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justin
..needs sleep
Australian
join:1999-05-28
kudos:15
Reviews:
·iiNet

Cable modem flapping..

My cable modem (RCA) flaps. This is despite several tech visits now, and rewiring (3 times)..

70% of support people don't seem to know how to even check the flap counter (which seems to be stored upstream somewhere) and blame every other possible thing (bad power .. blah blah).

Thing is, the flapping has started in the last few weeks and someone else in the same building has the same problem starting the same time meaning I am suspicious of changes in the area now.

The last tech who was here was on the phone back to mission control and mentioned something about a 'recent frequency change'.

The flapping is not noticeable unless you have a TCP connection up .. or you watch the modem lights and spot it .. but it kills telnet sessions and streams..

oh well, so thats my unhappy story. Flapping cable modem and no luck getting it fixed.

bobafett

join:2001-02-27
Clinton, NJ
The flap counter I'm familiar with is stored in the cmts. I think 'flap-list' is a cisco thing. Usually flapping modems are the result of return problems (noise, ingress, clipping)


hockeyfun1$
Down With Dc Exec
Premium
join:2000-11-26
New Hartford, NY
reply to justin
Here is a link on information about it if it will help:

»www.cisco.com/warp/public/109/cc···dr.shtml
--
Join Team Discovery and find the cure for cancer!


justin
..needs sleep
Australian
join:1999-05-28
kudos:15
Reviews:
·iiNet

reply to justin
Interesting.. right?

# jre1.3.1_02/bin/java -jar docsdiag.jar -cmmac 001095fffffe
DocsDiag v011209 Copyright 2001 Robin Walker rdhw@cam.ac.uk

RCA DCM215 Cable Modem serial no. 65726045346991, HW_Version 024 (03.0), SW_Version ST05.14.00, Bootloader_Ver 11.1, OS: PSOS 2.5.0

Downstream channel ID = 1
Downstream channel frequency = 759000000 Hz
Downstream received signal power = -4.3 dBmV
Upstream channel ID = 2
Upstream channel frequency = 18992000 Hz
QoS max upstream bandwidth = 800000 bps
QoS max downstream bandwidth = 1500000 bps
SigQu: Signal to Noise Ratio = 34.5 dB
Cable modem status = Operational
Upstream transmit signal power = 39.2 dBmV
Date and Time = 2002-02-15,20:45:54.00-03:00
Configuration filename = default.cm

EDIT - ALSO:

2002-01-20,17:12:54 EVENT_DOWNSTREAM_LOCK_CONDITION - FIFO Full Event indicates DS Lock Condition
2002-02-15,15:12:15 last event repeated 3 times, up to this date/time
2002-01-22,05:36:04 REBOOT_MAC_RNG_RSP_WAIT_TIMEOUT - KS_MSG_CLASS_TIMER msg of type MAC_RNG_RSP_WAIT_TIMEOUT
2002-02-06,17:06:16 last event repeated 5 times, up to this date/time
2002-01-22,06:06:24 Time of Day: Failure to obtain Response from Time of Day Server
2002-02-15,02:56:19 last event repeated 68 times, up to this date/time
2002-01-22,09:41:11 REBOOT_MAC_RNG_REQ_T4_TIMEOUT - T4 Timeout during Ranging Request
2002-02-15,19:55:27 last event repeated 172 times, up to this date/time

2002-01-22,17:01:27 REBOOT_MAC_UCD_WAIT_TIMEOUT - KS_MSG_CLASS_TIMER msg of type MAC_UCD_WAIT_TIMEOUT
2002-01-22,21:42:21 last event repeated 1 times, up to this date/time
2002-01-26,17:04:36 REBOOT_DHCP_UPDATE_FAIL1 - update_dhcp_state found current_dhcp_state = DHCP_ERROR
2002-02-01,06:04:50 last event repeated 2 times, up to this date/time
unset DHCP: Failure to recieve Offer Datagram from DHCP Server
unset last event repeated 36 times, up to this date/time
unset DHCP: Failure in DHCP algorithm
unset last event repeated 36 times, up to this date/time
unset EVENT_REGISTRATION_SUCCESS - Upstream Channel ID=
unset last event repeated 64 times, up to this date/time
2002-02-02,15:16:48 EVENT_general
2002-02-14,23:15:58 last event repeated -1 times, up to this date/time

this is the event log .. I think the bold part is my "flapping"...
[text was edited by author 2002-02-15 19:09:11]


hockeyfun1$
Down With Dc Exec
Premium
join:2000-11-26
New Hartford, NY

Hmm, capped.

Sounds like they are just putting them in too. I will have to check tomorrow and see what mine are in PA.

EDIT: What modem does the other person in the building have? Unless if it is a temp. problem, you could always try asking them for a new modem...
--
Join Team Discovery and find the cure for cancer!

[text was edited by author 2002-02-15 19:12:12]


justin
..needs sleep
Australian
join:1999-05-28
kudos:15
Reviews:
·iiNet
reply to justin
I am convinced now RCN is now oversold in my building/area

The above error message in the cable modem log, can be combined with this text from the Cisco site on this page:
»www.cisco.com/warp/public/109/cm···ine.html

quote:
A way to detect if a modem is constantly ranging is to use the show cable flap-list command.

Upstream utilization too high

If the upstream utilization is too high, or too many modems are connected to the same upstream, it is possible that some modems will not get the required bandwidth or transmit opportunities to fulfill their periodic ranging requirements, also resulting in a T4 timeout.

Experience teaches us that customers who wish to successfully deploy data over cable networks based upon the DOCSIS standard must take into account many factors for success. One fundamental point that will ensure success is keeping customer return domains within reason. Keeping the homes passed (HHP) per upstream port to a reasonable level can significantly improve deployment success, maintenance costs, and improve customer satisfaction. For best performance it is recommended that 2000 homes passed per fiber node with ~10% penetration yielding 200 subscribing cable modems per upstream port is a highly effective framework by which to deploy.



hockeyfun1$
Down With Dc Exec
Premium
join:2000-11-26
New Hartford, NY
Yeah, probably too many people running servers of whatever sort . How are your speeds?


justin
..needs sleep
Australian
join:1999-05-28
kudos:15
speeds are ok (typical rcn type ~1000 or so). I think although the area is not oversold bandwidth-wise, its oversold upstream frequency wise?


hockeyfun1$
Down With Dc Exec
Premium
join:2000-11-26
New Hartford, NY
Yeah, sounds like it could just be more people using the upstream bandwidth on your node...

I know sometimes when the upload is a little slower (like maybe 400 kbps), the download usually isn't affected as much - but still sometimes it can be. Last time I heard RCN offers 27 mbps download and 10 mbps upload per node. So it would leave a little more room for the download to not be slowed down as much.
--
Join Team Discovery and find the cure for cancer!


Roundboy
Premium
join:2000-10-04
Drexel Hill, PA
reply to hockeyfun1$
said by hockeyfun1:
Hmm, capped.

I thought everybody was capped at 1500/800?

Justin: I feel your pain... at least its only my phone service that goes out every couple of months... I would go postal if it was my modem going out....
--
»cliftonclassic.winocrossing.com

R.I.P Invader Zim


hockeyfun1$
Down With Dc Exec
Premium
join:2000-11-26
New Hartford, NY
The caps must have been something more recent.


Peter S

@mcgraw-hill.com
reply to justin
Justin -

I just came across this thread - My modem was just diagnosed with flapping also - I live in NYC in a building with 375 units. I've got an RF tech coming out next week to see what happens. Not only does my bandwidth die it also causes my linksys wireless hub to zone out. This is VERY frustrating.


justin
..needs sleep
Australian
join:1999-05-28
kudos:15
Reviews:
·iiNet
This is an old thread -- but, it seems like an RCN problem.
They did fix it for a while (they did major work - or so they said) but shortly before I moved out it was back again although much milder.

I also had the wifi problems as well. Maybe we were in the same building mine was 300 mercer st..