User's Manual Part 1

User’s Guide Chapter 7 – Reference Manual
GRE Interface Netmask – enter the netmask of GRE interface [dots and digits].
GRE interface IP/Netmask settings is important when configuring the GRE server.
GRE Route – this is the destination network for the GRE tunnel in the combined node/subnet format
[IP address/N].
The /N stands for the number of bits that are in the network address. There are 32 bits, so we have
32-N bits left that are part of our network. The first N bits of x.x.x.x correspond to x.0.0.0 when N=8,
our network address, and the netmask is 255.0.0.0 (when N=8).
bits netmask
/32
255.255.255.255
/31 255.255.255.252
/30 255.255.255.248
… …
/26 255.255.255.192
/25 255.255.255.128
/24 255.255.255.0
… …
/16 255.255.0.0
… …
/8 255.0.0.0
… …
/0 0.0.0.0
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