Total BW vs number of interfaces

Forums Network Management Firewall, Traffic Shaping and Net Balancer Total BW vs number of interfaces

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    toying with QoS and my setup, i notice a curiosity, take this case for example:

    ADSL, 3Mbps/256Kbps assigned as ppp0, global BW set at 200kbps/184kbps M/G

    i have a station that’s dedicated to P2P traffic so i find it easier to shape and isolate using a dedicated interface to it: ETH02 to which i set the BW as 3000kbps/2200kbps

    And then i have the normal ETH0 for all the rest of the network with the usual queues for gaming, udp, ACK traffic, etc etc with BW set as 3000/2300

    With this setup i was able to shape P2P uplink traffic which otherwise wasn’t working at all even though the packets where being marked

    now this got me wondering, am i ADDING the BW here?(effectively setting 6mbps total), meaning shapers work on their own interface…

    so, what’s stopping the P2P PC from killing my download @3mbps when it only has one “low priority” download rule(which should be always end up gobling the BW).

    Is “low” priority a global or is evaluated per-interface?

    How does the system cope with a class that has high priority on one interface versus another one on low(in the same direction from the same source ppp0)?

    i’m worried that whilst this apparently solved my shaping issues with P2P i essentially shot myself in the foot by making all the rules for the main LAN moot


    Both your LAN interfaces have one egress point, which is ppp0. On ppp0 is where the QoS should be applied as it is the bottleneck of your network. So if you aggregate all the classes on ppp0 you get the prioritize of the packets.


    you’re talking about upstream traffic, which i have covered.

    I’m talking about downstream as i have two egress points and i want to know how each queue BW and priority compete between eachother or how do they interact in this case.

    (i.e. i set eth0 for 200 kbit guaranteed+max download for http and i start downloading @200kbps merrily. Then on ETH02 i set the same with 3Mbit which is the maximum rate of my modem, what happens now?, does the system realize it’s all coming from one point and priorize accordingly or all hell breaks loose and i get shitty performance?

    With the sum of the “global” bw for each ETH i’m exceeding the adsl total, but i can’t declare 50% for wach as that’ll kill my Bw for each interface.

    you get my point?


    You cannot prioritize your incoming traffic as it has already come to you. You prioritize outgoing traffic so that time sensitive packets get priority over not time sensitive packets. Plus that if you apply QoS on the ETH00 interfaces you may end up with useless interfaces due to starvation.

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