Intermitant Cable and Router drop

[t1mmy123456]

I will be using the internet and my connection will go to zero bandwidth. The only thing I can do is pull the power on the router and cable modem. Then I have to go to the router setup and do a DHCP IP renew. Finally my connection will work until it happens again. It usually happens once a day.

I have Comcast, RCA DCM305 Cable modem, Linksys BEFSK41. I am trying to figure out if I need to have the utility replace the modem or replace my router. Or maybe it is my cables?

Thanks for your help.

timmy123456

This is what is on the cable modem:

Foward Path:
Signal: 632.983 Mhz
SNR: 35.6 db
RSS: -10.3 dBmV
Mirco-Reflections: 21 dBc
Mod: 256 QAM

Return Path:
Connection: Aquired
Frequency: 21 Mhz
Power Level: 45.2 dBmV
Channel: 3
mod: 3

Log:
Event Description First Time Last Time Counts
No Ranging Response received - T3 time-out 14:25:36 - 07/10/2006 02:32:38 - 08/13/2006 5
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing 06:23:35 - 07/11/2006 20:31:05 - 09/29/2006 289
SYNC Timing Synchronization failure - Failed to acquire FEC framing 06:23:35 - 07/11/2006 20:31:05 - 09/29/2006 285
SYNC Timing Synchronization failure, Acquired FEC framing - Failed to acquire MPEG2 Sync 06:23:35 - 07/11/2006 20:31:05 - 09/29/2006 285
Started Unicast Maintenance Ranging - No Response received - T3 time-out 12:46:52 - 07/23/2006 18:45:04 - 09/28/2006 165
SYNC Timing Synchronization failure - Loss of Sync 17:04:58 - 07/25/2006 20:31:06 - 09/29/2006 21
EVENT_COLD_START [ST24.1B.03 1.1s_ST24_1B_03_raw.img] - The Cable Modem was powered off and back on 19:10:04 - 09/29/2006 19:10:04 - 09/29/2006 1
Map Reject - Downstream Traffic Flow Not Mapped to BPI+ SAID (EC=8) 19:10:05 - 09/29/2006 19:18:10 - 09/29/2006 3
Last Refresh: 21:18:21 - 09/29/2006

Test:
WEB100 Enabled Statics:
running 10s outbound test (client to server)...373.93Kb/s
running 10s inbound test (server to client)...6.17Mb/s

-------Web100 Details -----
Cable Modem
Full duplex
No network congestion
Good network cable(s)
Normal duplex operation

Web100 report
Round trip time =69.02 msec;Packet size = 1448;
There were 47 packets retransmitted, 943 duplicated acks receive
0 Sack Blocks received.
Connection stalled 1 time due to packett loss.
Connection was idle 0.3 s (3.0%) of the time.
Connection is receiver limited 83.26% of the time.
Connection is network limited 16.72% of the time.

[trogers]

Web100 report
Round trip time =69.02 msec;Packet size = 1448;
There were 47 packets retransmitted, 943 duplicated acks receive
0 Sack Blocks received.
Connection stalled 1 time due to packett loss.
Connection was idle 0.3 s (3.0%) of the time.
Connection is receiver limited 83.26% of the time.
Connection is network limited 16.72% of the time.

47 packets retransmitted!

You have to use elimination method to isolate the cause. I would first suspect the modem.

I would go borrow a modem from a friend and test my connection. If things remains the same I will return the modem and borrow a router...

That's the way to go to avoid spending unnecessary money.

[t1mmy123456]

I tested the connection three more times to see if I could get a better reading. This is what I came up across the board.

In the Web100 tests I received:
76.58 msec: Packet size =1448
No packet loss - but packets arrived out-of-order 14.43% of the time.
receiver = 97.43%
network = 2.74 %

[trogers]

This time, packets arrived out of order. The results of the tests shows problem in signal quality.

The usual first thing I would look at is possible electromagnetic interference on the modem from some nearby electrical device such as router, speakers or cordless phone.

The reason for this is that we only have 1-2 power outlets in a room and with the many electrical devices we use in our daily life, they tend to be placed near to each other.

[YeOldeStonecat]

Which model Linksys is it? There's a befsr and ta befsx..no befsk though.

Is MTU manually set to 1500 on the router?

[t1mmy123456]

You are correct it is the befsx41. Firmware 1.45.7

[t1mmy123456]

MTU is auto: cell set to 1500.

[t1mmy123456]

I moved somethings around. Moved my router away from my cable modem and power outlet strip.
Web100
Packets out of order 11.28% of the time.

The cable modem added this to the events list
EVENT_THOLD_MAX_ALERT Cable Modem converged to an upstream power, 53 dBmV, which is near the maximum. 14:14:22 - 09/30/2006 14:14:22 - 09/30/2006 1

[trogers]

Moved my router away from my cable modem and power outlet strip.

The modem is the Switch. Isolate it away from your router and the power outlet strip.

[t1mmy123456]

I decided to remove the router from the equation. I had one workstation and the cable/modem.

Web100 (5 out of 5 tests)
~4% packets out of order

I was looking at replacing the cables between this one workstation and the cable modem and testing agian, but at this point would you say it is the cable modem or a combined problem?

[trogers]

I am more inclined on the cable modem. If cables are faulty, usual symptoms are lost packets and higher latency rather than packets arriving out of order. Another possibility may be a fault in the NIC as this works in duplex mode with your modem.