ip netns add a
ip netns add b1
ip netns add b2
ip netns add c

ip link add a0    type dummy
ip link add a-b1  type veth peer name b1-a
ip link add a-b2  type veth peer name b2-a
ip link add b1-b2 type veth peer name b2-b1
ip link add b1-c  type veth peer name c-b1
ip link add b2-c  type veth peer name c-b2
ip link add c0    type dummy
ip link set dev a0    netns a
ip link set dev a-b1  netns a
ip link set dev a-b2  netns a
ip link set dev b1-a  netns b1
ip link set dev b1-b2 netns b1
ip link set dev b1-c  netns b1
ip link set dev b2-a  netns b2
ip link set dev b2-b1 netns b2
ip link set dev b2-c  netns b2
ip link set dev c-b1  netns c
ip link set dev c-b2  netns c
ip link set dev c0    netns c

ip netns exec a /bin/bash
export PS1="${debian_chroot:+($debian_chroot)}\u@ns-a-:\w\$ "
sysctl -w 'net.ipv6.conf.all.forwarding=1'
ip link set up dev lo
ip link set up dev a0
ip link set up dev a-b1
ip link set up dev a-b2
ip addr add fc0a::a/64 dev a0
ip addr add fc01::a/64 dev a-b1
ip addr add fc02::a/64 dev a-b2

Prüfen:

ip -6 -c addr show

ip netns exec b1 /bin/bash
export PS1="${debian_chroot:+($debian_chroot)}\u@ns-b1-:\w\$ "
sysctl -w 'net.ipv6.conf.all.forwarding=1'
ip link set up dev lo
ip link set up dev b1-a
ip link set up dev b1-b2
ip link set up dev b1-c
ip addr add fc01::b1/64 dev b1-a
ip addr add fc03::b1/64 dev b1-b2
ip addr add fc04::b1/64 dev b1-c

Prüfen:

ip -6 -c addr show
ip -6 -c route show
ping -qc1 fc01::a

ip netns exec b2 /bin/bash
export PS1="${debian_chroot:+($debian_chroot)}\u@ns-b2-:\w\$ "
sysctl -w 'net.ipv6.conf.all.forwarding=1'
ip link set up dev lo
ip link set up dev b2-a
ip link set up dev b2-b1
ip link set up dev b2-c
ip addr add fc02::b2/64 dev b2-a
ip addr add fc03::b2/64 dev b2-b1
ip addr add fc05::b2/64 dev b2-c

Prüfen:

ip -6 -c addr show
ip -6 -c route show
ping -qc1 fc02::a
ping -qc1 fc03::b1

ip netns exec c /bin/bash
export PS1="${debian_chroot:+($debian_chroot)}\u@ns-c-:\w\$ "
sysctl -w 'net.ipv6.conf.all.forwarding=1'
ip link set up dev lo
ip link set up dev c-b1
ip link set up dev c-b2
ip link set up dev c0
ip addr add fc04::c/64 dev c-b1
ip addr add fc05::c/64 dev c-b2
ip addr add fc0c::c/64 dev c0

Prüfen:

ip -6 -c addr show
ip -6 -c route show
ping -qc1 fc04::b1
ping -qc1 fc05::b2