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Text File | 1993-12-13 | 20.1 KB | 456 lines

IP Addresses for the UK: A discussion document ============================================== Version 2, 26 June 1993 ADS Benham, G8FSL. The current IP addressing scheme (based on RSGB regions) has (at least) two problems. Firstly, the number of stations active on TCP/IP has meant that the address space of some of the regions is starting to become full: clearly if the interest in TCP/IP increases significantly there will be problems in allocating addresses (there being only 255 possible addresses per region (reserving ".255" as a broadcast address). Secondly, the allocation of addresses within each region has been in numerical order. This means that two adjacent IP addresses can be many miles (or tens of miles) apart. This makes sensible routing tables very difficult to produce (since, within a region, almost every address will be an exception to almost any routing rule). The purpose of this proposal is to attempt to solve these problems, and to create an IP addressing scheme for the U.K. which will provide a useful service for a reasonable number of years. The National proposal is closely connected (and was in fact driven by) the "hub" principle that has been operational in the Home Counties for some 9 months or so. The hub principle is intended to be the first phase of a plan to eventually create a TCP/IP packet network within the U.K. It is probable (and hoped that) that the bulk of amateur packet activity will slowly move away from "vanilla" AX25 operation towards a more layered set of protocols providing better and more sophisticated services. Whilst the protocol set may not be TCP/IP in the long term, the chosen set will almost certainly evolve from TCP/IP protocols. Thus the TCP/IP network will quite possibly provide the bulk of the U.K. network capability in the future. The "hub" (or "node", although the latter term is not preferred as it can be confused with the NET/ROM terminology) is the network access point for a TCP/IP end-user. Each hub will cover a small area- encompassing up to perhaps 10 users, operating (with low power) on a single local frequency. Each hub within a larger area (county?) will (eventually, as the network takes shape) be connected to an area hub. The links to the area hub will be high(er) speed links, and on a frequency other than that/those used for local access in the area (there are pros and cons for using a cellular approach to frequency reuse at the user access level). The area hubs will eventually be connected by high speed links to regional super-hubs, which in turn will be linked on dedicated frequencies by a U.K. backbone at the highest data rates. The objective of this network is to enhance and simplify the routing of TCP/IP traffic. Each user would have a routing table with entries for those local stations which can be reached directly. Each user's default route would be to the local hub. Each hub would have a routing table similarly with entries for local stations/hubs, and a default route to the area hub (with possible entries to send traffic for neighbouring regions to a another hub in the right geographical direction). Similarly at each higher level the default entry would be to send traffic "up the network", with fixed entries for local routes. The network would also provide centralised resources. Each local hub could provide a POP server for mail, thereby obviating the need for 24 hour a day operation by users. The local hub could also provide a domain server (updated regularly over the network), so each user need not hold a large "domain.txt" file. In order for the routing scheme outlined above to operate, a more structured approach to the allocation of IP addresses is required. This is needed so that the "sub-net mask" concept can be utilised: this is where a specified number of the leading bits in the IP address are tested for a match, and if matched then a specified route is used. For example, the command: route add 44.131.7.0/24 vhf 44.131.19.127 routes all traffic for IP addresses which have the leading ("leftmost") 24 bits matching 44.131.7.0 (i.e. the addresses 44.131.7.<any>) via station 44.131.19.127 on our port "vhf". Note 1: "route default" is functionally the same as "route add 0.0.0.0/0 ...", i.e. match any address. Note 2: "route add <address> ...." with no "/<num>" qualifier is functionally the same as "route add <address>/32 ....", i.e. all 32 bits must be matched. Note 3: where a given address matches several patterns, the pattern with the greatest degree of matching (most bits matched) is used. Thus: "route add 44.131.7.0/24 vhf 44.131.19.127" "route add 44.131.7.5 vhf 44.131.19.129" will treat "...7.5" as a special routing case. This feature is the key to the routing of traffic, in that the "users" of a given level hub have addresses which "lead on" from that of the hub. Consider the following example: End users Local Hubs Area Hubs Regional Hub 44.131.32.81-\ 44.131.32.82--+--44.131.32.80--\ 44.131.32.83-/ | | 44.131.32.97-\ | 44.131.32.98--+--44.131.32.96--+--44.131.32.64----\ 44.131.32.99-/ | | | | 44.131.32.113-\ | | 44.131.32.114--+-44.131.32.112-/ | 44.131.32.115-/ | +--44.131.32.0 44.131.32.145-\ | 44.131.32.146--+-44.131.32.144-\ | 44.131.32.147-/ | | | | 44.131.32.161-\ | | 44.131.32.162--+-44.131.32.160-+--44.131.32.128---/ 44.131.32.163-/ | | 44.131.32.177-\ | 44.131.32.178--+-44.131.32.176-/ 44.131.32.179-/ From anywhere outside this subnet, each user can be reached by a "route add 44.131.32.0/24 <port> <gateway>" command. The regional hub can split the traffic with 2 statements, namely: "route add 44.131.32.64/26 <port> 44.131.32.64" "route add 44.131.32.128/26 <port> 44.131.32.128" The area hub 44.131.32.128 has a routing table which reads (in its entirety!): "route add 44.131.32.144/28 <port> 44.131.32.144" "route add 44.131.32.160/28 <port> 44.131.32.160" "route add 44.131.32.176/28 <port> 44.131.32.176" "route default <port> 44.131.32.0" Note 1: The above example has a regular structure, although this is not essential. Note 2: It would be possible for a single site to encompass more than one level of hub. Note 3: The apparently missing addresses in the above example can be used by stations/hubs outside the regular structure. E.g. 44.131.32.1 could be the regional hub sysop, and 44.131.32.65 the sysop of 44.131.32.64. 44.131.32.32 could be a local hub directly connected to 44.131.32.0, as could 44.131.32.16 (I recommend that the above example is worked through, converting the addresses into binary. To assist, taking just the third octet: Regional hub Area hub Local hub User 00000000 01000000 01010000 01010001 01010010 01100000 01100001 01100010 10000000 10010000 10010001 10010010 10100000 10100001 10100010 ) Note: It is important to realise that the scheme is flexible, in that it can cater for situations where there are many users on few hubs, or few users on many hubs (or, to a certain extent, a combination of situations within a region or area). Clearly in order to implement a scheme such as this, the whole of the U.K. IP address allocation would have to be reworked. This is not a task to be taken lightly, but the long term benefits would seem to far outweigh the short term problems. Practical addressing schemes divide the country into regions. It must be borne in mind that any radio-based network suffers from the fact that radio waves are no respecters of county boundaries, and that whilst a station may be physically located in a given county, in RF terms the station should be considered to be in a neighbouring county (or country). Nevertheless, dividing the country into regions on a county basis is still probably the most practical method. However, with the hub scheme proposed it is no longer the location of the individual station which determines the region, but rather the location of the local hub to be used. Together with the sub-net masking of addresses, the best scheme for IP address allocation would seem to be to devolve the allocation down to the hub sysops. In order to maximise the address space for IP addresses in the U.K., it is proposed to divide the country into 32 regions. The region number can be held in 5 bits, and the 5 bits used will be the leading 5 bits in the third octet. This leaves 11 bits for addressing within the region (the 3 trailing bits of the third octet, plus the whole of the fourth octet). This would represent an 8-fold increase in address space over the current scheme if the individual regions were the same size: it is hoped that the division into regions will give an additional benefit. The base addresses of the regions will be: 44.131.0 44.131.8 44.131.16 44.131.24 44.131.32 44.131.40 44.131.48 44.131.56 44.131.64 44.131.72 44.131.80 44.131.88 44.131.96 44.131.104 44.131.112 44.131.120 44.131.128 44.131.136 44.131.144 44.131.152 44.131.160 44.131.168 44.131.176 44.131.184 44.131.192 44.131.200 44.131.208 44.131.216 44.131.224 44.131.232 44.131.240 44.131.248 The proposal for the division of the country into regions is based on the premise that the number of amateurs running TCP/IP in a county is a constant proportion of the total population of that county. Thus if the IP address space is allocated on a county-based system, then each region should have (roughly) the same number of users. The U.K. population, according to the 1992 Whittaker's Almanac, is broken down as follows: England 46.2M Scotland 4.96M Wales 2.80M N.I. 1.57M Total: 55.7M Based on the above population figures, each of the 32 regions should have approximately 1.74M people living in it, and the number of regions should be allocated thus: England: 26 Scotland: 3 Wales: 2 N.I.: 1 (The Channel Islands and the Isle of Man will be included in the nearest mainland region). Considering the individual countries: Northern Ireland: 1 region Wales: 2 regions With a population of 2.80M, each region should encompass a population of approx. 1.40M The breakdown of the Welsh population (from Whittaker's Almanac) is: Clwyd 402k Dyfed 342k Gwent 432k Gwynedd 239k Mid Glam 527k Powys 117k South Glam 383k West Glam 358k The proposed regions are therefore: Gwent; West, Mid, and South Glamorgan 1.70M Clwyd; Dyfed; Gwynedd; Powys 1.10M Scotland: 3 regions With a population of 4.96M, each region should encompass a population of approx. 1.65M The breakdown of the Scottish population (from Whittaker's Almanac) is: Borders 103k Central 268k Dumfries and Galloway 147k Fife 339k Grampian 493k Highland 209k Lothian 724k Orkney 19k Shetland 22k Strathclyde 2.22M Tayside 385k Western Isles 29k The proposed regions are therefore: Strathclyde 2.22M Dumfries and Galloway; Borders; Lothian; Fife 1.31M Central; Tayside; Highland; Grampian; Western Isles; Orkney; Shetland 1.43M England: 26 regions With a population of 46.2M, each region should encompass a population of approx. 1.78M. The breakdown of the English population (from Whittaker's Almanac) is: Avon 920k Bedfordshire 514k Berkshire 717k Buckinghamshire 620k Cambridgeshire 641k Cheshire 937k Cleveland 541k Cornwall 469k Cumbria 487k Derbyshire 915k Devon 998k Dorset 645k Durham 590k East Sussex 671k Essex 1.50M Gloucestershire 521k Greater London 6.37M Greater Manchester 2.45M Hampshire 1.51M Hereford & Worcester 668k Hertfordshire 952k Humberside 835k Isle of Wight 127k Kent 1.49M Lancashire 1.37M Leicester 860k Lincolnshire 574k Merseyside 1.38M Norfolk 736k Northamptonshire 573k Northumberland 301k North Yorkshire 699k Nottinghamshire 981k Oxfordshire 554k Shropshire 402k Somerset 459k South Yorkshire 1.25M Staffordshire 1.02M Suffolk 630k Surrey 998k Tyne & Wear 1.09M Warwickshire 477k West Midlands 2.50M West Sussex 693k West Yorkshire 1.98M Wiltshire 553k The proposed regions are therefore: 1. Cornwall,Devon,Somerset (1.93M) 2. Dorset, Wilts, Avon (2.12M) 3. Hampshire,Isle of Wight (1.64M) 4. Surrey, West Sussex (1.69M) 5. Kent, East Sussex (2.16M) 6. Greater London 1 (2.12M) 7. Greater London 2 (2.12M) 8. Greater London 3 (2.12M) 9. Essex (1.50M) 10. Herts, Beds, Bucks (2.09M) 11. Berks, Oxon (1.27M) 12. Suffolk, Norfolk, Cambs (2.01M) 13. Gloucester, Hereford & Worcester, Shropshire (1.59M) 14. Northampton, Warks, Leics (1.91M) 15. West Midlands 1 (1.25M) 16. West Midlands 2 (1.25M) 17. Lincs, Notts (1.56M) 18. Humberside, S.Yorks (2.09M) 19. Derby,Staffs (1.94M) 20. W.Yorks (1.98M) 21. N.Yorks, Cleveland (1.73M) 22. Cumbria, Northumberland, Durham, Tyne & Wear (1.98M) 23. Lancashire (1.37M) 24. Merseyside, Cheshire (2.32M) 25. Greater Manchester 1 (1.23M) 26. Greater Manchester 2 (1.23M) In the cases of Greater London, West Midlands, and Greater Manchester there are several regions covering one county. Each region is to cover a specific area of the county: London is shown below as an example (I would prefer the other two cases to be dealt with by someone with local knowledge. With 3 regions covering a population of 6.37M, each Greater London region should encompass a population of approx. 2.12M The breakdown of the population of Greater London into boroughs (from Whittaker's Almanac) is: Barking and Dagenham 140k Barnet 283k Bexley 211k Brent 226k Bromley 282k Camden 171k (City) ??? Croydon 300k Ealing 264k Enfield 249k Greenwich 201k Hackney 164k Hammersmith and Fulham 137k Haringey 187k Harrow 194k Havering 224k Hillingdon 226k Hounslow 193k Islington 155k Kensington and Chelsea 128k Kingston upon Thames 131k Lambeth 220k Lewisham 215k Merton 162k Newham 200k Redbridge 221k Richmond upon Thames 155k Southwark 197k Sutton 164k Tower Hamlets 154k Waltham Forest 203k Wandsworth 238k Westminster 182k The proposed regions are therefore: 1. Northern Boroughs: Hillingdon; Harrow; Ealing; Brent; Barnet; Enfield; Haringey; Waltham Forest; Redbridge; Barking; Havering 2.38M 2. Central Boroughs: Hammersmith; Kensington and Chelsea; Westminster; Camden; Islington; City; Hackney; Newham; Tower Hamlets; Greenwich; Lewisham; Southwark; Lambeth 2.13M 3. Southern Boroughs: Hounslow; Richmond upon Thames; Kingston upon Thames; Wandsworth; Merton; Sutton; Croydon; Bromley; Bexley 1.83M Region Numbering The proposed scheme for numbering the regions is also designed for ease of routing. Essentially the plan is to perform a binary tree structure, splitting alternate levels in the tree by North/South and East/West. The IP address regions can therefore be routed according to the leading bit(s) of the third octet. For example, if the MSB of the third octet is '0' for north and '1' for south, then a station in Scotland could route traffic for any address with a third octet value greater than 127 to the backbone. Taking '1' to represent south and east, and '0' to represent north and west, the proposed split (showing the leading 5 bits of the third octet in binary) is: (the geography of the U.K. and the proposed regions don't fall as neatly as wanted into this plan! In fact, certain of the decisions that are required to make the splitting scheme work seem very wrong!) 00000 (44.131.0-7) Strathclyde 00001 (44.131.8-15) Central, Tayside, Grampian, "Highlands and Islands" 00010 (44.131.16-23) Northern Ireland 00011 (44.131.24-31) Dumfries and Galloway, Borders, Lothian, Fife 00100 (44.131.32-39) Cumbria, North Yorkshire, Cleveland 00101 (44.131.40-47) Northumberland, Durham, Tyne and Wear 00110 (44.131.48-55) Humberside, South Yorkshire 00111 (44.131.56-63) Lincolnshire, Nottinghamshire 01000 (44.131.64-71) Merseyside, Cheshire 01001 (44.131.72-79) Derbyshire, Staffordshire 01010 (44.131.80-87) Dyfed, Powys, Gwynedd, Clwyd 01011 (44.131.88-95) Shropshire, Hereford and Worcester, Gloucestershire 01100 (44.131.96-103) Lancashire 01101 (44.131.104-111) West Yorkshire 01110 (44.131.112-119) Greater Manchester 1 01111 (44.131.120-127) Greater Manchester 2 10000 (44.131.128-135) West Midlands 1 10001 (44.131.136-143) West Midlands 2 10010 (44.131.144-151) Leicestershire, Warwickshire, Northamptonshire 10011 (44.131.152-159) Oxfordshire, Berkshire 10100 (44.131.160-167) Hertfordshire, Bedfordshire, Buckinghamshire 10101 (44.131.168-175) Cambridge, Norfolk, Suffolk 10110 (44.131.176-183) North London 10111 (44.131.184-191) Essex 11000 (44.131.192-199) Gwent, the Glamorgans 11001 (44.131.200-207) Wiltshire, Avon, Dorset 11010 (44.131.208-215) Cornwall, Devon, Somerset 11011 (44.131.216-223) Hampshire, Isle of Wight 11100 (44.131.224-231) Central London 11101 (44.131.232-239) South London 11110 (44.131.240-247) Surrey, West Sussex 11111 (44.131.248-255) Kent, East Sussex NOTE: The Channel Islands and the Isle of Man have not been included within any of the above regions. They have not been ignored in this study, but the decision of which region most sensibly fits each case has been left to those with local routing knowledge. Change History The original proposal had Kent and East Sussex as 44.131.0-7, and Strathcylde as 44.131.248-255. Kent and East Sussex were the first region to express an interest in implementing the new scheme, and as their "new" addresses would have clashed with addresses already in use (under the old "RSGB Regions" scheme) the whole numbering scheme was inverted.