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Sets up IP subnets over a single Ethernet broadcast domain formed by a Linux bridge.
#!/usr/bin/env bash
set -euo pipefail
create_bridge() {
local nsname="$1"
local ifname="$2"
echo "Creating bridge ${nsname}/${ifname}"
ip netns add ${nsname}
ip netns exec ${nsname} ip link set lo up
ip netns exec ${nsname} ip link add ${ifname} type bridge
ip netns exec ${nsname} ip link set ${ifname} up
}
create_end_host() {
local host_nsname="$1"
local peer1_ifname="$2a"
local peer2_ifname="$2b"
local peer1_ifaddr="$3"
local bridge_nsname="$4"
local bridge_ifname="$5"
echo "Creating end host ${host_nsname} ${peer1_ifaddr} connected to ${bridge_nsname}/${bridge_ifname} bridge"
# Create end host network namespace.
ip netns add ${host_nsname}
ip netns exec ${host_nsname} ip link set lo up
# Create a veth pair connecting end host and bridge namespaces.
ip link add ${peer1_ifname} netns ${host_nsname} type veth peer \
${peer2_ifname} netns ${bridge_nsname}
ip netns exec ${host_nsname} ip link set ${peer1_ifname} up
ip netns exec ${bridge_nsname} ip link set ${peer2_ifname} up
# Setting host's IP address.
ip netns exec ${host_nsname} ip addr add ${peer1_ifaddr} dev ${peer1_ifname}
# Attach peer2 interface to the bridge.
ip netns exec ${bridge_nsname} ip link set ${peer2_ifname} master ${bridge_ifname}
}
# ---=== Scenario 1: 1:1 mapping ===---
setup__one_to_one_mapping() {
create_bridge netns_br0 br0
create_end_host netns_veth0 veth0 '192.168.0.5/24' netns_br0 br0
create_end_host netns_veth1 veth1 '192.168.0.6/24' netns_br0 br0
create_end_host netns_veth2 veth2 '192.168.0.7/24' netns_br0 br0
}
teardown__one_to_one_mapping() {
ip netns delete netns_br0
ip netns delete netns_veth0
ip netns delete netns_veth1
ip netns delete netns_veth2
}
# ---=== Scenario 2: 1:N mapping ===---
setup__one_to_many_mapping() {
create_bridge netns_br0 br0
# Subnet 1
create_end_host netns_veth0 veth0 192.168.0.5/24 netns_br0 br0
create_end_host netns_veth1 veth1 192.168.0.6/24 netns_br0 br0
create_end_host netns_veth2 veth2 192.168.0.7/24 netns_br0 br0
# Subnet 2
create_end_host netns_veth3 veth3 192.168.1.5/24 netns_br0 br0
create_end_host netns_veth4 veth4 192.168.1.6/24 netns_br0 br0
create_end_host netns_veth5 veth5 192.168.1.7/24 netns_br0 br0
}
teardown__one_to_many_mapping() {
ip netns delete netns_br0
ip netns delete netns_veth0
ip netns delete netns_veth1
ip netns delete netns_veth2
ip netns delete netns_veth3
ip netns delete netns_veth4
ip netns delete netns_veth5
}
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