Insufficient ram

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Revision as of 02:09, 28 July 2009 by Phuzi0n (Talk | contribs)
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Introduction

Issues occur with routers that have only 8MB ram. DD-WRT includes several features even in micro builds but many of these features will cause the router to run out of ram on routers that only have 8MB ram. However, some devices that run micro builds do have more than 8MB ram; these devices should not easily run out of ram and can enable any of the included features.

These problems may occur directly after enabling a feature but often times may not occur until using the router with heavy P2P applications that cause the router to use ram that it normally wouldn't under low load. The router may only become 'slow' over time without crashing. Some symptoms can be:

  • Slow web-interface, or cannot connect at all to web interface
  • Slowing transfer of data, e.g. browsing, after a reboot
  • Not responding to ping
  • Router crash or rebooting

P2P Solution

Copied from Router Slowdown. After you have rebooted and turned off any heavy P2P applications:

  • Go to the Web Interface of the DD-WRT Device and log in
  • Go to 'Administration'
  • Go to 'Management'
  • Enter the following values at 'IP Filter Settings'
    • Maximum Ports: 1024
    • TCP Timeout (s): 90
    • UDP Timeout (s): 90
  • Save Settings and then Reboot Router

The above settings cause inactive TCP & UDP connections to be dropped after 90 seconds.

  • If you start getting frequent disconnections from an Instant Messenger program bump your TCP timeout up to 300 first.

Other Solutions

Due to the lack of RAM you must disable any non essential features. The common ram hogs are:

  • QoS - Only the default rules will consume high ram. Custom created rules use negligible ram.
  • Access Restrictions - Only the default rules will consume high ram. Custom created rules use negligible ram.
  • UPnP - This service makes port forwarding easier but not all programs support UPnP anyways. Custom created port forwarding rules use negligible ram.
  • ttraff Daemon - This service makes pretty traffic graphs.
  • Telnet - This service provides CLI access to configure your router. It can be disabled when you're not using it but make sure to have httpd enabled if you disable this.
  • HTTPD - Web GUI -- This service allows you to visit the router's address in your browser to configure it. It can be disabled when you're not using it but make sure to have telnet enabled if you disable this.


To disable HTTPD:

  • First, make sure Telnet is enabled. This way, it is possible to connect to the DD-WRT Device and turn the Web Interface back on when needed.
  • Navigate to the Administration page in the Web Interface and uncheck HTTP and HTTPS in the Web Access section. Apply your changes.
  • To finish disabling it, connect to the CLI and use the command 'killall httpd'. When starting the Web Interface on an as-needed basis, use the command 'httpd'.