HPE FlexNetwork HSR6800 Configuration Manual page 324

Connecting networks running different protocols over a single backbone
Figure 126 Network diagram
IPv6 network 1
Device A
IPv4 network 1
As shown in
and IPv4 network 2 are IPv4 networks. Through the GRE tunnel between Device A and Device B,
IPv6 network 1 can communicate with IPv6 network 2 and IPv4 network 1 can communicate with
IPv4 network 2, without affecting each other.
Enlarging network scope
Figure 127 Network diagram
Device A
Host A
In an IP network, the maximum TTL value of a packet is 255. If two devices have more than 255 hops
in between, they cannot communicate with each other. By using a GRE tunnel, you can hide some
hops to enlarge the network scope. As shown in
and Device D) of the GRE tunnel are counted in hop count calculation. Therefore, there are only
three hops between Host A and Host B.
Internet
GRE tunnel
Figure 126, IPv6 network 1 and IPv6 network 2 are IPv6 networks, and IPv4 network 1
GRE tunnel
IP network
Device B
IP network
IPv6 network 2
Device B
IPv4 network 2
Device D
IP network
Device C
Host B
Figure 127, only the tunnel-end devices (Device A
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