IPv6 Address and Migration Challenges

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IPv6 Address and Migration Challenges Outline

IPv6 Address and Migration Chal enges Peter.J.Wil is@bt.com

Contents – IPv6 Addresses  sTLAs are too smal . NLAs are too smal . IPv6 Address Hierarchies, which one? Commercial restraints caused by the address al ocation rules.  Alternative schemes. My crystal bal . © British Telecommunications plc 2001 2

Contents  IPv6 Deployment Chal enges – Cost model ing of migration.- Suggested strategy for migration  Where are the NGN applications? Home Networks – Home gateways- Addressing & naming in context- Its about communications not architectures. © British Telecommunications plc 2001 3

Why is address structure important?  Address structure is more than the total number of bits.  It is the address format & structure that defines the fundamental nature of a network. (Think of the close relationship between IPv4 address structures & the Internet.)  The structure can define the way you build networks. If you get the structure wrong it costs you money to build a network to make that address structure work. (Think of the cost of memory for al those IPv4 routes.) © British Telecommunications plc 2001 4

IPv6 – Addressing Issues Internet Assigned Numbers Authority Registries eg. 2001::/23 Internet Service Providers (ISP’s)Exchanges / Carriers eg. 2001:618::/35 Sites / SME’s / Home Users (Site) eg. 2001:618:100B::/48 Mobile Phones / Home AppsPDA’s eg. 2001:618:100B:F8:/64 © British Telecommunications plc 2001 5

sTLAs Are Too Smal  Currently IPv6 network service providers (NSP) are using sub-TLAs during the boot-strap phase of IPv6.  The sTLA is a /35 The first 13 bits after the /35 is the NLA (Next- Level Aggregation) Identifier.  This NLA space has to be used to address the customers & describe the NSP topology. If the customer is an ISP then they too have to use the NLA space. (Ripe-196) © British Telecommunications plc 2001 6

NLA Field Explained  Sub-TLA holders have 13bits of Next Level Aggregation (NLA ID) Example 1 /35 /40 /48 NLA1 NLA2 NLA1, 5 bit = 32 ISPs & NLA2, 8 bits = 256 End sites Example 2 /35 /43 /48 NLA1 NLA2 NLA1, 8 bits = 256 ISPs & NLA2, 5 bits = 32 End sites © British Telecommunications plc 2001 7

Sub-TLA IDs – Use the reserved field  NLA field can grow from 13 bits to 19 bits using the reserved bits /29 /35 /48 /64 subTLA R NLA SLA Interface E 2001:618::/35 S 13 16 64 bits 13 bits = 8,192 /48’s per subTLA /29 /48 /64 subTLA NLA SLA Interface2001:618::/29 19 16 64 bits 19 bits = 524,288 /48’s per subTLA © British Telecommunications plc 2001 8

Using the NLA Hierarchical y  In NGNs with bil ions of attached devices the only way networks wil scale wil be with a deep hierarchy.  To keep the routing table to a minimum size each layer of the hierarchy must do near perfect routing aggregation.  Lets explore some network hierarchies and see how many bits are required: © British Telecommunications plc 2001 9

Network Addressing Scheme1 Hierarchical Size Number of bits Level Continent 7 3 Country 221 8 State/County 64 6 Town 128 7 Line/Site 1024 10 Total = 34 bits © British Telecommunications plc 2001 Remember current NLA size = 24 bits. +8 more reserved bits 10

Network Addressing Scheme2 Hierarchical Size Number of bits Level International backbone 10 PoPs 4 Continental backbone 20 PoPs 5 Country backbone 1000 PoPs 10 Lines to customers 1024 lines 10 Total = 29 bits Remember current NLA size = 24 bits. +8 more reserved bits © British Telecommunications plc 2001 11

Network Addressing Scheme3 and NLA Size Conclusion •Assume very efficient address al ocation without any network hierarchy (not a recommended design!)then how many lines to customers could we have with a 24 bit NLA? 2^24 = 16 Mil ion. •Using the Huitema-Durand method then 31 bits is required to address 30 Mil ion homes. (See notes)•Simply a NLA of 24 bits is not big enough for a global network operator nor big enough for a UK operator aiming to reach every home.•A 34 bit NLA should be sufficient. © British Telecommunications plc 2001 12

IPv6 Address Hierarchies, which one? • RFC 2450 “Proposed TLA and NLA Assignment Rules F TLA sub NLA SLA INTERFACE P ID TLA ID ID ID /3 /16 /29 /48 /64 • RIPE 196 “Provisional IPv6 Assignment and Al ocation Policy Document” F TLA sub R NLA SLA INTERFACE E P ID TLA S ID ID ID /3 /16 /29 /35 /48 /64 • RFC 2374 “An Aggregatable Global Unicast Address Format” F R TLA E NLA SLA INTERFACE P ID S ID ID ID /3 /16 /24 /48 /64 © British Telecommunications plc 2001 13

IPv6 Address Hierarchies,even more? • draft-ietf-ipngwg-addr-arch-v3-06.txt Now an RFC. global routingSubnet INTERFACE prefix ID ID n bits m bits 128-n-m bits See also http://www.apnic.net/meetings/12/sigs/joint_ipv6.html RIPE 40 1st October Prague http://www.ripe.net /ripe/meetings/current/ripe-40/index.html © British Telecommunications plc 2001 14

Commercial restraints caused by the address al ocation rules.  The TLA/NLA/SLA structuring and address assignment rules drives a commercial model of customers dependent on Tier 2 ISPs dependent on Tier 1 ISPs.  This is not the way it works with 3G! Slow start rules provide unfair competitive advantage to established & large networks.  Address utilisation targets if set too high cause a flattening of network hierarchy which leads to higher engineering costs. © British Telecommunications plc 2001 15

Alternatives  draft-hain-ipv6-pi-addr-00.txt “An IPv6 Provider-Independent Global Unicast Address Format”. The users IPv6 address is derived from their latitude and longitude.  Increase the number of bits in the global routing prefix by reducing the number in the interface id. Then al ow any ISP unqualified address space.  The ideal situation is that every ISP has enough address space to address everyone. © British Telecommunications plc 2001 16

My Crystal Bal  In the short term looking to see some improvement in the IPv6 address structure and al ocation rules in the current RIRs considerations.  In the long term I expect IPv6.1 which wil make much better use of the 128 bit address space. © British Telecommunications plc 2001 17

IPv6 Deployment Strategy:Cost Modelling of IPv6 Migration  Understanding the business case for deploying IPv6 is the first key step.  Understanding the costs of IPv6 is key and it is the costs that wil form a significant obstacle.  Your IPv6 deployment strategy should seek to minimise costs and maximise commercial advantages. © British Telecommunications plc 2001 18

IPv6 Migration Costs Study  The study looked at the whole costs of migrating to IPv6 for the fol owing scenarios: – A Big or Tier1 ISP – A Big enterprise- A SME- A Dial-ISP  The study examined the costs of migrating now and migrating in 5 years time.  Extra maintenance costs included. © British Telecommunications plc 2001 19

IPv6 Migration Costs Assumptions  Attempted to include al costs, including new software, memory, hardware, OSS and desktop upgrades.  Extra maintenance costs assume the extra costs of running IPv6 on an existing IPv4 network. That is assuming a dual-stack scenario.  Once IPv4 is phased out then extra- maintenance costs no longer apply.  Application migration costs not included but al owed for with BITS s/w for legacy IPv4 applications that could not be migrated. © British Telecommunications plc 2001 20

Big ISP Migration CostsBig ISP equivalent to a Tier 1 ISP £4K Cost/ customer Max cost £2K £1K Min cost Now +5 Years © British Telecommunications plc 2001 21

Big ISP Extra Maintenance CostsBig ISP equivalent to a Tier 1 ISP £200 Cost/ customer £100 £50 Max costMin cost Now +5 Years © British Telecommunications plc 2001 22

Big Enterprise Migration Costs 100,000 Desktops £1K Cost/ Employee £500 Max cost £250 Min cost Now +5 Years © British Telecommunications plc 2001 23

Big Enterprise Extra Maintenance Costs 100,000 Desktops £100 Cost/ Employee £50 £25 Max costMin cost Now +5 Years © British Telecommunications plc 2001 24

Dial-ISP Migration Costs1 Mil ion lines £30 £20 Cost/ Line Max cost £10 Min cost Now +5 Years © British Telecommunications plc 2001 27

Dial-ISP Extra Maintenance Costs 1 Mil ion lines £7.5 £5 Cost/ Line £2.5 Now +5 Years © British Telecommunications plc 2001 28

Recommendations  Do not upgrade to IPv6 now but plan to do it in about 5 years time.  Ensure as kit & software is churned or upgraded for operational reasons that it is upgraded to be IPv6 capable.  Start work on your IPv6 upgrade strategy now. Waiting for the kil er IPv6 application or until your competition has upgraded to IPv6 could be more expensive than a planned gradual upgrade in IPv6 capability.  Once IPv6 is deployed shortening the life time of IPv4 wil reduce maintenance costs. © British Telecommunications plc 2001 29

Where are the NGN applications?  NGN is not the same as IPv6. What is stopping NGN applications being deployed in IPv4?  If you have an application but can’t deploy it because of a lack of IPv4 addresses or because IPv6 not widely deployed we need to know! © British Telecommunications plc 2001 30

Home Networks and IPv6  When thinking about naming & addressing we need to consider the context of the communications.  The residential/home gateway may be a better place to manage communications in & out of the house.  The Internet’s end-to-end architecture may no longer be appropriate. Architectures develop as technology changes.  “Meta networks” with “intel igent” translation of messages at the edge of network domains may now be more appropriate. SIP & NAT are examples. This gives security & control (no more dDOS attacks).  Given a “SIP” that works then global IP addresses are no longer needed – communications routed on names. (XML routing is another alternative tech.) © British Telecommunications plc 2001 31

Conclusion  As an industry we need to make sure we don’t make the same “Class A,B,C” mistake we made with IPv4. That is not thinking about the future.  If IPv6 happens the costs of migrating to it can be mitigated by an IPv6 upgrade strategy applied now.  Don’t become religious about architectural principles that were created in a different technological era. © British Telecommunications plc 2001 32

Thank you. Peter.J.Wil is@bt.com