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| -rw-r--r-- | Documentation/networking/ipvlan.txt | 107 |
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diff --git a/Documentation/networking/ipvlan.txt b/Documentation/networking/ipvlan.txt new file mode 100644 index 00000000000..cf996394e46 --- /dev/null +++ b/Documentation/networking/ipvlan.txt @@ -0,0 +1,107 @@ + + IPVLAN Driver HOWTO + +Initial Release: + Mahesh Bandewar <maheshb AT google.com> + +1. Introduction: + This is conceptually very similar to the macvlan driver with one major +exception of using L3 for mux-ing /demux-ing among slaves. This property makes +the master device share the L2 with it's slave devices. I have developed this +driver in conjuntion with network namespaces and not sure if there is use case +outside of it. + + +2. Building and Installation: + In order to build the driver, please select the config item CONFIG_IPVLAN. +The driver can be built into the kernel (CONFIG_IPVLAN=y) or as a module +(CONFIG_IPVLAN=m). + + +3. Configuration: + There are no module parameters for this driver and it can be configured +using IProute2/ip utility. + + ip link add link <master-dev> <slave-dev> type ipvlan mode { l2 | L3 } + + e.g. ip link add link ipvl0 eth0 type ipvlan mode l2 + + +4. Operating modes: + IPvlan has two modes of operation - L2 and L3. For a given master device, +you can select one of these two modes and all slaves on that master will +operate in the same (selected) mode. The RX mode is almost identical except +that in L3 mode the slaves wont receive any multicast / broadcast traffic. +L3 mode is more restrictive since routing is controlled from the other (mostly) +default namespace. + +4.1 L2 mode: + In this mode TX processing happens on the stack instance attached to the +slave device and packets are switched and queued to the master device to send +out. In this mode the slaves will RX/TX multicast and broadcast (if applicable) +as well. + +4.2 L3 mode: + In this mode TX processing upto L3 happens on the stack instance attached +to the slave device and packets are switched to the stack instance of the +master device for the L2 processing and routing from that instance will be +used before packets are queued on the outbound device. In this mode the slaves +will not receive nor can send multicast / broadcast traffic. + + +5. What to choose (macvlan vs. ipvlan)? + These two devices are very similar in many regards and the specific use +case could very well define which device to choose. if one of the following +situations defines your use case then you can choose to use ipvlan - + (a) The Linux host that is connected to the external switch / router has +policy configured that allows only one mac per port. + (b) No of virtual devices created on a master exceed the mac capacity and +puts the NIC in promiscous mode and degraded performance is a concern. + (c) If the slave device is to be put into the hostile / untrusted network +namespace where L2 on the slave could be changed / misused. + + +6. Example configuration: + + +=============================================================+ + | Host: host1 | + | | + | +----------------------+ +----------------------+ | + | | NS:ns0 | | NS:ns1 | | + | | | | | | + | | | | | | + | | ipvl0 | | ipvl1 | | + | +----------#-----------+ +-----------#----------+ | + | # # | + | ################################ | + | # eth0 | + +==============================#==============================+ + + + (a) Create two network namespaces - ns0, ns1 + ip netns add ns0 + ip netns add ns1 + + (b) Create two ipvlan slaves on eth0 (master device) + ip link add link eth0 ipvl0 type ipvlan mode l2 + ip link add link eth0 ipvl1 type ipvlan mode l2 + + (c) Assign slaves to the respective network namespaces + ip link set dev ipvl0 netns ns0 + ip link set dev ipvl1 netns ns1 + + (d) Now switch to the namespace (ns0 or ns1) to configure the slave devices + - For ns0 + (1) ip netns exec ns0 bash + (2) ip link set dev ipvl0 up + (3) ip link set dev lo up + (4) ip -4 addr add 127.0.0.1 dev lo + (5) ip -4 addr add $IPADDR dev ipvl0 + (6) ip -4 route add default via $ROUTER dev ipvl0 + - For ns1 + (1) ip netns exec ns1 bash + (2) ip link set dev ipvl1 up + (3) ip link set dev lo up + (4) ip -4 addr add 127.0.0.1 dev lo + (5) ip -4 addr add $IPADDR dev ipvl1 + (6) ip -4 route add default via $ROUTER dev ipvl1 |