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   Newsgroups: comp.os.linux.networking,alt.comp.networking.firewal   
   s,alt.comp.networking.routers,alt.os.linux.debian,alt.os.linux.ubuntu   
   From: Mike Lovell    
   Subject: iptables NAT forwarding adding 75-100ms   
   Organization: home.b0h0.com   
   Followup-To: comp.os.linux.networking   
   User-Agent: slrn/pre1.0.0-18 (Linux)   
   Message-ID:    
   Date: Sun, 29 Apr 2012 17:42:47 -0500   
   Lines: 39   
   NNTP-Posting-Host: fa1bc2e5.stealthnews.com   
   X-Trace: DXC=06:]mQVV wan   
   eth0 -> lan   
      
   The relevant forwarding/NAT rules are:   
      
      
   #iptables -A FORWARD -i wan0 -o eth0 -m state --state RELATED,ESTABLISHED -j   
   ACCEPT   
   #iptables -A FORWARD -i eth0 -o wan0 -j ACCEPT   
      
   #iptables -t nat -A POSTROUTING  -o wan0 -j MASQUERADE   
      
      
   So pretty standard boring NAT.   
      
   Lag is occurring (between 75ms and 100ms) on all forwarding rules.  Apart   
   from the lag they function fine (no connectivity issues).   
      
      
   Ping: LAN Machine -> Debian Router = ~0.7ms   
   Ping: Debian Router -> Google = ~20ms   
   Ping: LAN Machine -> Google = ~121ms !!!   
      
      
   The Debian server has plenty of free RAM, the load is showing as low,   
   it's (at this time) entirely dedicated to routing - Why is it   
   introducing 100ms of lag into forwarded traffic???   
      
   Anyone else seen similar to this???   
      
      
   I get great speed from LAN machines, just high latency.   
      
    ~ Mike   
   --- Platinum Xpress/Win/WINServer v3.0pr5   
    * Origin: Omicron Theta BBS (1:261/20)