1 2 IPVLAN Driver HOWTO 3 4Initial Release: 5 Mahesh Bandewar <maheshb AT google.com> 6 71. Introduction: 8 This is conceptually very similar to the macvlan driver with one major 9exception of using L3 for mux-ing /demux-ing among slaves. This property makes 10the master device share the L2 with it's slave devices. I have developed this 11driver in conjunction with network namespaces and not sure if there is use case 12outside of it. 13 14 152. Building and Installation: 16 In order to build the driver, please select the config item CONFIG_IPVLAN. 17The driver can be built into the kernel (CONFIG_IPVLAN=y) or as a module 18(CONFIG_IPVLAN=m). 19 20 213. Configuration: 22 There are no module parameters for this driver and it can be configured 23using IProute2/ip utility. 24 25 ip link add link <master-dev> <slave-dev> type ipvlan mode { l2 | l3 | l3s } 26 27 e.g. ip link add link ipvl0 eth0 type ipvlan mode l2 28 29 304. Operating modes: 31 IPvlan has two modes of operation - L2 and L3. For a given master device, 32you can select one of these two modes and all slaves on that master will 33operate in the same (selected) mode. The RX mode is almost identical except 34that in L3 mode the slaves wont receive any multicast / broadcast traffic. 35L3 mode is more restrictive since routing is controlled from the other (mostly) 36default namespace. 37 384.1 L2 mode: 39 In this mode TX processing happens on the stack instance attached to the 40slave device and packets are switched and queued to the master device to send 41out. In this mode the slaves will RX/TX multicast and broadcast (if applicable) 42as well. 43 444.2 L3 mode: 45 In this mode TX processing up to L3 happens on the stack instance attached 46to the slave device and packets are switched to the stack instance of the 47master device for the L2 processing and routing from that instance will be 48used before packets are queued on the outbound device. In this mode the slaves 49will not receive nor can send multicast / broadcast traffic. 50 514.3 L3S mode: 52 This is very similar to the L3 mode except that iptables (conn-tracking) 53works in this mode and hence it is L3-symmetric (L3s). This will have slightly less 54performance but that shouldn't matter since you are choosing this mode over plain-L3 55mode to make conn-tracking work. 56 575. What to choose (macvlan vs. ipvlan)? 58 These two devices are very similar in many regards and the specific use 59case could very well define which device to choose. if one of the following 60situations defines your use case then you can choose to use ipvlan - 61 (a) The Linux host that is connected to the external switch / router has 62policy configured that allows only one mac per port. 63 (b) No of virtual devices created on a master exceed the mac capacity and 64puts the NIC in promiscuous mode and degraded performance is a concern. 65 (c) If the slave device is to be put into the hostile / untrusted network 66namespace where L2 on the slave could be changed / misused. 67 68 696. Example configuration: 70 71 +=============================================================+ 72 | Host: host1 | 73 | | 74 | +----------------------+ +----------------------+ | 75 | | NS:ns0 | | NS:ns1 | | 76 | | | | | | 77 | | | | | | 78 | | ipvl0 | | ipvl1 | | 79 | +----------#-----------+ +-----------#----------+ | 80 | # # | 81 | ################################ | 82 | # eth0 | 83 +==============================#==============================+ 84 85 86 (a) Create two network namespaces - ns0, ns1 87 ip netns add ns0 88 ip netns add ns1 89 90 (b) Create two ipvlan slaves on eth0 (master device) 91 ip link add link eth0 ipvl0 type ipvlan mode l2 92 ip link add link eth0 ipvl1 type ipvlan mode l2 93 94 (c) Assign slaves to the respective network namespaces 95 ip link set dev ipvl0 netns ns0 96 ip link set dev ipvl1 netns ns1 97 98 (d) Now switch to the namespace (ns0 or ns1) to configure the slave devices 99 - For ns0 100 (1) ip netns exec ns0 bash 101 (2) ip link set dev ipvl0 up 102 (3) ip link set dev lo up 103 (4) ip -4 addr add 127.0.0.1 dev lo 104 (5) ip -4 addr add $IPADDR dev ipvl0 105 (6) ip -4 route add default via $ROUTER dev ipvl0 106 - For ns1 107 (1) ip netns exec ns1 bash 108 (2) ip link set dev ipvl1 up 109 (3) ip link set dev lo up 110 (4) ip -4 addr add 127.0.0.1 dev lo 111 (5) ip -4 addr add $IPADDR dev ipvl1 112 (6) ip -4 route add default via $ROUTER dev ipvl1 113