[mirror_ubuntu-bionic-kernel.git] / Documentation / networking / ipvlan.txt


                            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 conjunction 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> name <slave> type ipvlan [ mode MODE ] [ FLAGS ]
       where
         MODE: l3 (default) | l3s | l2
         FLAGS: bridge (default) | private | vepa

    e.g.
    (a) Following will create IPvlan link with eth0 as master in
        L3 bridge mode
          bash# ip link add link eth0 name ipvl0 type ipvlan
    (b) This command will create IPvlan link in L2 bridge mode.
          bash# ip link add link eth0 name ipvl0 type ipvlan mode l2 bridge
    (c) This command will create an IPvlan device in L2 private mode.
          bash# ip link add link eth0 name ipvlan type ipvlan mode l2 private
    (d) This command will create an IPvlan device in L2 vepa mode.
          bash# ip link add link eth0 name ipvlan type ipvlan mode l2 vepa


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 up to 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.

4.3 L3S mode:
	This is very similar to the L3 mode except that iptables (conn-tracking)
works in this mode and hence it is L3-symmetric (L3s). This will have slightly less
performance but that shouldn't matter since you are choosing this mode over plain-L3
mode to make conn-tracking work.

5. Mode flags:
	At this time following mode flags are available

5.1 bridge:
	This is the default option. To configure the IPvlan port in this mode,
user can choose to either add this option on the command-line or don't specify
anything. This is the traditional mode where slaves can cross-talk among
themseleves apart from talking through the master device.

5.2 private:
	If this option is added to the command-line, the port is set in private
mode. i.e. port wont allow cross communication between slaves.

5.3 vepa:
	If this is added to the command-line, the port is set in VEPA mode.
i.e. port will offload switching functionality to the external entity as
described in 802.1Qbg
Note: VEPA mode in IPvlan has limitations. IPvlan uses the mac-address of the
master-device, so the packets which are emitted in this mode for the adjacent
neighbor will have source and destination mac same. This will make the switch /
router send the redirect message.

6. 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 promiscuous 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
Commit	Line	Data
2ad7bf36 MB	1
	2	IPVLAN Driver HOWTO
	3
	4	Initial Release:
	5	Mahesh Bandewar <maheshb AT google.com>
	6
	7	1. Introduction:
	8	This is conceptually very similar to the macvlan driver with one major
	9	exception of using L3 for mux-ing /demux-ing among slaves. This property makes
	10	the master device share the L2 with it's slave devices. I have developed this
edb9a1b8	11	driver in conjunction with network namespaces and not sure if there is use case
2ad7bf36 MB	12	outside of it.
	13
	14
	15	2. Building and Installation:
	16	In order to build the driver, please select the config item CONFIG_IPVLAN.
	17	The driver can be built into the kernel (CONFIG_IPVLAN=y) or as a module
	18	(CONFIG_IPVLAN=m).
	19
	20
	21	3. Configuration:
	22	There are no module parameters for this driver and it can be configured
	23	using IProute2/ip utility.
	24
a190d04d MB	25	ip link add link <master> name <slave> type ipvlan [ mode MODE ] [ FLAGS ]
	26	where
	27	MODE: l3 (default) \| l3s \| l2
fe89aa6b	28	FLAGS: bridge (default) \| private \| vepa
2ad7bf36	29
a190d04d MB	30	e.g.
	31	(a) Following will create IPvlan link with eth0 as master in
	32	L3 bridge mode
	33	bash# ip link add link eth0 name ipvl0 type ipvlan
	34	(b) This command will create IPvlan link in L2 bridge mode.
	35	bash# ip link add link eth0 name ipvl0 type ipvlan mode l2 bridge
	36	(c) This command will create an IPvlan device in L2 private mode.
	37	bash# ip link add link eth0 name ipvlan type ipvlan mode l2 private
fe89aa6b MB	38	(d) This command will create an IPvlan device in L2 vepa mode.
fe89aa6b MB	39	bash# ip link add link eth0 name ipvlan type ipvlan mode l2 vepa
2ad7bf36 MB	40
	41
	42	4. Operating modes:
	43	IPvlan has two modes of operation - L2 and L3. For a given master device,
	44	you can select one of these two modes and all slaves on that master will
	45	operate in the same (selected) mode. The RX mode is almost identical except
	46	that in L3 mode the slaves wont receive any multicast / broadcast traffic.
	47	L3 mode is more restrictive since routing is controlled from the other (mostly)
	48	default namespace.
	49
	50	4.1 L2 mode:
	51	In this mode TX processing happens on the stack instance attached to the
	52	slave device and packets are switched and queued to the master device to send
	53	out. In this mode the slaves will RX/TX multicast and broadcast (if applicable)
	54	as well.
	55
	56	4.2 L3 mode:
edb9a1b8	57	In this mode TX processing up to L3 happens on the stack instance attached
2ad7bf36 MB	58	to the slave device and packets are switched to the stack instance of the
	59	master device for the L2 processing and routing from that instance will be
	60	used before packets are queued on the outbound device. In this mode the slaves
	61	will not receive nor can send multicast / broadcast traffic.
	62
4fbae7d8 MB	63	4.3 L3S mode:
	64	This is very similar to the L3 mode except that iptables (conn-tracking)
	65	works in this mode and hence it is L3-symmetric (L3s). This will have slightly less
	66	performance but that shouldn't matter since you are choosing this mode over plain-L3
	67	mode to make conn-tracking work.
2ad7bf36	68
a190d04d MB	69	5. Mode flags:
	70	At this time following mode flags are available
	71
	72	5.1 bridge:
	73	This is the default option. To configure the IPvlan port in this mode,
	74	user can choose to either add this option on the command-line or don't specify
	75	anything. This is the traditional mode where slaves can cross-talk among
	76	themseleves apart from talking through the master device.
	77
	78	5.2 private:
	79	If this option is added to the command-line, the port is set in private
	80	mode. i.e. port wont allow cross communication between slaves.
	81
fe89aa6b MB	82	5.3 vepa:
	83	If this is added to the command-line, the port is set in VEPA mode.
	84	i.e. port will offload switching functionality to the external entity as
	85	described in 802.1Qbg
	86	Note: VEPA mode in IPvlan has limitations. IPvlan uses the mac-address of the
	87	master-device, so the packets which are emitted in this mode for the adjacent
	88	neighbor will have source and destination mac same. This will make the switch /
	89	router send the redirect message.
a190d04d MB	90
a190d04d MB	91	6. What to choose (macvlan vs. ipvlan)?
2ad7bf36 MB	92	These two devices are very similar in many regards and the specific use
	93	case could very well define which device to choose. if one of the following
	94	situations defines your use case then you can choose to use ipvlan -
	95	(a) The Linux host that is connected to the external switch / router has
	96	policy configured that allows only one mac per port.
	97	(b) No of virtual devices created on a master exceed the mac capacity and
edb9a1b8	98	puts the NIC in promiscuous mode and degraded performance is a concern.
2ad7bf36 MB	99	(c) If the slave device is to be put into the hostile / untrusted network
	100	namespace where L2 on the slave could be changed / misused.
	101
	102
	103	6. Example configuration:
	104
	105	+=============================================================+
	106	\| Host: host1 \|
	107	\| \|
	108	\| +----------------------+ +----------------------+ \|
	109	\| \| NS:ns0 \| \| NS:ns1 \| \|
	110	\| \| \| \| \| \|
	111	\| \| \| \| \| \|
	112	\| \| ipvl0 \| \| ipvl1 \| \|
	113	\| +----------#-----------+ +-----------#----------+ \|
	114	\| # # \|
	115	\| ################################ \|
	116	\| # eth0 \|
	117	+==============================#==============================+
	118
	119
	120	(a) Create two network namespaces - ns0, ns1
	121	ip netns add ns0
	122	ip netns add ns1
	123
	124	(b) Create two ipvlan slaves on eth0 (master device)
	125	ip link add link eth0 ipvl0 type ipvlan mode l2
	126	ip link add link eth0 ipvl1 type ipvlan mode l2
	127
	128	(c) Assign slaves to the respective network namespaces
	129	ip link set dev ipvl0 netns ns0
	130	ip link set dev ipvl1 netns ns1
	131
	132	(d) Now switch to the namespace (ns0 or ns1) to configure the slave devices
	133	- For ns0
	134	(1) ip netns exec ns0 bash
	135	(2) ip link set dev ipvl0 up
	136	(3) ip link set dev lo up
	137	(4) ip -4 addr add 127.0.0.1 dev lo
	138	(5) ip -4 addr add $IPADDR dev ipvl0
	139	(6) ip -4 route add default via $ROUTER dev ipvl0
	140	- For ns1
	141	(1) ip netns exec ns1 bash
	142	(2) ip link set dev ipvl1 up
	143	(3) ip link set dev lo up
	144	(4) ip -4 addr add 127.0.0.1 dev lo
	145	(5) ip -4 addr add $IPADDR dev ipvl1
	146	(6) ip -4 route add default via $ROUTER dev ipvl1