::1234:11:22:33:44
    • IPV6 address convert to IPV4
      • ::D190:4E71
      • D1 = 13 X 16 + 1 x 1 = 209. 90 = 9 x 16 + 0 x 1 = 144. 4E = 4 x 16 + 14 x 1 = 78. 71 = 7 x 16 + 1 x 1 = 113 = 209.144.78.113
      • OPSF V3 – enabled on interface (unlike v4, enabled on router). Uses IPV4 address as it RID
      • MIGRATE IPV4 – IPV6
        • Dual Stack: Runs both IPV4 & IPV6 on an interface
        • 6to4 tunnel: automatic, session torn down when it ends & scalable. IPV6 encapsulated in IPV4 packet (protocol 41) through core. Uses 2002 + router IP address in hex. E.g. 2002:1234:83cd::/48
        • NAT PT

***commands***

  • R1 (Config)# IPV6 unicast-routing

Enables IPV6 on a router

  • R1(Config-if)# ipv6 ospf area 0
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