[ppml] Increase the flexibility of IP allocations to facilitate planning

Leo Bicknell bicknell at ufp.org
Tue Jul 22 11:41:04 EDT 2003


In a message written on Tue, Jul 22, 2003 at 09:42:11AM -0400, Whipple, Scott (CCI-Atlanta) wrote:
> I would also disagree that the 80% usage requirement is to stringent.

FWIW, attached is a data file.  The first column is how many addresses
your customer needs, the second is the smallest block you can give
them if we assume they get a single block, obviously by giving them
multiple blocks you could be more efficient, but I don't think
anyone believes that is a good practice.  The interesting thing
about this is at the bottom, if you average the averages (total
average usage) you get 75%.

So, if you ask your customers "how many devices you have" and record
that number, and they are randomly distributed, and you always
assign the smallest possible block, you'll never get above 75%
utilization on average.

This is a problem for some, and not for others.  For instance, if
your a dial-up, dsl, or cable modem shop you can likely insure a
close to subnet size number of people are on a subnet.  However if
you're selling T1's or business DSL, the reality is 75% is a _upper
bound_ on how well you can do, if we assume a single subnet per
customer.

Now, I'm not suggesting this is a real problem.  However depending on
how pedantic you want to be about 80%, or what level of detail you want
to see on allocations it is a very real issue.  Add in needing to
allow for growth on some customers (which may or may not happen in the
original predicted time frame) and it can be somewhat difficult to 
meet the 80% rule, even if you're doing the right things.

-- 
       Leo Bicknell - bicknell at ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
Read TMBG List - tmbg-list-request at tmbg.org, www.tmbg.org
-------------- next part --------------
IP's Needed	Block Size Assigned	Block Utilization
1		/32			100%
2		/31			100%
3		/29			62.5%
4		/29			75%
5		/29			87.5%
6		/29			100%
7		/28			56.2%
8		/28			62.5%
9		/28			68.7%
10		/28			75%
11		/28			81.2%
12		/28			87.5%
13		/28			93.7%
14		/28			100%
15		/27			53.1%
16		/27			56.2%
17		/27			59.3%
18		/27			62.5%
19		/27			65.6%
20		/27			68.7%
21		/27			71.8%
22		/27			75%
23		/27			78.1%
24		/27			81.2%
25		/27			84.3%
26		/27			87.5%
27		/27			90.6%
28		/27			93.7%
29		/27			96.8%
30		/27			100%
31		/26			51.5%
32		/26			53.1%
33		/26			54.6%
34		/26			56.2%
35		/26			57.8%
36		/26			59.3%
37		/26			60.9%
38		/26			62.5%
39		/26			64%
40		/26			65.6%
41		/26			67.1%
42		/26			68.7%
43		/26			70.3%
44		/26			71.8%
45		/26			73.4%
46		/26			75%
47		/26			76.5%
48		/26			78.1%
49		/26			79.6%
50		/26			81.2%
51		/26			82.8%
52		/26			84.3%
53		/26			85.9%
54		/26			87.5%
55		/26			89%
56		/26			90.6%
57		/26			92.1%
58		/26			93.7%
59		/26			95.3%
60		/26			96.8%
61		/26			98.4%
62		/26			100%
63		/25			50.7%
64		/25			51.5%
65		/25			52.3%
66		/25			53.1%
67		/25			53.9%
68		/25			54.6%
69		/25			55.4%
70		/25			56.2%
71		/25			57%
72		/25			57.8%
73		/25			58.5%
74		/25			59.3%
75		/25			60.1%
76		/25			60.9%
77		/25			61.7%
78		/25			62.5%
79		/25			63.2%
80		/25			64%
81		/25			64.8%
82		/25			65.6%
83		/25			66.4%
84		/25			67.1%
85		/25			67.9%
86		/25			68.7%
87		/25			69.5%
88		/25			70.3%
89		/25			71%
90		/25			71.8%
91		/25			72.6%
92		/25			73.4%
93		/25			74.2%
94		/25			75%
95		/25			75.7%
96		/25			76.5%
97		/25			77.3%
98		/25			78.1%
99		/25			78.9%
100		/25			79.6%
101		/25			80.4%
102		/25			81.2%
103		/25			82%
104		/25			82.8%
105		/25			83.5%
106		/25			84.3%
107		/25			85.1%
108		/25			85.9%
109		/25			86.7%
110		/25			87.5%
111		/25			88.2%
112		/25			89%
113		/25			89.8%
114		/25			90.6%
115		/25			91.4%
116		/25			92.1%
117		/25			92.9%
118		/25			93.7%
119		/25			94.5%
120		/25			95.3%
121		/25			96%
122		/25			96.8%
123		/25			97.6%
124		/25			98.4%
125		/25			99.2%
126		/25			100%
127		/24			50.3%
128		/24			50.7%
129		/24			51.1%
130		/24			51.5%
131		/24			51.9%
132		/24			52.3%
133		/24			52.7%
134		/24			53.1%
135		/24			53.5%
136		/24			53.9%
137		/24			54.2%
138		/24			54.6%
139		/24			55%
140		/24			55.4%
141		/24			55.8%
142		/24			56.2%
143		/24			56.6%
144		/24			57%
145		/24			57.4%
146		/24			57.8%
147		/24			58.2%
148		/24			58.5%
149		/24			58.9%
150		/24			59.3%
151		/24			59.7%
152		/24			60.1%
153		/24			60.5%
154		/24			60.9%
155		/24			61.3%
156		/24			61.7%
157		/24			62.1%
158		/24			62.5%
159		/24			62.8%
160		/24			63.2%
161		/24			63.6%
162		/24			64%
163		/24			64.4%
164		/24			64.8%
165		/24			65.2%
166		/24			65.6%
167		/24			66%
168		/24			66.4%
169		/24			66.7%
170		/24			67.1%
171		/24			67.5%
172		/24			67.9%
173		/24			68.3%
174		/24			68.7%
175		/24			69.1%
176		/24			69.5%
177		/24			69.9%
178		/24			70.3%
179		/24			70.7%
180		/24			71%
181		/24			71.4%
182		/24			71.8%
183		/24			72.2%
184		/24			72.6%
185		/24			73%
186		/24			73.4%
187		/24			73.8%
188		/24			74.2%
189		/24			74.6%
190		/24			75%
191		/24			75.3%
192		/24			75.7%
193		/24			76.1%
194		/24			76.5%
195		/24			76.9%
196		/24			77.3%
197		/24			77.7%
198		/24			78.1%
199		/24			78.5%
200		/24			78.9%
201		/24			79.2%
202		/24			79.6%
203		/24			80%
204		/24			80.4%
205		/24			80.8%
206		/24			81.2%
207		/24			81.6%
208		/24			82%
209		/24			82.4%
210		/24			82.8%
211		/24			83.2%
212		/24			83.5%
213		/24			83.9%
214		/24			84.3%
215		/24			84.7%
216		/24			85.1%
217		/24			85.5%
218		/24			85.9%
219		/24			86.3%
220		/24			86.7%
221		/24			87.1%
222		/24			87.5%
223		/24			87.8%
224		/24			88.2%
225		/24			88.6%
226		/24			89%
227		/24			89.4%
228		/24			89.8%
229		/24			90.2%
230		/24			90.6%
231		/24			91%
232		/24			91.4%
233		/24			91.7%
234		/24			92.1%
235		/24			92.5%
236		/24			92.9%
237		/24			93.3%
238		/24			93.7%
239		/24			94.1%
240		/24			94.5%
241		/24			94.9%
242		/24			95.3%
243		/24			95.7%
244		/24			96%
245		/24			96.4%
246		/24			96.8%
247		/24			97.2%
248		/24			97.6%
249		/24			98%
250		/24			98.4%
251		/24			98.8%
252		/24			99.2%
253		/24			99.6%
254		/24			100%
Total Average Utilization		75%
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