TGWB Configuration

The reliable multicast transmission was implemented as a function library called RML (Reliable Multicast Library) [#!rmcast_site!#]. When tgwb is started the user is prompted for configuration options, such as multicast address and port and whether or not the mcastproxy (see section ) program should be started. Another way to customize RML options is editing the configure file tgwb.conf, located at .tgwb directory in the user's home.

#Reliable Multicast Library configuration file

#Reliable Multicast Library version
RM_VERSION=1.0

#Transmission mode: 0 multicast (default), 1 unicast
TRANSMISSION_MODE=0

#Multicast or Unicast IP address to send data (destination IP)
DEST_IP=225.2.2.10

#Multicast or Unicast port to send data (destination port)
DEST_PORT=5151

#Time to live for the packets setting (1 indicates local network)
TTL=1

#Inter-packet sleep timer:
#Time between packet transmissions ( choose from 0 to 65535 microseconds)
MICROSLEEP=10

#Log file path - NULL disable logging (default)
LOG_FILE=NULL

#Random Timers Distribution: 0 uniform 1 exponential
TIMER_DISTRIBUTION=0

#Timer parameters
# Timers values are obtained in the intervals:
# (TIMER_PARAM_A*T,(TIMER_PARAM_A+TIMER_PARAM_B)*T)
#   for NAKs
# (TIMER_PARAM_C*T,(TIMER_PARAM_C+TIMER_PARAM_D)*T)
#   for wait for retransmitions
# (TIMER_PARAM_E*T,(TIMER_PARAM_C+TIMER_PARAM_F)*T)
#   for for retransmitions
# Where 
#  TIMER_PARAM_A, TIMER_PARAM_B, TIMER_PARAM_C,
#  TIMER_PARAM_D, TIMER_PARAM_E and
#  TIMER_PARAM_F are integer constants 
#  T is the estimated one-way delay to the senders
TIMER_PARAM_A=2
TIMER_PARAM_B=2
TIMER_PARAM_C=5
TIMER_PARAM_D=2
TIMER_PARAM_E=2
TIMER_PARAM_F=2

#Host related parameters and timers:
# Must contain exactly the following lines:
#   HOSTS_IDENTIFIED=0
#   DEFAULT <AVERAGE_ESTIMATED_DELAY>
#   host1   <ESTIMATED_ONE-WAY_DELAY_TO_host1>
#   host2   <ESTIMATED_ONE-WAY_DELAY_TO_host2>
#   ...
#   hostN   <ESTIMATED_ONE-WAY_DELAY_TO_hostN>
# If HOSTS_IDENTIFIED=0 then we will read only the DEFAULT
# estimated delay. 
HOSTS_IDENTIFIED=0
DEFAULT 300

#Max number of naks that can be sent for each packet. 100 (default)
MAX_NAK=100

# We will be able to retransmit the last MAX_MEMBER_CACHE_SIZE packets
# from each member of the multicast group, i.e., we will store the last
# MAX_MEMBER_CACHE_SIZE PACKETS from each member of the multicast group
# in the cache. 4000 (default)
#
# WARNING: if you set MAX_MEMBER_CACHE_SIZE to low values the protocol
# may fail!
#
MAX_MEMBER_CACHE_SIZE=4000 

#Enable support for new members 1 enabled (default), 0 disabled
NEW_MEMBER_SUPPORT=0

#Show transmission statistics: 0 disabled (default) 1 enabled
STATISTICS=0

#Time between transmission of refresh messages (seconds)
REFRESH_TIMER=10

#Loss simulation: 0 disabled (default) any float number > 0 enabled
#
# A note about loss simulation:                         
# When loss simulation is enabled (LOSS_PROB > 0) we always loose the
# first 10 received packets, and the first received data packet - 
# that is, the first burst of received packets.
# After that, packets are lost according to LOSS_PROB.
# Example: LOSS_PROB=30
# The first 10 received packets will be lost.  
# Then, 30% of the packets will be lost 
LOSS_PROB=0

# Time to wait, in microseconds, before leaving the multicast group.
LEAVE_GROUP_WAIT_TIME = 500000

# Size of the buffer of the receiver host
# (maximum size of a message that may be processed by the receiver host).
RCV_BUFFER_SIZE = 10000