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Host 4over6 For IPv6 host connecting IPv4 Internet

Yong Cui, Jianping WuTsinghua Univ. (CERNET)

Contact: cuiyong@tsinghua.edu.cn

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OutlineIntroductionElements in host 4over6Stateless approachCombination with Dual-Stack LiteStateful approachNext steps

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IntroductionPure IPv6 network

With the coming IPv4 address exhaustion, pure & native IPv6 network comes to reality

IPv4 access is still required for hosts in IPv6 network SW IPv4-over-IPv6 Hub & Spoke Some hosts need to provide IPv4 service to the IPv4 Internet Operators (CERNET) need to support all apps & avoid xlate

(NAT44 or NAT64) Use case study

high-end client (host): Hope to have global IPv4 addr to support various apps even dynamically

Servers (host): Move IPv4 servers to IPv6 networks without loss of IPv4 clients

Having global IPv4 addr will be a Value-Added Service

IPv4 Internet

IPv4 Service

NO NAT44NO NAT64

IPv6 Edge Network

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General Idea of Host 4over6Leverage some global IPv4 addresses

Operators hope to leverage their existing resource of IPv4 blocks

Assign global IPv4 addr dynamically to host or CPEBidirectional 4over6 tunnel

Use bidirectional tunnel for traversing IPv4 traffic over IPv6 networks

IPv4 Internet

IPv4 Service

NO 44 NATNO 46 NAT

Leverage IPv4 global

addressbidirectional 4over6 tunnel

IPv6 Edge Network

Elements in Host 4over6Tunnel Initiator(TI)

Host or CPE in IPv6 edge networks Request global IPv4 addr when needed Establish 4over6 tunnel toward Tunnel Concentrator

Tunnel Concentrator(TC) IPv4/IPv6 dual stack router as the 4over6 tunnel endpoint Perform encap/decap

DHCPv6 server Allocate both IPv6 address and tunnel concentrator address

to tunnel initiator Dynamically allocate

host 4over6 address to tunnel initiator

IPv4 Internet

IPv6 Edge Network

TI : host

DHCPv6 Server

TCIPv4 home network TI: CPE

host

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Stateless: DHCPv6 ExtensionAllocate tunnel concentrator IPv6 address

draft-ietf-softwire-ds-lite-tunnel-option-03Host 4over6 address (IPv4-Embedded IPv6 address)

NSP + global IPv4 addr + suffixdraft-ietf-behave-address-format-09New DHCPv6 option (OPTION_HOST_4OVER6_ADDR) to

allocate this address:

Implicitly allocate IPv4 addr by DHCPv6

OPTION_HOST_4OVER6_ADDR option-len: 16 octets

IPv4-Embedded IPv6 address

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Stateless approach4over6 Host

Request 4over6 addr from DHCPv6 serverAbstract embedded IPv4 addr and config IPv4 stackTunnel initiator Encap/Decap

TC: NO stateful mappingNeed to inject a few IPv4 prefix into IPv6 RT

Only in one IPv6 edge network (NSP-based)

IPv4 network

IPv4 Internet

IPv6 Edge Network

host

DHCPv6 Server

TC

Request host 4over6 addr

NSP IPv4 SuffixConcentrator Addr

v6 Srcv6 Dest

Global v4 Srcv4 Dst

payload

Global IPv4

v6 Srcv6 Dest

Global v4 Srcv4 Dst

payloadGlobal v4 Src

v4 Dst

payload

v6 Srcv6 Dest

Global v4 Srcv4 Dst

payloadGlobal v4 Src

v4 Dst

payload

Concentrator AddrNSP IPv4 Suffix

CPE

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CPE functionDHCP46: request host 4over6 address from DHCPv6 server

when host launch global DHCPv4 request to CPETunnel Initiator: Encapsulation/decapsulation

IPv4 hostNo any change in CPE mode

Stateless approach (CPE scenario)

IPv4 Internet

IPv6 Edge Network

host

DHCPv6 Server

TC

Request global ipv4

CPE

DHCP46

Request host

4over6 addrReply host

4over6 address

CPE reply global IPv4 addr

Global v4 Srcv4 Dst

payload

v6 Srcv6 Dest

Global v4 Srcv4 Dst

payloadIPv4 network

IPv4 Internet

Combination with Dual-Stack Lite:Host scenario

DHCPv6 serverUse the same DHCPv6 option to get the concentrator IPv6

address (draft-ietf-softwire-ds-lite-tunnel-option-03)Add an option for 4over6(OPTION_HOST_4OVER6_ADDR)

Tunnel concentratorOutbound, differentiate by Src addr

Public – host 4over6; Private – DS-liteInbound Differentiate by Dst addr

In CGN address pool – DS-lite; otherwise: host 4over6IPv6 Edge Network

Host4over6SERVER

DS-liteCLIENT

TC

Inform the

TC IPv6 addr

DHCPv6 ServerLaunch a DS lite process

DHCPv6 with option HOST_4OVER6

Launch a host 4ovr6 process

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What Host 4over6 achieves?Support bidirectional communication

Leverage existing global IPv4 addressSupport both IPv4 clients and IPv4 servers

Avoid NAT44 to support all appsAvoid per flow state maintenanceCan easily combine with DS-LiteEncourage IPv4 servers move to IPv6 without

loss of IPv4 usersEnsure high-priority host to have full access to

IPv4 without NATProvide value-added service

Stateful approach of Host 4over6Tunnel concentrator maintains global IPv4 addr poolInitiator uses both DHCPv6 & DHCPv4

Request TC’s IPv6 addr from DHCPv6 server with DS-Lite tunnel option

Request IPv4 addr from DHCPv4 server (TC) with DHCPv4 over IPv6 tunnel

Concentrator maintains the state of address mappingHost global IPv4 address: Host IPv6 address

IPv4 Internet

IPv6 Edge Network

DHCPv6 Server

TC4over6

Host

DHCPv6TC IPv6 addr

DHCPv4 over IPv6 tunnel

Mapping (not per flow): Global IPv4 addr – IPv6 addr

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Next stepSet up a design team…

cuiyong@tsinghua.edu.cnjianping@cernet.edu.cn

Implementation on host/CPE/TCAsk for accepting as WG documentValuable comments

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