Random IPs slow on some networks

I have an interesting (at least I think so) situation.

We just went to 32 IPs and found that some are reported slow from www.2wire.com speed tests. They are random and they are always slow (400K-600K) when tested. All the others are fast and are always fast (4-5Mb).

Now the question is why. The last number in the octet is 192-222. Between 198-215 (the only ones I have tested) - 198, 201, 203, 206, 209, 211, 212 and 214 always show as slow. differences in speed can't be related to the Internet (as far as I can see or all the addresses would do the same thing).

SBC (our DSL provider) was here and tested the speeds with the speed tests at Dslreports and found that all the address run at around 4.5Mb.

SBCs comment is that they can't trust 2wires numbers. I would agree if they weren't so consistant. He didn't seem to get that. Unless there was some algorithm or filter that would pull out random addresses (and always the same random) addresses, there has to be some explanation to this.

Here is the trace route to 2wire. I am curious as to the 13th hop. It is dcr2-loopback.... I don't know if that has anything to do with it, but I was curious as to whether this indicates anything.

[code:1]
Tracing route to www.2wire.com [216.52.29.100]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms 10.0.0.254
2 1 ms <1 ms <1 ms adsl-69-232-10-222.dsl.lsan03.pacbell.net [69.23
2.10.222]
3 10 ms 9 ms 9 ms 10.20.30.40
4 15 ms 9 ms 8 ms dist4-vlan50.lsanca.sbcglobal.net [64.161.163.21
3]
5 10 ms 8 ms 9 ms bb2-g3-0.lsanca.sbcglobal.net [67.116.100.166]
6 8 ms 9 ms 8 ms bb1-p6-0.lsan03.sbcglobal.net [151.164.191.161]

7 12 ms 9 ms 9 ms core1-p6-1.cranca.sbcglobal.net [151.164.241.210
]
8 10 ms 9 ms 13 ms bb1-p8-0.cranca.sbcglobal.net [151.164.40.94]
9 10 ms 10 ms 10 ms ex1-p15-0.eqlaca.sbcglobal.net [151.164.41.29]
10 10 ms 10 ms 10 ms bpr2-ge-2-1-0.LosAngelesEquinix.savvis.net [151.
164.248.214]
11 11 ms 10 ms 10 ms bpr1-ae0.LosAngelesEquinix.savvis.net [208.172.3
5.49]
12 * 11 ms 11 ms dcr1-so-4-2-0.LosAngeles.savvis.net [208.172.44.
105]
13 22 ms 22 ms 22 ms dcr2-loopback.SanFranciscosfo.savvis.net [206.24
.210.100]
14 21 ms 21 ms 21 ms bpr2-so-4-0-0.SanJoseEquinix.savvis.net [206.24.
211.78]
15 21 ms 21 ms 22 ms internap.SanJoseEquinix.savvis.net [208.173.55.3
0]
16 21 ms 22 ms 21 ms border1.ge0-0-bbnet2.sje.pnap.net [66.151.144.68
]
17 21 ms 21 ms 21 ms 2wire-2.border1.sje.pnap.net [66.151.145.218]
18 22 ms 21 ms 21 ms www.2wire.com [216.52.29.100]

Trace complete.
[/code:1]

That is wierd isn't it.
Are you using 2Wire as your ISP and using one of their boxes for the 'end'?

2wire is just a website ( www.2wire.com ). They happen to have a speed test, which just tests the speed it takes to load their page. They are pretty consistant, in their range. Below are the results of my test (very scientific). The speeds are all plus/minus about 150K for the slow speeds and about plus/minus 400K on the fast speeds. Also these test were run on my old Laptop (200mhz) and 2300K seems about the fastests it will go. That actually explained why our firewall was running at about 2100. It is a Winnt4 about 5 years old, so is probably a 200mhz machine also. When I run with our other laptop or the new machine, the fast speed is around 4-6MB.

But the important thing to notice is that if the last three bits are 111 or 000, they are fast. Also, the IPs that are fast are always fast, the ones that are slow are always slow. I could accept the SBC rep that you can't trust 2wires number, except for this fact. I would expect that each IPs numbers would be all over the place if you couldn't trust 2wire, but just isn't the case.

These tests were run outide of the firewall directly on the DSL Router, using the same laptop. The other laptop gave us the same results (except 4MB instead of 2MB). All our internal machines get the fast speed and they are on a fast IP also (they use the same IP, as you mentioned).

I agree that being the same block they should get the same speed. For DSL Reports they do. Our other block of 8 gave us the same results - 3 slow and 2 fast.


[code:1]
IP (last Octet) Speed (K) Speed Bits
198 400 slow 0110
199 2000 fast 0111 <--
200 4500 fast 1000 <--
201 500 slow 1001
202 2100 fast 1010
203 500 slow 1011
204 2100 fast 1100
205 2100 fast 1101
206 500 slow 1110
207 2100 fast 1111 <--
208 2000 fast 10000 <--
209 550 slow 10001
210 2100 fast 10010
211 500 slow 10011
212 500 slow 10100
213 2100 fast 10101
214 500 slow 10110
215 2100 fast 10111 <--
216 2100 fast 11000 <--
[/code:1]