Latency Fluctuation Issue

Alb3rt · 10-03-2010, 18:04

Hi Folks,

This is my first post on your forum, and I must say, very impressed by the community spirit on here.

I have a problem that I've trawled around the forum to see if there is a clear match but not really gotten one so here goes.

I have a 10Mb VM Service, with an Ambit Cable Modem and a DLINK DIR-615 router.

I route from my LAN to my gateway router/ firewall (DLINK DIR-615 recently supplied by VM to replace a Netgear that they told me was the cause of this problem). PC on LAN ---> DLINK 192.168.25.1 (changed from default) ---> 10.129.8.1 ---> Onwards to my destination.

Q1) What device is 10.129.8.1?

The first hop from my router to 10.129.8.1 can vary from 2ms up to 1100ms+ and it's happening at various times of day nothing specific. It can fluctuate in seconds and drop back down to 5 - 10ms.

Q2) Can anyone see a problem with this traceroute?

I see DNS..ok, traces right to the destination...ok Hop from my router to 10.129.8.1.. Aweful. See the last few hops of the traceroute, seems to have cleared up and we're ok again so the issue has gone even by the time this traceroute was complete.

tracert www.google.com

Tracing route to www-tmmdi.l.google.com [216.239.59.103]
over a maximum of 30 hops:

1 1 ms 1 ms 1 ms 192.168.25.1
2 566 ms 516 ms 634 ms 10.129.8.1
3 513 ms 446 ms 247 ms glfd-cam-1a-v101.network.virginmedia.net [80.4.3
0.5]
4 213 ms 190 ms 150 ms glfd-core-1a-ge-012-0.network.virginmedia.net [1
95.182.178.29]
5 9 ms 8 ms 11 ms glfd-bb-1a-ge-200-0.network.virginmedia.net [213
.105.175.85]
6 33 ms 87 ms 9 ms glfd-bb-1b-ae0-0.network.virginmedia.net [213.10
5.172.6]
7 32 ms 12 ms 25 ms manc-bb-1a-ae3-0.network.virginmedia.net [213.10
5.175.145]
8 37 ms 34 ms 20 ms manc-bb-1b-ae0-0.network.virginmedia.net [62.253
.187.178]
9 51 ms 42 ms 54 ms tele-ic-3-ae0-0.network.virginmedia.net [212.43.
163.70]
10 20 ms 33 ms 22 ms 158-14-250-212.static.virginmedia.com [212.250.1
4.158]
11 246 ms 459 ms 514 ms 209.85.252.76
12 564 ms 512 ms 601 ms 209.85.251.190
13 709 ms 533 ms 447 ms 209.85.240.158
14 45 ms 53 ms 71 ms 216.239.49.114
15 61 ms 50 ms 128 ms 66.249.95.169
16 70 ms 32 ms 28 ms gv-in-f103.1e100.net [216.239.59.103]

I have one PC on the network as I do this (normally 2 and an iPhone), it has just been scanned by SpyBot and I've done a full AV scan. I checked my open connections and they are minimal so I can't think there are any nasties using up my bandwidth. The PC is wired and not wireless so the latency should be minimal. Drivers are all up to day and I never get connections dropping on the LAN to the router.

Cable Modem Output:

Cable Modem Information
Cable Modem : DOCSIS 1.0/1.1/2.0 Compliant
MAC Address : Removed
Serial Number : Removed
Boot Code Version : 1.1.2c
Software Version : 2.111.1002
Hardware Version : 1.9

Cable Modem Status
Item Status Comments
Acquire a Downstream Channel 402750000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational

Cable Modem Downstream
Downstream Lock : Locked
Downstream Channel Id : 4
Downstream Frequency : 402750000 Hz
Downstream Modulation : QAM256
Downstream Symbol Rate : 5360.537 Ksym/sec
Downstream Interleave Depth : taps32Increment4
Downstream Receive Power Level : 13.1 dBmV
Downstream SNR : 42.5 dB

Cable Modem Upstream
Upstream Lock : Locked
Upstream Channel ID : 1
Upstream Frequency : 25800000 Hz
Upstream Modulation : QPSK
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 46.0 dBmV
Upstream Mini-Slot Size : 2

Cable Modem Upstream Burst

Req

Init Maint

Per Maint

Short Data

Long Data

(1)

(3)

(4)

(5)

(6)
Modulation Type QPSK QPSK QPSK QPSK QPSK
Differential Encoding Off Off Off Off Off
Preamble Length 64 128 128 100 80
Preamble Value Offset 396 6 6 396 396
FEC Error Correction (T) 0 5 5 3 9
FEC Codeword Information Bytes (k) 16 34 34 78 232
Scrambler Seed 338 338 338 338 338
Maximum Burst Size 0 0 0 35 254
Guard Time Size 8 48 48 25 134
Last Codeword Length Fixed Fixed Fixed Short Short
Scrambler on/off On On On On On

Cable Modem Operation Configuration
Network Access : Allowed
Maximum Downstream Data Rate : 10240000
Maximum Upstream Data Rate : 512000
Maximum Upstream Channel Burst : 1600
Maximum Number of CPEs : 1
Modem Capability : Concatenation Enabled, Fragametation Enabled, PHS Enabled

So the 10Mb/512Kb setup seems fine but Q3) I know nothing about all these settings so do they look right for my service?

If I have missed anything or you need to know more to help me, let me know, I appreciate any time anyone spends reading this and helping.

Thanks,

Albert

Welshchris · 10-03-2010, 18:46

ur downstream power level is way to high..

U need a tech to sort it, give faults a ring on 151 from Virgin phone or post on the Broadband faults newsgroup.

Alb3rt · 11-03-2010, 09:59

Thanks for the reply mate, what part of the modem output tells you that? Just curious. I'll look to raise a call today.