Can Inverter interfere with working of Switch and ADSL router?

By rjkothari
May 13, 2007
  1. Hi,

    I'm having a peculiar problem. I've setup a small home network with 2 pcs (winxp). They are connected by a cat5 cable to a 8 port dlink 1008d switch. When cat5 cable connection is done - winxp shows 100 mpbs connection.

    And a ADSL router (make: dlink 502T adsl2+) is connected to one port of the switch. They are all physically placed next to a 800 VA Su-kam inverter with 190 VA lead-acid battery. They all are placed at a height of about 6.5 ft on a wooden platform in a passage to the bedroom.

    Below this wooden platform is the home's MCBS (miniature circuit breakers) 12+1 (big one). Each one is meant for a different circuit.

    I've noticed that in this config ping from one pc to another looses between 50 to 95% packets. Router lights are 'on' properly.

    adsl router worked for a while (half a day) when installed in this config but subsesquently even ADSL router's ADSL light and PPOE light does not light up i.e., I do not get ADSL's internet connection. When the PCs are connected directly to the ADSL router (without going thru the switch) - router's internet conection (ADSL light) does not work but ping is showing a perfect connection i.e., 100% packets are recd and sent by each PC.

    When ADSL is tested separately - in a place about 10 feet away from this place - it works perfectly. I've not tried using it through the switch.

    this Switch - when I tested at my office - it is working perfectly.

    Could it be that electrical interference from the inverter and/or mcb could be causing the switch and adsl router to loose packets and not give reliable connection?

    Rajesh Kothari
  2. jobeard

    jobeard TS Ambassador Posts: 9,158   +599

    I read you to say you are wired thusly;

    flip the switch/router locations to be

    You need the NAT feature of the router to control the IP addresses of all devices.
    With the switch in your current location, you can have all kinds of conflicts.

    As to your question re the inverter; A good device will have a UL and FCC rating
    on the tag and these will identify the spurious radiation limits of
    the device.

    Your CAT5 cables should be ok. CAT5 is UTP (unshielded Twisted Pair) but is the foundation for historic Ethernet.

    If it is an issue, go to cat5e or cat6 for those cables nearest the inverter.
    see this reference for cable differences

    There is a shielded CAT7 cable, but it is NOT RJ45 compatible :(

    EMI stands for Electro-Magnetic Interference. It is potentially harmful to your communications system because it can lead to signal loss and degrade the overall performance of high-speed, CAT5e cabling. EMI is interference in signal transmission or reception and is caused by the radiation of electrical or magnetic fields which are present near power cables, heavy machinery, or fluorescent lighting.

    Avoiding EMI is as simple as not laying your network cable within 12" of electrical cable, or if needed switching from UTP to more expensive shielded cable.
  3. rjkothari

    rjkothari TS Rookie Topic Starter

    May be I did not write well but current config is exactly same as what you have suggested viz. PCs-->Switch(Dlink 1008D)-->ADSL Modem+Router (Dlink 502T ADSL2+). Dlink 502T has ADSL Modem and Internet Router (with 1 ethernet port) in one piece. This port is connected to the switch using a cat5 cross cable.

    Each PC has been assigned ip addresses manually viz. 192.168.1.x (x=2 onwards). Dlink ADSL modem+router has ip address PCs have gateway= and subnet mask:

    Very similar configuration is working fine in my office network for years.

    Inverter is from a reputed and largest selling brand in India with CE, UL, ISO-9001 and 14001 certification.

    I forgot to mention that Phone line coming out from the ADSL modem+Router is going in to a 3x8 line EPABX located in the same setup. It's one of the 3 external telephone lines of the EPABX. Voice connections on the EPABX are fine.

    Funny thing is that if I remove switch from the setup and connect a particular cat5 cable to the ADSL Modem+Router directly - I get 100% ping response e.g., PING (from a PC with IP and default gateway Once in the beginning through this method I could get the ADSL connection and worked for half a day. But after that half a day connection - I could not make even this ADSL connection i.e., the ADSL and PPOE lights would not become 'on'. Admin would say that 'DSL line disconnected'.

    Surprising thing is that when PING is done from a PC to the ADSL Modem+Router with switch inbetween them -about 50 to 90% packets are lost. In this situation - ping from one PC to another also shows similar statistics. When checked using netstat -s -it shows lot of packets with address errors.

    Any suggestions?
  4. jobeard

    jobeard TS Ambassador Posts: 9,158   +599

    Your wired correctly then :) but use a standard cat5 cable; there's no need for the crossover type.
    looks correct, but personally, I would use the DHCP option and forget
    manual configuration -- but that's your choice and it SHOULD work.
    hum; nasty! try the standard cable as noted above. Ping inside your lan MUST
    be 100% reliable, so your symptom (and particularly when you disconnect
    the switch) points the finger at a BAD SWITCH :(
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