Technical data

4. Packages
This is extremely important with asymetric connections (up- and downstream band-
widths differ) like used in most DSL lines. Those most likely have a small upstream
that tends to reach its maximum rather fast. If ACK packets are normally queued
this may end in the data server delaying its transaction to wait for ACK packets to
come in. This results in download rates lower than they could be.
So ACK packets have to bypass the “normal” packets in order to get to the data
server as fast as possible. How to combine this option in a meaningful way with a
class is explained in the examples.
ICMP Ping packets (Protocol ICMP)
Ping packets are used to measure time a packet takes to get from A to B. To take
influence on this value give ping packets a higher priority. This does not influence
ping times for online games.
IGMP IGMP-Pakete (Protokoll IGMP)
If using IP-TV it makes sense to filter and priorize IGMP packets.
TCPSMALL Small TCP Packets
By using this filter outgoing HTTP(s)-Requests can be filtered and priorized. A
combination with a destination port is possible and makes sense. Approx. size of
this TCP packets is 800 Byte max.
TCP TCP packets (Protocol TCP)
Only packets using protocol TCP are filtered.
UDP UDP packets (Protocol UDP)
Only packets using protocol UDP are filtered.
TOS* Type of Service
An application can set one of four TOS bits for each packet transmitted. This
specifies the intended handling for those packets. For example SSH can set TOS-
Minimum-Delay for sending in- and output and TOS-Maximum-Troughput for send-
ing files. Linux/Unix programs use these bits more often than Windows programs.
A firewall can set TOS bits for certain packets as well. In the end it all depends on
routers in the transport chain to honour TOS bits or not. Only TOS bits Minimum-
Delay and Maximum-Throughput are really important for fli4l.
TOSMD - TOS Minimum-Delay Used for services that need packets to be trans-
ferred without time delays. It is recommended to use this TOS bit for FTP
(control data), Telnet and SSH.
TOSMT - TOS Maximum-Troughput Used for services that need big amounts of
data to be transferred with high speed. It is recommended to use this TOS bit
for FTP data and WWW.
TOSMR - TOS Maximum-Reliability Used to ensure that data reaches its target
without being resent. Recommended use for this TOS bit is SNMP and DNS.
TOSMC - TOS Minimum-Cost Used to minimize costs for transferring data. Rec-
ommended use for this TOS bit is NNTP and SMTP.
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