Transition mechanisms IPv6

1 transition mechanisms

1.1 dual ip stack implementation
1.2 tunneling

1.2.1 automatic tunneling
1.2.2 configured , automated tunneling (6in4)


1.3 proxying , translation ipv6-only hosts

transition mechanisms

ipv6 not foreseen supplant ipv4 instantaneously. both protocols continue operate simultaneously time. therefore, ipv6 transition mechanisms needed enable ipv6 hosts reach ipv4 services , allow isolated ipv6 hosts , networks reach each other on ipv4 infrastructure.

many of these transition mechanisms use tunneling encapsulate ipv6 traffic within ipv4 networks. imperfect solution, reduces maximum transmission unit (mtu) of link , therefore complicates path mtu discovery, , may increase latency. tunneling protocols temporary solution networks not support native dual-stack, both ipv6 , ipv4 run independently.

dual ip stack implementation

dual-stack ip implementations provide complete ipv4 , ipv6 protocol stacks in same network node on top of common physical layer implementation, such ethernet. permits dual-stack hosts participate in ipv6 , ipv4 networks simultaneously. method defined in rfc 4213.

dual-stack configuration desirable ipv6 implementation during transition ipv4 ipv6, avoids complexities of tunneling , security considerations, increased latency, management overhead, , reduced path mtu. however, not possible when outdated network equipment may not support ipv6.

dual-stack configurations, however, might introduce additional security issues hosts subject attacks both ipv4 , ipv6 networks. has been argued dual-stack architecture overburden global networking infrastructure requiring routers support ipv4 , ipv6 routing simultaneously.

dual-stack implementation still requires ipv4 address on every node, limited ipv4 address exhaustion, 1 of main motivations ipv6. address this, dual-stack lite or ds-lite introduced, uses network address translation , tunneling encapsulate ipv4 packets in ipv6 transport, deliver them final destination.

tunneling

many current internet users not have ipv6 dual-stack support, , cannot reach ipv6 sites directly. instead, must use ipv4 infrastructure carry ipv6 packets. done using technique known tunneling, encapsulates ipv6 packets within ipv4, in effect using ipv4 link layer ipv6.

ip protocol 41 indicates ipv4 packets encapsulate ipv6 datagrams. routers or network address translation devices may block protocol 41. pass through these devices, udp packets may used encapsulate ipv6 datagrams. other encapsulation schemes, such ayiya or generic routing encapsulation, popular.

conversely, on ipv6-only internet links, when access ipv4 network facilities needed, tunneling of ipv4 on ipv6 protocol occurs, using ipv6 link layer ipv4.

automatic tunneling

automatic tunneling refers technique routing infrastructure automatically determines tunnel endpoints. automatic tunneling techniques below.

6to4 recommended rfc 3056. uses protocol 41 encapsulation. tunnel endpoints determined using well-known ipv4 anycast address on remote side, , embedding ipv4 address information within ipv6 addresses on local side. 6to4 common tunnel protocol deployed.

teredo automatic tunneling technique uses udp encapsulation , can allegedly cross multiple nat nodes. ipv6, including 6to4 , teredo tunneling, enabled default in windows vista , windows 7. unix systems implement 6to4, teredo can provided third-party software such miredo.

isatap (intra-site automatic tunnel addressing protocol) uses ipv4 network virtual ipv6 local link, mappings each ipv4 address link-local ipv6 address. unlike 6to4 , teredo, inter-site tunneling mechanisms, isatap intra-site mechanism, meaning designed provide ipv6 connectivity between nodes within single organization.

configured , automated tunneling (6in4)

6in4 tunneling requires tunnel endpoints explicitly configured, either administrator manually or operating system s configuration mechanisms, or automatic service known tunnel broker; referred automated tunneling. configured tunneling more deterministic , easier debug automatic tunneling, , therefore recommended large, well-administered networks. automated tunneling provides compromise between ease of use of automatic tunneling , deterministic behavior of configured tunneling.

raw encapsulation of ipv6 packets using ipv4 protocol number 41 recommended configured tunneling; known 6in4 tunneling. automatic tunneling, encapsulation within udp may used in order cross nat boxes , firewalls.

proxying , translation ipv6-only hosts

after regional internet registries have exhausted pools of available ipv4 addresses, hosts newly added internet might have ipv6 connectivity. these clients have backward-compatible connectivity existing ipv4-only resources, suitable ipv6 transition mechanisms must deployed.

one form of address translation use of dual-stack application-layer proxy server, example web proxy.

nat-like techniques application-agnostic translation @ lower layers in routers , gateways have been proposed. nat-pt standard dropped because of criticisms; however, more recently, continued low adoption of ipv6 has prompted new standardization effort of technology called nat64.