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Commit 6e076537 authored by David Ahern's avatar David Ahern Committed by David S. Miller
Browse files

net: vrf: Documentation update 



Update vrf documentation for changes made to 4.4 - 4.8 kernels
and iproute2 support for vrf keyword.

Signed-off-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b38a75d2

Documentation/networking/vrf.txt

+103 −98
Original line number Diff line number Diff line
@@ -15,9 +15,9 @@ the use of higher priority ip rules (Policy Based Routing, PBR) to take 
precedence over the VRF device rules directing specific traffic as desired.



In addition, VRF devices allow VRFs to be nested within namespaces. For

example network namespaces provide separation of network interfaces at L1

(Layer 1 separation), VLANs on the interfaces within a namespace provide

L2 separation and then VRF devices provide L3 separation.

example network namespaces provide separation of network interfaces at the

device layer, VLANs on the interfaces within a namespace provide L2 separation

and then VRF devices provide L3 separation.



Design

------
@@ -37,21 +37,22 @@ are then enslaved to a VRF device: 
                              +------+ +------+



Packets received on an enslaved device and are switched to the VRF device

using an rx_handler which gives the impression that packets flow through

the VRF device. Similarly on egress routing rules are used to send packets

to the VRF device driver before getting sent out the actual interface. This

allows tcpdump on a VRF device to capture all packets into and out of the

VRF as a whole.[1] Similarly, netfilter [2] and tc rules can be applied

using the VRF device to specify rules that apply to the VRF domain as a whole.

in the IPv4 and IPv6 processing stacks giving the impression that packets

flow through the VRF device. Similarly on egress routing rules are used to

send packets to the VRF device driver before getting sent out the actual

interface. This allows tcpdump on a VRF device to capture all packets into

and out of the VRF as a whole.[1] Similarly, netfilter[2] and tc rules can be

applied using the VRF device to specify rules that apply to the VRF domain

as a whole.



[1] Packets in the forwarded state do not flow through the device, so those

    packets are not seen by tcpdump. Will revisit this limitation in a

    future release.



[2] Iptables on ingress is limited to NF_INET_PRE_ROUTING only with skb->dev

    set to real ingress device and egress is limited to NF_INET_POST_ROUTING.

    Will revisit this limitation in a future release.



[2] Iptables on ingress supports PREROUTING with skb->dev set to the real

    ingress device and both INPUT and PREROUTING rules with skb->dev set to

    the VRF device. For egress POSTROUTING and OUTPUT rules can be written

    using either the VRF device or real egress device.



Setup

-----
@@ -59,23 +60,33 @@ Setup 
   e.g, ip link add vrf-blue type vrf table 10

        ip link set dev vrf-blue up



2. Rules are added that send lookups to the associated FIB table when the

   iif or oif is the VRF device. e.g.,

2. An l3mdev FIB rule directs lookups to the table associated with the device.

   A single l3mdev rule is sufficient for all VRFs. The VRF device adds the

   l3mdev rule for IPv4 and IPv6 when the first device is created with a

   default preference of 1000. Users may delete the rule if desired and add

   with a different priority or install per-VRF rules.



   Prior to the v4.8 kernel iif and oif rules are needed for each VRF device:

       ip ru add oif vrf-blue table 10

       ip ru add iif vrf-blue table 10



   Set the default route for the table (and hence default route for the VRF).

   e.g, ip route add table 10 prohibit default

3. Set the default route for the table (and hence default route for the VRF).

       ip route add table 10 unreachable default



3. Enslave L3 interfaces to a VRF device.

   e.g,  ip link set dev eth1 master vrf-blue

4. Enslave L3 interfaces to a VRF device.

       ip link set dev eth1 master vrf-blue



   Local and connected routes for enslaved devices are automatically moved to

   the table associated with VRF device. Any additional routes depending on

   the enslaved device will need to be reinserted following the enslavement.

   the enslaved device are dropped and will need to be reinserted to the VRF

   FIB table following the enslavement.



   The IPv6 sysctl option keep_addr_on_down can be enabled to keep IPv6 global

   addresses as VRF enslavement changes.

       sysctl -w net.ipv6.conf.all.keep_addr_on_down=1



4. Additional VRF routes are added to associated table.

   e.g., ip route add table 10 ...

5. Additional VRF routes are added to associated table.

       ip route add table 10 ...





Applications
@@ -87,39 +98,34 @@ VRF device: 


or to specify the output device using cmsg and IP_PKTINFO.



TCP services running in the default VRF context (ie., not bound to any VRF

device) can work across all VRF domains by enabling the tcp_l3mdev_accept

sysctl option:

    sysctl -w net.ipv4.tcp_l3mdev_accept=1



Limitations

-----------

Index of original ingress interface is not available via cmsg. Will address

soon.

netfilter rules on the VRF device can be used to limit access to services

running in the default VRF context as well.



The default VRF does not have limited scope with respect to port bindings.

That is, if a process does a wildcard bind to a port in the default VRF it

owns the port across all VRF domains within the network namespace.



################################################################################



Using iproute2 for VRFs

=======================

VRF devices do *not* have to start with 'vrf-'. That is a convention used here

for emphasis of the device type, similar to use of 'br' in bridge names.

iproute2 supports the vrf keyword as of v4.7. For backwards compatibility this

section lists both commands where appropriate -- with the vrf keyword and the

older form without it.



1. Create a VRF



   To instantiate a VRF device and associate it with a table:

       $ ip link add dev NAME type vrf table ID



   Remember to add the ip rules as well:

       $ ip ru add oif NAME table 10

       $ ip ru add iif NAME table 10

       $ ip -6 ru add oif NAME table 10

       $ ip -6 ru add iif NAME table 10



   Without the rules route lookups are not directed to the table.



   For example:

   $ ip link add dev vrf-blue type vrf table 10

   $ ip ru add pref 200 oif vrf-blue table 10

   $ ip ru add pref 200 iif vrf-blue table 10

   $ ip -6 ru add pref 200 oif vrf-blue table 10

   $ ip -6 ru add pref 200 iif vrf-blue table 10



   As of v4.8 the kernel supports the l3mdev FIB rule where a single rule

   covers all VRFs. The l3mdev rule is created for IPv4 and IPv6 on first

   device create.



2. List VRFs
@@ -129,16 +135,16 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 


   For example:

   $ ip -d link show type vrf

   11: vrf-mgmt: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000

   11: mgmt: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000

       link/ether 72:b3:ba:91:e2:24 brd ff:ff:ff:ff:ff:ff promiscuity 0

       vrf table 1 addrgenmode eui64

   12: vrf-red: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000

   12: red: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000

       link/ether b6:6f:6e:f6:da:73 brd ff:ff:ff:ff:ff:ff promiscuity 0

       vrf table 10 addrgenmode eui64

   13: vrf-blue: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000

   13: blue: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000

       link/ether 36:62:e8:7d:bb:8c brd ff:ff:ff:ff:ff:ff promiscuity 0

       vrf table 66 addrgenmode eui64

   14: vrf-green: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000

   14: green: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000

       link/ether e6:28:b8:63:70:bb brd ff:ff:ff:ff:ff:ff promiscuity 0

       vrf table 81 addrgenmode eui64
@@ -146,43 +152,44 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 
   Or in brief output:



   $ ip -br link show type vrf

   vrf-mgmt         UP             72:b3:ba:91:e2:24 <NOARP,MASTER,UP,LOWER_UP>

   vrf-red          UP             b6:6f:6e:f6:da:73 <NOARP,MASTER,UP,LOWER_UP>

   vrf-blue         UP             36:62:e8:7d:bb:8c <NOARP,MASTER,UP,LOWER_UP>

   vrf-green        UP             e6:28:b8:63:70:bb <NOARP,MASTER,UP,LOWER_UP>

   mgmt         UP             72:b3:ba:91:e2:24 <NOARP,MASTER,UP,LOWER_UP>

   red          UP             b6:6f:6e:f6:da:73 <NOARP,MASTER,UP,LOWER_UP>

   blue         UP             36:62:e8:7d:bb:8c <NOARP,MASTER,UP,LOWER_UP>

   green        UP             e6:28:b8:63:70:bb <NOARP,MASTER,UP,LOWER_UP>





3. Assign a Network Interface to a VRF



   Network interfaces are assigned to a VRF by enslaving the netdevice to a

   VRF device:

       $ ip link set dev NAME master VRF-NAME

       $ ip link set dev NAME master NAME



   On enslavement connected and local routes are automatically moved to the

   table associated with the VRF device.



   For example:

   $ ip link set dev eth0 master vrf-mgmt

   $ ip link set dev eth0 master mgmt





4. Show Devices Assigned to a VRF



   To show devices that have been assigned to a specific VRF add the master

   option to the ip command:

       $ ip link show master VRF-NAME

       $ ip link show vrf NAME

       $ ip link show master NAME



   For example:

   $ ip link show master vrf-red

   3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vrf-red state UP mode DEFAULT group default qlen 1000

   $ ip link show vrf red

   3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master red state UP mode DEFAULT group default qlen 1000

       link/ether 02:00:00:00:02:02 brd ff:ff:ff:ff:ff:ff

   4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vrf-red state UP mode DEFAULT group default qlen 1000

   4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master red state UP mode DEFAULT group default qlen 1000

       link/ether 02:00:00:00:02:03 brd ff:ff:ff:ff:ff:ff

   7: eth5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master vrf-red state DOWN mode DEFAULT group default qlen 1000

   7: eth5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master red state DOWN mode DEFAULT group default qlen 1000

       link/ether 02:00:00:00:02:06 brd ff:ff:ff:ff:ff:ff





   Or using the brief output:

   $ ip -br link show master vrf-red

   $ ip -br link show master red

   eth1             UP             02:00:00:00:02:02 <BROADCAST,MULTICAST,UP,LOWER_UP>

   eth2             UP             02:00:00:00:02:03 <BROADCAST,MULTICAST,UP,LOWER_UP>

   eth5             DOWN           02:00:00:00:02:06 <BROADCAST,MULTICAST>
@@ -192,14 +199,15 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 


   To list neighbor entries associated with devices enslaved to a VRF device

   add the master option to the ip command:

       $ ip [-6] neigh show master VRF-NAME

       $ ip [-6] neigh show vrf NAME

       $ ip [-6] neigh show master NAME



   For example:

   $  ip neigh show master vrf-red

   $  ip neigh show vrf red

   10.2.1.254 dev eth1 lladdr a6:d9:c7:4f:06:23 REACHABLE

   10.2.2.254 dev eth2 lladdr 5e:54:01:6a:ee:80 REACHABLE



    $ ip -6 neigh show master vrf-red

    $ ip -6 neigh show vrf red

    2002:1::64 dev eth1 lladdr a6:d9:c7:4f:06:23 REACHABLE
@@ -207,11 +215,12 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 


   To show addresses for interfaces associated with a VRF add the master

   option to the ip command:

       $ ip addr show master VRF-NAME

       $ ip addr show vrf NAME

       $ ip addr show master NAME



   For example:

   $ ip addr show master vrf-red

   3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vrf-red state UP group default qlen 1000

   $ ip addr show vrf red

   3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master red state UP group default qlen 1000

       link/ether 02:00:00:00:02:02 brd ff:ff:ff:ff:ff:ff

       inet 10.2.1.2/24 brd 10.2.1.255 scope global eth1

          valid_lft forever preferred_lft forever
@@ -219,7 +228,7 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 
          valid_lft forever preferred_lft forever

       inet6 fe80::ff:fe00:202/64 scope link

          valid_lft forever preferred_lft forever

   4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vrf-red state UP group default qlen 1000

   4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master red state UP group default qlen 1000

       link/ether 02:00:00:00:02:03 brd ff:ff:ff:ff:ff:ff

       inet 10.2.2.2/24 brd 10.2.2.255 scope global eth2

          valid_lft forever preferred_lft forever
@@ -227,11 +236,11 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 
          valid_lft forever preferred_lft forever

       inet6 fe80::ff:fe00:203/64 scope link

          valid_lft forever preferred_lft forever

   7: eth5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master vrf-red state DOWN group default qlen 1000

   7: eth5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master red state DOWN group default qlen 1000

       link/ether 02:00:00:00:02:06 brd ff:ff:ff:ff:ff:ff



   Or in brief format:

   $ ip -br addr show master vrf-red

   $ ip -br addr show vrf red

   eth1             UP             10.2.1.2/24 2002:1::2/120 fe80::ff:fe00:202/64

   eth2             UP             10.2.2.2/24 2002:2::2/120 fe80::ff:fe00:203/64

   eth5             DOWN
@@ -241,10 +250,11 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 


   To show routes for a VRF use the ip command to display the table associated

   with the VRF device:

       $ ip [-6] route show vrf NAME

       $ ip [-6] route show table ID



   For example:

   $ ip route show table vrf-red

   $ ip route show vrf red

   prohibit default

   broadcast 10.2.1.0 dev eth1  proto kernel  scope link  src 10.2.1.2

   10.2.1.0/24 dev eth1  proto kernel  scope link  src 10.2.1.2
@@ -255,7 +265,7 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 
   local 10.2.2.2 dev eth2  proto kernel  scope host  src 10.2.2.2

   broadcast 10.2.2.255 dev eth2  proto kernel  scope link  src 10.2.2.2



   $ ip -6 route show table vrf-red

   $ ip -6 route show vrf red

   local 2002:1:: dev lo  proto none  metric 0  pref medium

   local 2002:1::2 dev lo  proto none  metric 0  pref medium

   2002:1::/120 dev eth1  proto kernel  metric 256  pref medium
@@ -268,23 +278,24 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 
   local fe80::ff:fe00:203 dev lo  proto none  metric 0  pref medium

   fe80::/64 dev eth1  proto kernel  metric 256  pref medium

   fe80::/64 dev eth2  proto kernel  metric 256  pref medium

   ff00::/8 dev vrf-red  metric 256  pref medium

   ff00::/8 dev red  metric 256  pref medium

   ff00::/8 dev eth1  metric 256  pref medium

   ff00::/8 dev eth2  metric 256  pref medium





8. Route Lookup for a VRF



   A test route lookup can be done for a VRF by adding the oif option to ip:

       $ ip [-6] route get oif VRF-NAME ADDRESS

   A test route lookup can be done for a VRF:

       $ ip [-6] route get vrf NAME ADDRESS

       $ ip [-6] route get oif NAME ADDRESS



   For example:

   $ ip route get 10.2.1.40 oif vrf-red

   10.2.1.40 dev eth1  table vrf-red  src 10.2.1.2

   $ ip route get 10.2.1.40 vrf red

   10.2.1.40 dev eth1  table red  src 10.2.1.2

       cache



   $ ip -6 route get 2002:1::32 oif vrf-red

   2002:1::32 from :: dev eth1  table vrf-red  proto kernel  src 2002:1::2  metric 256  pref medium

   $ ip -6 route get 2002:1::32 vrf red

   2002:1::32 from :: dev eth1  table red  proto kernel  src 2002:1::2  metric 256  pref medium





9. Removing Network Interface from a VRF
@@ -303,46 +314,40 @@ for emphasis of the device type, similar to use of 'br' in bridge names. 


Commands used in this example:



cat >> /etc/iproute2/rt_tables <<EOF

1  vrf-mgmt

10 vrf-red

66 vrf-blue

81 vrf-green

cat >> /etc/iproute2/rt_tables.d/vrf.conf <<EOF

1  mgmt

10 red

66 blue

81 green

EOF



function vrf_create

{

    VRF=$1

    TBID=$2

    # create VRF device

    ip link add vrf-${VRF} type vrf table ${TBID}



    # add rules that direct lookups to vrf table

    ip ru add pref 200 oif vrf-${VRF} table ${TBID}

    ip ru add pref 200 iif vrf-${VRF} table ${TBID}

    ip -6 ru add pref 200 oif vrf-${VRF} table ${TBID}

    ip -6 ru add pref 200 iif vrf-${VRF} table ${TBID}

    # create VRF device

    ip link add ${VRF} type vrf table ${TBID}



    if [ "${VRF}" != "mgmt" ]; then

        ip route add table ${TBID} prohibit default

        ip route add table ${TBID} unreachable default

    fi

    ip link set dev vrf-${VRF} up

    ip link set dev vrf-${VRF} state up

    ip link set dev ${VRF} up

}



vrf_create mgmt 1

ip link set dev eth0 master vrf-mgmt

ip link set dev eth0 master mgmt



vrf_create red 10

ip link set dev eth1 master vrf-red

ip link set dev eth2 master vrf-red

ip link set dev eth5 master vrf-red

ip link set dev eth1 master red

ip link set dev eth2 master red

ip link set dev eth5 master red



vrf_create blue 66

ip link set dev eth3 master vrf-blue

ip link set dev eth3 master blue



vrf_create green 81

ip link set dev eth4 master vrf-green

ip link set dev eth4 master green





Interface addresses from /etc/network/interfaces: