- Router Discovery: used since there is no default gateway configuration:
- Every host must discover a router by sending out "Router Solicitation" messages.
- Routers will respond with a "Solicited Router Advertisement".
- Routers will also send out "Router Advertisements" at regular intervals.
- Router advertisements contain:
- The link-local address of the router;
- Info about the link (e.g. default hop limit);
- Router lifetime;
- What addresses exist on this link (e.g. global or ULA).
- SLAAC: StateLess Auto Address Configuration:
- Generate interface ID and create link-local address (i.e. EUI-64);
- Discover prefix on link through Router Advertisement messages;
- Verify address uniqueness (DAD: Duplicate Address Detection).
- DHCPv6: is not mandatory:
- Stateful DHCPv6 keeps state of client address leases;
- Provides additional information (e.g. DNS server, domain, etc.);
- Similar to IPv4 DHCP (some message types have changed);
- Stateful DHCPv6 is not commonly available in IPv6 stacks.
- Address Resolution: IPv6 neighbour discovery:
- Send out "Neighbour Solicitation" message.
- Receive "Neighbour Advertisement" reply.
- Transition Phases:
- Phase 1 - Early Adopters: IPv6 in IPv4 tunnelling from the home.
- Phase 2 - Distributed IPv6 over Ethernet for unicast services.
- Phase 3 - IPv6 over Ethernet for unicast and multicast services.
- NAT444: (LSN - Large Scale NAT)
Private IPv4 <-NAT44-> Private IPv4 <-NAT44-> IPv4 Internet
Home N/W Access N/W Stateful
- No change required to CPE.
- Have to be careful of:
- Address overlaps between customer's RFC1918 addresses and the provider-assigned RFC1918 addresses.
- Routing between end subscribers -- can use:
- Hairpinning.
- SP shared addresses.
IPv6 <--> IPv6 <-NAT64-> IPv4 Internet
Private IPv4 <-NAT46-> IPv6 <-NAT64-> IPv4 Internet
Home N/W Stateful Access N/W Stateful
- Is closer to a pure IPv6 network than NAT444.
- Eases the burden of having to assign and manage both IPv4 and IPv6 addresses on links.
- Because of translation between IPv4 and IPv6 address families:
- Is more complex than NAT444.
- Doesn't perform or scale as well as NAT444.
- DS Lite: (Dual Stack Lite)
Private IPv4 <--+--> <-NAT44-> IPv4 Internet
- Uses IPv6-only links between the customer and the provider.
- Tunnels IPv4 traffic over IPv6.
- The LSN performing the NAT44 has to also track the source address of the encapsulating IPv6 packet.
- Disadvantage is that CPE needs to be upgraded (either software or hardware), but may not be a big problem:
- It is new customers who are creating demand for new IP addresses.
- Existing customers can be upgraded as part of normal hardware refresh or churn cycles.
- DS Lite can also run in the protocol stack on an individual end system -- useful for:
- Single PC, laptop, gaming systems connected to the Internet.
- Mobile broadband.
Feature | NAT444 | NAT64 + DNS64 | NAT464 | DS Lite | Customer Premise | No CPE change | Host must support IPv6 | CPE change | CPE change | Disadvantage | Potential overlapping address space between CPE and LSN | Only supports IPv6 hosts (WinXP does not support DNS64) | IPv4 translated into IPv6 | IPv4 is tunneled over IPv6 | Traffic Bypass | Application servers can sit between subscriber and LSN | All IPv4 traffic must be subject to NAPT | All IPv4 traffic must be subject to NAPT | All IPv4 traffic must be subject to NAPT | Current BNG/BRAS | Minimal impact | Tunnel obfuscates all IPv4 traffic | Tunnel obfuscates all IPv4 traffic | Tunnel obfuscates all IPv4 traffic |
- Dual Stack: The only real problem with this is how can you dual stack if you've run out of IPv4 addresses?
- Therefore: must start to dual stack before running out of IPv4 addresses.
- Migration Options:
- Dual stack: network runs both stacks, effectively "ships in the night".
- 6over4: IPv6 tunneled over an IPv4 backbone.
- 6PE: IPv6 tunneled over an IPv4/MPLS backbone.
- 6VPE: same as 6PE, but additionally supports multiple VRFs on the PE routers.
- DS-Lite.
- 6RD.
- NAT64/DNS64.
Various IPv6-Related RFCs- RFC5569: IPv6 Rapid Deployment on IPv4 Infrastructures (6rd)
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