1 Issue Definition*: 6RD and IPv6 allocation policy Jan Žorž (Go6 Institute Slo) Mark Townsley (Cisco) *Or, Why we had to wake up on Friday to be here?
2 Aspects of IPv6 Transition Mechanisms Tunnel or Translate Stateless or Stateful SP-Managed or not SP-Managed 6rd is a Stateless, SP-Managed, Tunneling Protocol
3 IPv6 Prefix from an IPv4 Address The following construction is what allows 6rd to be SP-managed and Stateless Subnet-ID :db8 0 /n ISP 6rd IPv6 Prefix Interface ID /m Subscriber IPv4 address Subscriber Delegated IPv6 Prefix
4 6rd – Encapsulation and Packet Flow IPv4-only Access Network CE 6rd 6rd Border Relays Dual Stack 6rd IPv4 IPv6 in IPv4 (protocol 41) encapsulation Within a domain, IPv6 traffic follows IPv4 routing CEs reach BRs via IPv4 anycast “…externally 6rd looks, feels and smells like native IPv6 ” – RIPE Labs
5 CE 6rd 6rd Border Relays Dual Stack 6rd 6rd – CE Provisioning 6rdPrefix 6rdPrefixLen IPv4MaskLen 6rdBRIPv4Address Each 6rd CE within a 6rd Domain requires a single DHCP option* carrying 4 values These 4 values are the same for all CEs within the domain *May also be configured with TR-69 or otherwise IPv4
6 6rd – Deployments CE 6rd 6rd Border Relays Dual Stack 6rd IPv4 Defined in RFC 5969 Commercially available products from a number of vendors First deployment in 2007, multiple deployments today
7 Q: What should /n and /m be? Subnet-ID :db8 0 /n ISP 6rd Prefix Interface ID /m IPv4 (0-32 bits)
8 Starting simple: /n = 28, /m = 60 Subnet-ID :db8 0 /28 ISP 6rd IPv6 Prefix Interface ID /60 32 bits One 6rd domain 6rd provisioning is identical for all CEs Convenient conversion between subscriber IPv6 and IPv4 address Allows 16 IPv6 subnets in the home ISP needs a /27 or shorter
9 But what if you cannot get a /27? /n = 32, /m = :db8 0 /32 ISP 6rd IPv6 Prefix Interface ID /64 32 bits Still a single domain, but /64 does not allow multiple subnets for the subscriber No subnets, no routing Common features such as Guest + Home SSIDs become very difficult Support for for Sensors, Zigbee, etc. Ultimately leads to IPv6 NAT
10 Using less than 32 bits of IPv4 Subnet-ID :db8 0 /32 Interface ID /56 If the IPv4 space is an aggregate, 6rd need not carry the common bits For example, in a CGN world of 10/8, we just don’t carry around the :db80:0 0 /36 Interface ID /60 24 bits
11 Multiple 6rd Domains 8 bits 32 bits ISP 6rd IPv6 Prefix Interface ID (64 bits) 20 bits Distinct IPv4 Aggregates 8 bits 32 bits Interface ID (64 bits) 16 bits 8 bits 32 bits Interface ID (64 bits) 18 bits 8 bits 32 bits Interface ID (64 bits) 19 bits More efficient in terms of IPv6 space usage However, CEs in different domains require different configuration Operations begin to get more complicated, traffic patterns not as efficient, etc. 3 bits 4 bits 8 bits 4 bits IPv4 /12 IPv4 /16 IPv4 /14 IPv4 /11
12 How do I get my /27? "2^(48-(P+1))""2^(48-(P+1)) + Growth" Growth ->20%10%5%0% Prefix Size Years -> ,554,43219,418,07425,209,94128,985,58033,554, ,777,2169,709,03712,604,97114,492,79016,777, ,388,6084,854,5196,302,4857,246,3958,388, ,194,3042,427,2593,151,2433,623,1974,194, ,097,1521,213,6301,575,6211,811,5992,097, ,048,576606,815787,811905,7991,048, ,288303,407393,905452,900524, ,144151,704196,953226,450262, ,07275,85298,476113,225131, ,53637,92649,23856,61265,536 /27 yields /60 for the home /29 yields /62 for the home
13 Possible solutions 1.Declare this is a non-problem 2.Special 6rd policy. e.g., /27 granted based on ability and intention to deploy more rapidly with 6rd 3.Allow /29 to anyone 4.Others?