Adoption of a hierarchical bit-mapped addressing scheme
for IP Addresses for the UK from 9306000000

(previously issued as IP Addresses for the UK: A discussion document by G8FSL for
the London & Home Counties TCP/IP Group 930808 but now includes some radical
changes to bit-masking and additions on hub and cellular designs as field tested in
the last year.g1plt)

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 document 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 proposal is closely connected (and, in fact, driven by) the 'hub principle' that
was proposed by Paul Taylor g1plt in March 1992 and has been 'tested' in the Home
Counties over the last year.

The 'hub principle' is intended to be the first phase of a plan to eventually create a
resilient 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.Termed a 'Local Access Point' Each hub will cover a small area -
encompassing up to perhaps 10 users, operating(with low power) on a single local
access frequency and then the "hub" connects on a HUB linking frequency to a
minimum of 2 or 3 other hubs to form a CELL. This then follows typical cellular
systems in the re-use of frequencies on adjacent cells. It is VERY IMPORTANT that
the HUBs have a 100% solid RF link to each other and that the software is reliable
running the HUB,it should be stress tested before committing it for hub operations.

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 access to a POP server for mail, thereby obviating the need for 24 hour a
day operation by users. Similarly, Network News can be delivered from a suitable
NNTP server. A CONVERS server could also be accessed from the HUB. The local
HUB could also provide access to a domain server (updated regularly over the
network), so each user need not hold a large "domain.txt" file.

Some areas have combined the above server operations into a single machine
dedicated to running a HUB. Whilst this may seem a sensible solution in the
beginning, it would be wise to plan for separate machines, one running MAILBOX
type operations within the HUB area and another running ROUTING and DOMAIN
at the HUB.

The HUB is the beginning of the infrastructure required to create a integrated
network for its users, its intentionally low power as it only needs to serve up to 16
users. Due to the design of current HDLC AX25v2 protocol WITH the use of FM
capture effect this number of users will ensure a reasonable throughput if location of
the HUB's are carefully placed.It should NOT be placed on top of a hill so that it
dominates the surrounding areas, It will be better to use an amateur who is so placed
as a router on a uhf/shf frequency for linking HUB's(where he/she also can obtain
local access/frequency translation without causing un-necessary interference)

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.) 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 ...." with no "/" qualifier is functionally the
same as "route add /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 " command.

The regional hub can split the traffic with 2 statements, namely:
"route add 44.131.32.64/26 44.131.32.64"
"route add 44.131.32.128/26 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 44.131.32.144"
"route add 44.131.32.160/28 44.131.32.160"
"route add 44.131.32.176/28 44.131.32.176"
"route default 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. Inner London 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 128 to the backbone.

Taking '0' to represent north and west, and '1' to represent south and east, 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!)

| = Activated AS @ 950401
*= Partial Activation AS @ 950401
+= AGREED TO Change TO hierarchical system
u5bit number
00000 000-007 Strathclyde
00001 008-015 Central, Tayside, Grampian, "Highlands and Islands"
00010 016-023 Northern Ireland
00011 024-031 Dumfries and Galloway, Borders, Lothian, Fife
+ 00100 032-039 Cumbria, North Yorkshire, Cleveland
+ 00101 040-047 Northumberland, Durham, Tyne and Wear
+ 00110 048-055 Humberside, South Yorkshire
+ 00111 056-063 Lincolnshire, Nottinghamshire
+ 01000 064-071 Merseyside, Cheshire
01001 072-079 Derbyshire, Staffordshire
+ 01010 080-087 Dyfed, Powys, Gwynedd, Clwyd
* 01011 088-095 Shropshire, Hereford and Worcester, Gloucestershire
01100 096-103 Lancashire
01101 104-111 West Yorkshire
+ 01110 112-119 Greater Manchester 2
+ 01111 120-127 Greater Manchester 1
| 10000 128-135 West Midlands 2
| 10001 136-143 West Midlands 1
| 10010 144-151 Leicestershire, Warwickshire, Northamptonshire
| 10011 152-159 Oxfordshire, Berkshire
| 10100 160-167 Hertfordshire, Bedfordshire, Buckinghamshire
+ 10101 168-175 Cambridge, Norfolk, Suffolk
| 10110 176-183 North London
| 10111 184-191 Essex
+ 11000 192-199 Gwent, the Glamorgans
+ 11001 200-207 Wiltshire, Avon, Dorset
+ 11010 208-215 Cornwall, Devon, Somerset
* 11011 216-223 Hampshire, Isle of Wight
| 11100 224-231 Central London
| 11101 232-239 South London
| 11110 240-247 Surrey, West Sussex
| 11111 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.

NOTE2: The original plan was to start the scheme from the south-east corner of the
UK but to stop any likely clash of 'old numbers' being mistaken by the new scheme
the assignment was inverted as above.

Ref: 1:Paul Taylor G1PLT's Presentation on 'The Hub System and hierarchical
bit-mapped addressing scheme' to the London and Home Counties TCP/IP
Group 920401.
Outline of HUB operations and principles for local/regional
national/international interconnected networks
2:Andrew Benham G8FSL's IP addressing scheme for UK:
A Discussion Document. tabled at the London & Home Counties meeting
920808 and distributed to tcpip@gbr.
which outlined the ideas proposed in ref 1 (in a much better readable
document than I did g1plt) and included the division of 44.131.x.x series into
counties etc.

Acknowledgments:
In particular I would like to thank various members and users of
the London and Home Counties TCP/IP Group for the trials and tribulations of
being the pilot study group enabling the changes that were used in this document.
Paul Taylor...g1plt 930501
[amended detail of adoptions 950401, on 950331 g1plt]