Cisco Systems IPMUX-1E Manual De Usuario

Chapter 1  Introduction 

IPmux-1/1E Installation and Operation Manual 

1-22  

Functional Description

The maximum Ethernet throughput in dynamic CAS mode is calculated by: 

[(

8000

) x ((payload+ 4) x TS) + 4 + frame overhead] x 8 bits 

•  where frame overhead is 46 bytes, including MAC, LLC, IP, and UFP layers 
•  where TS = number of configured time slots 
•  where payload = number of active time slot bytes per frame (24 to 64) 

 

The frame overhead does not include:  
•  Preamble field: 7 bytes 
•  SFD field: 1 byte 
•  Interframe gap: 12 bytes 
•  VLAN field (when used): 4 bytes. 

 

Configuring the packet delay and the number of time slots controls the Ethernet 
throughput. The range of the packet delay is 3 to 127 msec. 
A large number of time slots and a long packet delay can surpass the maximum 
Ethernet frame size.  
The maximum Ethernet throughput in CESoIP mode is calculated by: 

[(

1000

) x ((

8

) x TS) + 12 + frame overhead] x 8 bits 

•  where frame overhead is 46 bytes, including MAC, LLC, IP, and UFP layers 
•  where TS = number of configured time slots:  

 

for an unframed E1 interface = 32 

 

for an unframed E1 interface = 24 

•  where packet delay = 3 to 127.  

The voice path round-trip delay is a function of all connections and network 
parameters. The calculation for E1/T1 in each connection mode is described in the 
following sections.