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Massive Packet Loss

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by mjfarina, Apr 26, 2005.

  1. mjfarina

    mjfarina Network Guru Member

    In testing my connection, I have come to relize the WRV54G suffers from massive packet loss.

    Due to slow connection problems, I've been running some reports on broadbandreports.com. Basically after about 3 days of testing, I found a few issues.

    1) My linksys BEFCMU10 version 2 cable modem cuts my upload speed by over 10x when it's hot.

    2) My WRV54G looses about 28% of my packets.

    The heat thing was easy to fix...I opened the cabinet, and bingo speed jumps up. I need to find a way to activly cool the cabinet so that it can remain closed and fast.

    The packet loss is a totally different issue. If I take the router (WRV54G) out of the loop, and run the same line test I see 0% on my packet loss. I play a lot of online games, and I really need to fix the packet loss issue so that I can reduce my latency. Does anyone have a suggestion??

    Loss at 56byte pkts: 28%
    Loss at 1000byte pkts: 28%

  2. ipcdmatt

    ipcdmatt Network Guru Member

    Hi , ..

    This may be of some assistance or maybe not but you can consider the following:

    In terms of 1) Modem Overheat (Dont know your modem specifics but ...)

    Check orientation of modem, Vertical or Horizontal Mounting, Heat Flow may be a factor, is there an grate of sorts for warm air to escape (heat rises) , it may be intended to run vertically. Some speedstreams are known for thjs issue.

    If not then after it has been running for some time open the unit up and check for Hot spots( Finger Test or Meter with Thermocouple), look for the main chip, the biggest nastiest looking, king of the hill. You may be able to adapt a Chip Cooler (heatsink) or heatsink/fan combo, like those used on a typical PC, like a VGA chipset cooler or maybe a Northbridge Chip Cooler, form factor permitting.
    See your local PC store, Tiger Direct or something. (They have a kit for about 10$ with various heatsinks)

    As far as Packet loss... do node to node tests to isolate, Google for
    Dr. TCP and other related help pages for packet loss/MTU tweaking.

    Note: between a known troubled span, if you have control over media type, Like a NIC card on a PC, try changing from Auto Detect , hard code it downwards and retry, ... like 10 BT full duplex.

    Hope this leads to something.
  3. ipcdmatt

    ipcdmatt Network Guru Member

    ******** IMPORTANT ****************************

    In my prior post, I mentioned the finger test for checking for hot spots, .., this is very general and you are briefly touching the non-metallic parts of the top of the chip, if its hot to the touch or you cant leave your finger there then it may be the target of your attention or the added heatsink.

    It may also be that you have a defective unit with a thermal breakdown condition.......

    BUT most important, ....DISCONNECT THE POWER before doing this and watch out for metallic contacts which may have a stored charge even after power removal.

    Perform Test right after removing power as it may cool rapidly.

  4. mjfarina

    mjfarina Network Guru Member

    Using Broadband forums I see this when the router is plugged in...

    Broadband Forums Result

    Even after using DrTCP to turn "selective Acks" on, I don't see any help with the packet loss.

    0% to 28% with no-router to router seems like a huge jump to me? What do you guys thing?

    Thanks for the cooling suggestions =). I've got that one pretty much taken care of =).
  5. TazUk

    TazUk Network Guru Member

    Just ran the test myself and get exactly the same results :?

    Could be a bug in their test I suppose.
  6. mjfarina

    mjfarina Network Guru Member

    Knowing Linksys, it's most likely a bug in their hardware =). Is it possible to flash this router with other Linksys firmware? I guess that's another question, maybe I'll post it as a new topic =).

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