Cisco Systems IPMUX-1E Ethernet Throughput in Dynamic CAS Mode, Unstructured, Structured

IPmux-1/1EInstallation and Operation Manual Chapter 1 Introduction

Frame/second =

Unframed: 5447/n for a full E1 4107/n for a full T1

Framed: 8000 x k/(46.875 x n)

Where k = number of assigned timeslots

Where n = TDM bytes/frame 48

The maximum Ethernet throughput in static mode is calculated by:

Unstructured		data
			
		64748	
		8000 * TS 		* 8 bits
(VLAN + frame overhead + payload) * 		47 * n	
1444444244444443			
frame size			
			
Structured					pointer
		data				CAS		
					64748	64748		
		64748			8000 * TS	 TS		
		8000 * TS +			(47 * 8) - 1	+ 500 * 	
						 2		
(VLAN + frame overhead + payload) * 									* 8 bits
					47 * n
1444444244444443								
frame size								
								
								

•where VLAN is an optional field: if enabled it adds 4 bytes to the frame overhead

•where payload = number of TDM bytes in frame, (48, 96, 144, 192, … 384)

•where frame overhead = size of 46 bytes, include MAC, LLC, IP and UDP layer

•where CAS is signaling (note: for structured mode only)

•where TS is number of configured time slots.

The result in both the equations is in bits per second [bps].

Ethernet Throughput in Dynamic CAS Mode

Configuring the active time slot bytes parameter can reduce Ethernet throughput. This parameter controls the number of TCM bytes encapsulated per time slot in a frame. The range is 24 to 64 bytes.

A large number of time slots and a large active time slot bytes size can surpass the maximum Ethernet frame size.

In dynamic CAS mode the throughput is variable, depending on the active time slots as defined by the ABCD CAS bits.

Functional Description 1-21