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Host 4over6 For IPv6 host connecting IPv4 Internet
Yong Cui, Jianping WuTsinghua Univ. (CERNET)
Contact: [email protected]
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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…
[email protected]@cernet.edu.cn
Implementation on host/CPE/TCAsk for accepting as WG documentValuable comments
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