1. 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. 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. 3 IPv6 Prefix from an IPv4 Address  The following construction is what allows 6rd to be SP-managed and Stateless Subnet-ID 64 2001:db8 0 /n ISP 6rd IPv6 Prefix Interface ID 198.51.100.1 /m Subscriber IPv4 address Subscriber Delegated IPv6 Prefix

4. 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. 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. 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. 7 Q: What should /n and /m be? Subnet-ID 64 2001:db8 0 /n ISP 6rd Prefix Interface ID 198.51.100.1 /m IPv4 (0-32 bits)

8. 8 Starting simple: /n = 28, /m = 60 Subnet-ID 64 2001:db8 0 /28 ISP 6rd IPv6 Prefix Interface ID 198.51.100.1 /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. 9 But what if you cannot get a /27? /n = 32, /m = 64 2001:db8 0 /32 ISP 6rd IPv6 Prefix Interface ID 198.51.100.1 /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 802.15.4 for Sensors, Zigbee, etc. Ultimately leads to IPv6 NAT

10. 10 Using less than 32 bits of IPv4 Subnet-ID 64 2001:db8 0 /32 Interface ID.51.100.1 /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 10 6464 2001:db80:0 0 /36 Interface ID.51.100.1 /60 24 bits

11. 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. 12 How do I get my /27? "2^(48-(P+1))""2^(48-(P+1)) + Growth" Growth ->20%10%5%0% Prefix Size Years ->3330 2233,554,43219,418,07425,209,94128,985,58033,554,432 2316,777,2169,709,03712,604,97114,492,79016,777,216 248,388,6084,854,5196,302,4857,246,3958,388,608 254,194,3042,427,2593,151,2433,623,1974,194,304 262,097,1521,213,6301,575,6211,811,5992,097,152 271,048,576606,815787,811905,7991,048,576 28524,288303,407393,905452,900524,288 29262,144151,704196,953226,450262,144 30131,07275,85298,476113,225131,072 3165,53637,92649,23856,61265,536  /27 yields /60 for the home  /29 yields /62 for the home

13. 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?