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Circuit Emulation over IP Bandwidth Requirements

I'm trying to size the bandwidth necessary to support T1s emulated over IP using the NM-CEM-4TE1 modules. Obviously the T1 is 1.5Mb. Without using payload and/or header compression, what does this translate to on the IP side?

Thanks in advance!


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Re: Circuit Emulation over IP Bandwidth Requirements

Hello Tom,

the IP overhead depends on your choice for the payload size.

The emulated circuit is sampled and the samples become the payload of an UDP/IP packet in blocks decided by the payload size parameters.

if using payload size = 512 byte

the UDP/IP packet will be 512+20+8 bytes

if you use 40 bytes of payload the overhead effect is much bigger

78 bytes towards 40 bytes and this will take almost 3 Mbps on wire.

Payload Size

Payload size is the number of bytes put into each IP packet. This parameter impacts packetization delay and efficiency. Configure a high payload size to increase packetization delay and efficiency. A smaller payload size reduces packetization delay and efficiency.


you can decrease the required BW if you use payload compression or to double it if you choice to use data protection.

of course it is wise to build the CEM tunnel using loopbacks interfaces' ip addresses.

Once you make your choices you can provide QoS resources on the ip path to the CEM tunnel.

Hope to help