Route Scaling and Multihoming Martin Me Court Masters of Science in Computing 2 0 0 6 Institute of Technology, Sligo Route Scaling and Multihoming M.Sc in Computing Contents Route Scaling and Multihoming..................... i C ontents.................................................................................................................................................... i List of Figures........................................................................................................................................iv List of Tables.........................................................................................................................................vi A bstract.....................................................................................................................................................1 Acknowledgment................................................................................................................................... 2 Chapter 1 - Introduction..................................................................................................................... 3 Chapter 2- IPv6 Format.................................................................................................................... 10 Field Descriptions..............................................................................................................................11 Version........................................................................................................................................... 11 Traffic Class.................................................................................................................................. 11 Flow Label......................................................................................................................................11 Payload Length..............................................................................................................................12 Next Header................................................................................................................................... 13 Hop Lim it.......................................................................................................................................13 Source Address...................................... ............................................13 Destination Address..................................................... .-............ .....13 Extension Headers...................................................................................................................... 14 Hop-by-Hop Options Header...................................................... 16 Routing Header............................................................... 16 Fragment H eader....................................................................... 17 Destination Options Header........................................................................................................18 IPv6 Addressing...................................................................................................................................20 IPv6 Address Types..................................................................................................................... 20 Address Notation..........................................................................................................................21 Text Representation of Address Prefix.....................................................................................22 Format Prefixes............................................................................................................................ 22 IPv6 Address Allocation....................................................... 25 Recommendations on IPv6 Address Allocations to Sites......................................................25 Address Assignment examples.................................................................. 26 Martin Me Court 2005 Route Scaling and Multihoming M.Sc in Computing C hapter 3 - B order Gateway P rotocol..........................................................................................27 Local Preference...........................................................................................................................29 Multi-Exit Discriminator (MED)............................................................................................... 29 Origin Attribute................................................................................. 30 AS Path Attribute.......................................................................................................................... 30 Next Hop Attribute....................................................................................................................... 30 Community Attribute.................................................................................................................. 31 Chapter 4 - Route Scaling Techniques in IPv4............................................................................32 Route Scaling................................................................................................................................32 Classless Interdomain Routing (CIDR)....................................................................................33 Route Aggregation........................................................................................................................34 Multihoming..................................................................................................................................35 Existing Multihoming Techniques............................................................................................36 Auto Route Injection BGP-4 [RFC2260]...........................................................................36 Non Direct eBGP Peering BGP-4 [RFC2260]...................................................................37 Solution 3 Provider Independent Addressing [RFC1518]...............................................38 Solution 4 Prefix Filtering [RFC1518]................................................................................ 38 Address Space Fragmentation....................................................................................................41 Chapter 5 - Address Scaling Techniques in IPv4....................................................................... 43 Network Address Translation.............................................................................. 43 Chapter 6 - Multihoming with NAT .............................................................................................. 46 DNS with Bidirectional NAT.....................................................................................................47 Externally Originated Connection.............................................................................................47 Conclusion..................................................................................................................................... 49 Chapter 7 - Financial Incentives for Route Aggregation......................................................... 51 Chapter 8 - Multihoming in IPv6.................................................................................................... 54 Chapter 9 - Comparison of Multihoming Techniques.............................................................. 58 Auto Route Injection.................................................................................................................... 58 Non Direct Peering.......................................................................................................................60 Network Address Translation..................................................................................................... 61 Financial Incentives for Route Aggregation............................................................................62 Multihoming in IPv6.................................................................................................................... 63 Conclusion..................................................................................................................................... 65 Martin Me Court 2005 i i Route Scaling and Mullihoming M.Sc in Computing Bibliography......................................................................................................................................... 66 Marlin Me Court 2005 111 Route Scaling and Multihoming M.Sc in Computing List of Figures Figure 1 Active BGP Entries (www.potaroo.net).............................................................................. 5 Figure 2 Active BGP Entries 2004-2005 (www.potaroo.net)...........................................................5 Figure 3 Average Span of BGP Advertisements (www.potaroo.net).............................................7 Figure 4 Specific Prefix Advertisements (www.potaroo.net)...........................................................8 Figure 5 IPv6 Header format..............................................................................................................10 Figure 6 TLV Format.......................................................................................................................... 14 Figure 7 Use of Extension headers.....................................................................................................15 Figure 8 Hop-by-Hop Options header...............................................................................................16