9 Services
9.4.2.1.4. Server LAN Netmask
Please choose the corresponding netmask for the private IPv4
address. A netmask is a 32-bit mask used to divide an IP address into subnets and specify the
networks available hosts.
Figure 73: SimpleVPN - Server LAN Netmask
The following table shows common netmasks
Class
Netmask length # of networks # of hosts
Netmask
Class A
8
126
16,777,214
255.0.0.0
Class B
16
16,382
65,534
255.255.0.0
Class C
24
2,097,150
254
255.255.255.0
Table 14: Common netmasks
9.4.2.1.5. Transport Protocol
It is possible to change the transport protocol. By default the
transport protocol UDP is selected.
Figure 74: SimpleVPN - Transport Protocol
TCP is a connection oriented stream over an IP network. It guarantees that all sent packets will
reach the destination in the correct order. This imply the use of acknowledgement packets sent back
to the sender, and automatic retransmission, causing additional delays and a general less ecient
transmission than UDP. UDP is a connection-less protocol. Communication is datagram oriented.
The integrity is guaranteed only on the single datagram. Datagrams reach destination and can
arrive out of order or don't arrive at all. It is more ecient than TCP because it does not use
ACKs. It's generally used for real time communication, where a little percentage of packet loss rate
is preferable to the overhead of a TCP connection.
Juli 2016
VPNRouter Software Manual
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