Netgate SG-1000 microFirewall

Author Topic: LAN Traffic is Less Than WAN Traffic  (Read 2801 times)

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Offline simpat1zq

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LAN Traffic is Less Than WAN Traffic
« on: December 26, 2005, 06:36:52 pm »
I was looking at the traffic graphs for the LAN and the WAN(my only 2 interfaces), and noticed that WAN Traffic Out was always about 20kbps higher than the LAN Traffic In at about 100kbps. Is this normal? And if it is normal, am I correct in assuming that it's because the LAN traffic is coming in via layer 2(switched), and the WAN traffic is leaving via layer 3(routed) so it has more overhead? And if that's the case, do the layer 3 headers really take up that much more space?

thx

Offline billm

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Re: LAN Traffic is Less Than WAN Traffic
« Reply #1 on: December 29, 2005, 01:35:23 am »
I was looking at the traffic graphs for the LAN and the WAN(my only 2 interfaces), and noticed that WAN Traffic Out was always about 20kbps higher than the LAN Traffic In at about 100kbps. Is this normal? And if it is normal, am I correct in assuming that it's because the LAN traffic is coming in via layer 2(switched), and the WAN traffic is leaving via layer 3(routed) so it has more overhead? And if that's the case, do the layer 3 headers really take up that much more space?

thx

You need to read up on the OSI model a little more (http://en.wikipedia.org/wiki/OSI_model).  Regardless, it sounds like your WAN connection is PPPOE, this will result in another layer 3 encapsulation on top of your IP layer.  This is one of the reasons most internet pipe benchmark sites will tell you that there's about a 20% overhead on your DSL connection.

--Bill

PS. that 20% is NOT the same 20% that the shaper removes - keep that in mind ;)
pfSense core developer
blog - http://www.ucsecurity.com/
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Offline simpat1zq

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Re: LAN Traffic is Less Than WAN Traffic
« Reply #2 on: December 29, 2005, 07:59:16 am »
I know the OSI model pretty well(layer 4 and lower). I just wanted to see if I understood this particular situation correctly.