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RV042 and Selective ACKs blocking

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by Toxic, Apr 24, 2006.

  1. Toxic

    Toxic Administrator Staff Member

    I was running some speed tests yesterday and noticed the WAN was slightly slower in performace then the WRTSL54GS.

    I then went to http://www.dslreports.com/tweaks and ran some tests

    at the end of the test the results showed

    "Turn on Selective Acks" though effiency was 99%

    i checked the setting with the DRTCP utility. it reported it was enabled. to test this i plugged in the WRTSL54GS and low and behold the Selective Acks were enabled when i ran the test again.

    I ran this test 3-4 times to confirm the findings.

    can anyone else confirm the RV042 and even other RVxxx units are blocking Selective Acks feature from the Operating system.

    this therefore slows the throughput down.
     
  2. TazUk

    TazUk Network Guru Member

    I pretty sure that's the case with the WRV54G, although I haven't checked since the last firmware update.
     
  3. skorell

    skorell Network Guru Member

    I can confirm that my RV042 (1.3.7.4) also seems to disable selective acks. My RV042 Wan throughput maxes out at around 3-4Mbps on my 9/1 Cox connection. I have since hooked back up my WRT54GS and speeds have returned to rated spec. The RV042 should definently be able to handle much greater throughput, which makes me believe the firmware might be the limiting factor. I have worked with Linksys tech. support on several ocassions without success on resolving this issue. I have tried all the common troubleshooting step to maximize Wan throughput, but they make little to no difference.
     
  4. d__l

    d__l Network Guru Member

    skorell, if you disable Selective ACKs in your computer's OS and then use your WRT54GS in a speed test, are your speed tests just as slow? I don't think the loss of Selective ACKs will cause as much slowdown as you are seeing with the RV082. But I could be wrong. :)
     
  5. Toxic

    Toxic Administrator Staff Member

    Selective acks can affect throuput is traffic is congested and over long distance where packet loss can happen. selective acks is recommended to be enabled nowadays since broadband speeds are faster and faster and RWIN sizes are larger now.

    skorell i have notified key linksys reps (state side and EU Side) of this issue now and they are looking into it, howver it would not hurt anyone from contacting linksys and making escalating the issue more.

    if other linksys products allow them, then so should the rv042.

    can anyone with a RV016 or RV082 confirm these findings as well?
     
  6. YeOldeStonecat

    YeOldeStonecat Network Guru Member

    Can confirm the RV082 is..using 1.3.2....I'll check from our office tomorrow as our 082 is still on the older firmware.

    However I don't believe it to really have much impact at all on throughput....all the RV0 units I've setup so far are able to peg the WAN connection...I've been able to test up to 10 megs...

    ..actually in about a month I may have the chance to test of a full DS3...45 megs.

    I'll as Philip from Speedguide.Net about the selective ack on the router...
     
  7. Toxic

    Toxic Administrator Staff Member

    I can confirm one thing the RV042's MTU set to Auto is only 576

    MTU to Auto:

    ixp1
    Link encap:Ethernet HWaddr 00:12:17:XX:XX:XX
    inet addr:XX.XX.XX.XX Bcast:XX.XX.XX.XXX Mask:255.255.252.0
    UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:576 Metric:1
    RX packets:4432 errors:0 dropped:0 overruns:0 frame:0
    TX packets:3501 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:100
    RX bytes:1660070 (1.5 Mb) TX bytes:540177 (527.5 kb)


    MTU to 1500

    ixp1
    Link encap:Ethernet HWaddr 00:12:17:XX:XX:XX
    inet addr:XX.XX.XX.XX Bcast:XX.XX.XX.XXX Mask:255.255.252.0
    UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
    RX packets:4432 errors:0 dropped:0 overruns:0 frame:0
    TX packets:3501 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:100
    RX bytes:1660070 (1.5 Mb) TX bytes:540177 (527.5 kb)

    make sure it is NOT set to Auto.
     
  8. YeOldeStonecat

    YeOldeStonecat Network Guru Member

    Yes...the 082 models did that also...even 3x firmware versions ago. I mentioned it a few times...and it's why I always state to manually set MTU...always do this regardless of what brand/make/model router I'm installing.
     
  9. Toxic

    Toxic Administrator Staff Member

    i just chased the issue of Selective Acks up again with linksys. they have now confirmed the issue has been fixed and firmware is being tested at present.

    I have also asked for MTU Auto size to be set to 1500 (not 576) and asking confirmation about the state of the RV082 firmware in relattion to the same issue the RV042 has.
     

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