Tc

Author: msune

tutorials/net/mtu/common.sh

@@ -56,16 +56,29 @@ destroy_link() {
 # $1 ns
 # $2 dev
 # $3 addr
-addr_add(){
+add_addr(){
 	${SUDO} ip netns exec ${1} ip addr add ${3} dev ${2}
 }
 
 # $1 ns
 # $2 route
-route_add(){
+add_route(){
 	${SUDO} ip netns exec ${1} ip route add ${2}
 }
 
+# $1 ns
+# $2 dev
+# $3 mtu
+set_iface_mtu(){
+	${SUDO} ip netns exec ${1} ip link set dev ${2} mtu ${3}
+}
+
+# $1 ns
+# $2 ip_forward value (0, 1)
+set_sysctl_ip_forward(){
+	${SUDO} ip netns exec ${1} sysctl -q -w net.ipv4.ip_forward=${2}
+}
+
 list_scenarios(){
 	find . -maxdepth 1 -type d ! -name '.*' -printf '%P\n'
 }

tutorials/net/mtu/docker/Dockerfile

@@ -14,6 +14,7 @@ RUN apt update && apt install -y --no-install-recommends \
 	iproute2       \
 	iputils-ping   \
 	make           \
+	procps         \
 	python3-scapy  \
 	tcpdump        \
     && rm -rf /var/lib/apt/lists/*

tutorials/net/mtu/scenario1/setup.sh

@@ -14,16 +14,23 @@ create_link host1 eth0 routerx ens1
 create_link routerx ens2 routery ens1
 create_link routery ens2 host2 eth0
 
-addr_add host1 eth0 192.168.0.2/24
-route_add host1 "default via 192.168.0.1"
+add_addr host1 eth0 192.168.0.2/24
+add_route host1 "default via 192.168.0.1"
 
-addr_add routerx ens1 192.168.0.1/24
-addr_add routerx ens2 192.168.1.1/24
-route_add routerx "192.168.2.0/24 via 192.168.1.2"
+add_addr routerx ens1 192.168.0.1/24
+add_addr routerx ens2 192.168.1.1/24
+add_route routerx "192.168.2.0/24 via 192.168.1.2"
 
-addr_add routery ens1 192.168.1.2/24
-addr_add routery ens2 192.168.2.1/24
-route_add routery "192.168.0.0/24 via 192.168.1.1"
+add_addr routery ens1 192.168.1.2/24
+add_addr routery ens2 192.168.2.1/24
+add_route routery "192.168.0.0/24 via 192.168.1.1"
 
-addr_add host2 eth0 192.168.2.2/24
-route_add host2 "default via 192.168.2.1"
+add_addr host2 eth0 192.168.2.2/24
+add_route host2 "default via 192.168.2.1"
+
+# routerx.ens2-routery.ens1 has a constrained MTU of 1400 (matching MTUs)
+set_iface_mtu routerx ens2 1400
+set_iface_mtu routery ens1 1400
+
+set_sysctl_ip_forward routerx 1
+set_sysctl_ip_forward routery 1