Sub Interface Bandwidth

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Jun 13th, 2007
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How router allocate bandwidth for its subinterfaces?


For example, if an fastethernet interface has 4 sub-interfaces, how much bandwidth was allocated for each interface?

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Edison Ortiz Wed, 06/13/2007 - 07:53
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Subinterfaces are virtual interfaces. The bandwidth of the physical interface (the main interface) remains the same and it will be distributed evenly among subinterfaces.


It also depends on the queuing configured on the physical interface (fifo, fair-queuing, etc) on how the traffic would be handled....



smallrain_2 Wed, 06/13/2007 - 11:12
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Are you saying 2 sub-interfaces on fast ethernet port will have 50Mbps each?


Is there any way to allocate the bandwidth for sub-interfaces? For example, management vlan might need less bandwidth than Data VLAN.

Edison Ortiz Wed, 06/13/2007 - 11:16
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The bandwidth won't be limited to a specific ratio. If a subinterface is demanding 100Mbps and no other interface is demanding traffic, it will use it at 100%. If other interfaces are demanding traffic, it will try to balance out the traffic accordingly.


You can allocate bandwidth for specific networks by using any form of QoS.



http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hqos_c/index.htm


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