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21 - Day 32 - IPv6 Part 2.md

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Day 32 - IPv6 Part 2

Reviewed: No

1. Introduction to IPv6 Address Types:

  • Focus on Exam Topics:
    • 1.9: IPv6 address types (Global unicast, unique local, link local, multicast, anycast, etc.).
    • 1.9.f: Understanding and configuring IPv6 using EUI-64.

2. EUI-64 Address Configuration:

  • EUI-64 Overview:
    • EUI-64 stands for Extended Unique Identifier.
    • Converts a 48-bit MAC address into a 64-bit interface identifier.
    • The interface identifier forms the host portion of a /64 IPv6 address.
  • Steps to Convert MAC Address to EUI-64:
    1. Divide the MAC address into two halves.
      • Example: MAC 1234 5678 90AB, split between 56 and 78.
    2. Insert FFFE in the middle.
      • Example: 1234 56FF FE78 90AB.
    3. Invert the 7th bit of the MAC address.
      • The 7th bit is the 3rd bit of the second hex digit.
      • If it’s 0, change it to 1; if 1, change it to 0.
    4. Form the 64-bit Interface Identifier by appending it to the network prefix.
  • Command to Configure EUI-64 on a Cisco Router: ipv6 address [prefix]/64 eui-64
    • Automatically generates the interface ID using EUI-64.

3. IPv6 Address Types:

  1. Global Unicast Addresses:
    • Public addresses used over the Internet.
    • Prefix: Originally 2000::/3, now includes all non-reserved addresses.
    • Structure:
      1. Global Routing Prefix (48 bits): Assigned by ISP.
      2. Subnet Identifier (16 bits): Used to create subnets.
      3. Interface Identifier (64 bits): Can be manually set or generated via EUI-64.
  2. Unique Local Addresses:
    • Private addresses not routable on the Internet.
    • Prefix: FC00::/7 (usually starts with FD).
    • Structure:
      1. FD: Indicates a unique local address.
      2. Global ID (40 bits): Should be randomly generated for uniqueness.
      3. Subnet Identifier (16 bits).
      4. Interface Identifier (64 bits).
  3. Link-Local Addresses:
    • Automatically generated on IPv6-enabled interfaces using EUI-64.
    • Prefix: FE80::/10.
    • Used for communication within a single subnet.
    • Example Uses: Routing protocol peerings, neighbor discovery protocol (NDP), and next-hop addresses for static routes.
  4. Multicast Addresses:
    • Used for one-to-many communication.
    • Prefix: FF00::/8.
    • Important Multicast Addresses:
      • FF02::1: All nodes (acts like a broadcast).
      • FF02::2: All routers.
      • FF02::5: All OSPF routers.
      • FF02::A: All EIGRP routers.
    • Multicast Scopes:
      • FF01::/16: Interface-local (node-local) multicast.
      • FF02::/16: Link-local multicast.
      • FF05::/16: Site-local multicast.
      • FF08::/16: Organization-local multicast.
      • FF0E::/16: Global multicast.
  5. Anycast Addresses:
    • One-to-one-of-many communication.
    • Multiple devices share the same anycast address; the routing protocol forwards packets to the nearest device.
    • Configured like a regular IPv6 address but designated as anycast.
    • Example configuration: ipv6 address [address]/128 anycast
  6. Other IPv6 Addresses:
    • Unspecified Address (::/128): Equivalent to 0.0.0.0 in IPv4, used when a device doesn't know its IPv6 address.
    • Loopback Address (::1/128): Equivalent to 127.0.0.1 in IPv4, used to test the local protocol stack.

Summary of all prefixes:

Unicast Prefixes

  1. Global Unicast
    • Prefix: 2000::/3
    • Usage: Public IPv6 addresses used on the Internet. These addresses are globally unique.
  2. Unique Local
    • Prefix: FC00::/7
    • Usage: Private IPv6 addresses used within an organization. These addresses are not routable on the public Internet. Typically, they start with FD.
  3. Link-Local
    • Prefix: FE80::/10
    • Usage: Automatically generated addresses used for communication within a local network segment. Not routable beyond the local link.
  4. Loopback Address
    • Prefix: ::1/128
    • Usage: Used by a device to send a packet to itself for testing. Similar to 127.0.0.1 in IPv4.
  5. Unspecified Address
    • Prefix: ::/128
    • Usage: Represents a lack of an address (used during initial setup).

Multicast Prefixes

  1. Multicast
    • Prefix: FF00::/8
    • Usage: Used to send packets to multiple destinations at once. The scope (local, site, global) is defined by the subsequent bits in the address.
    • Common Scopes:
      • FF01::/16: Interface-local (Packets don't leave the device).
      • FF02::/16: Link-local (Packets stay within the local subnet).
      • FF05::/16: Site-local (Packets are routed within a site but not beyond).
      • FF08::/16: Organization-local (Packets can be routed across an organization's network).
      • FF0E::/16: Global (Packets can be routed globally, including across the public Internet).