VRF

VRF devices combined with ip rules provides the ability to create virtual routing and forwarding domains (aka VRFs, VRF-lite to be specific) in the Linux network stack. One use case is the multi-tenancy problem where each tenant has their own unique routing tables and in the very least need different default gateways.

Warning

VRFs are an “needs testing” feature. If you think things should be different then they are implemented and handled right now - please feedback via a task created in Phabricator.

Configuration

A VRF device is created with an associated route table. Network interfaces are then enslaved to a VRF device.

set vrf name <name>
Create new VRF instance with <name>. The name is used when placing individual interfaces into the VRF.
set vrf name <name> table <id>

Configure use routing table <id> used by VRF <name>.

Note

A routing table ID can not be modified once it is assigned. It can only be changed by deleting and re-adding the VRF instance.

set vrf bind-to-all

By default the scope of the port bindings for unbound sockets is limited to the default VRF. That is, it will not be matched by packets arriving on interfaces enslaved to a VRF and processes may bind to the same port if they bind to a VRF.

TCP & UDP services running in the default VRF context (ie., not bound to any VRF device) can work across all VRF domains by enabling this option.

Interfaces

When VRFs are used it is not only mandatory to create a VRF but also the VRF itself needs to be assigned to an interface.

set interfaces <dummy | ethernet | bonding | bridge | pppoe> <interface> vrf <name>
Assign interface identified by <interface> to VRF named <name>.

Routing

Static

Static routes are manually configured routes, which, in general, cannot be updated dynamically from information VyOS learns about the network topology from other routing protocols. However, if a link fails, the router will remove routes, including static routes, from the RIPB that used this interface to reach the next hop. In general, static routes should only be used for very simple network topologies, or to override the behavior of a dynamic routing protocol for a small number of routes. The collection of all routes the router has learned from its configuration or from its dynamic routing protocols is stored in the RIB. Unicast routes are directly used to determine the forwarding table used for unicast packet forwarding.

Static Routes
set protocols vrf <name> static route <subnet> next-hop <address>
Configure next-hop <address> for an IPv4 static route in the VRF identified by <name>. Multiple static routes can be created.
set protocols vrf <name> static route <subnet> next-hop <address> disable
Disable IPv4 static route entry in the VRF identified by <name>
set protocols vrf <name> static route <subnet> next-hop <address> distance <distance>

Defines next-hop distance for this route, routes with smaller administrative distance are elected prior those with a higher distance.

Range is 1 to 255, default is 1.

set protocols vrf <name> static route6 <subnet> next-hop <address>
Configure next-hop <address> for an IPv6 static route in the VRF identified by <name>. Multiple IPv6 static routes can be created.
set protocols vrf <name> static route6 <subnet> next-hop <address> disable
Disable IPv6 static route entry in the VRF identified by <name>.
set protocols vrf <name> static route6 <subnet> next-hop <address> distance <distance>

Defines next-hop distance for this route, routes with smaller administrative distance are elected prior those with a higher distance.

Range is 1 to 255, default is 1.

Note

Routes with a distance of 255 are effectively disabled and not installed into the kernel.

Leaking
set protocols vrf <name> static route <subnet> next-hop <address> next-hop-vrf <default | vrf-name>
Use this command if you have shared services or routes that should be shared between multiple VRF instances. This will add an IPv4 route to VRF <name> routing table to reach a <subnet> via a next-hop gatewys <address> in a different VRF or leak it into the default VRF.
set protocols vrf <name> static route6 <subnet> next-hop <address> next-hop-vrf <default | vrf-name>
Use this command if you have shared services or routes that should be shared between multiple VRF instances. This will add an IPv6 route to VRF <name> routing table to reach a <subnet> via a next-hop gatewys <address> in a different VRF or leak it into the default VRF.
Interface Routes
set protocols vrf <name> static interface-route <subnet> next-hop-interface <interface>
Allows you to configure the next-hop interface for an interface-based IPv4 static route. <interface> will be the next-hop interface where trafic is routed for the given <subnet>.
set protocols vrf <name> static interface-route <subnet> next-hop-interface <interface> disable
Disables interface-based IPv4 static route.
set protocols vrf <name> static interface-route <subnet> next-hop-interface <interface> distance <distance>

Defines next-hop distance for this route, routes with smaller administrative distance are elected prior those with a higher distance.

Range is 1 to 255, default is 1.

set protocols vrf <name> static interface-route6 <subnet> next-hop-interface <interface>
Allows you to configure the next-hop interface for an interface-based IPv6 static route. <interface> will be the next-hop interface where trafic is routed for the given <subnet>.
set protocols vrf <name> static interface-route6 <subnet> next-hop-interface <interface> disable
Disables interface-based IPv6 static route.
set protocols vrf <name> static interface-route6 <subnet> next-hop-interface <interface> distance <distance>

Defines next-hop distance for this route, routes with smaller administrative distance are elected prior those with a higher distance.

Range is 1 to 255, default is 1.

Blackhole
set protocols vrf <name> static route <subnet> blackhole
Use this command to configure a “black-hole” route on the router. A black-hole route is a route for which the system silently discard packets that are matched. This prevents networks leaking out public interfaces, but it does not prevent them from being used as a more specific route inside your network.
set protocols vrf <name> static route <subnet> blackhole distance <distance>
Defines blackhole distance for this route, routes with smaller administrative distance are elected prior those with a higher distance.
set protocols vrf <name> static route6 <subnet> blackhole
Use this command to configure a “black-hole” route on the router. A black-hole route is a route for which the system silently discard packets that are matched. This prevents networks leaking out public interfaces, but it does not prevent them from being used as a more specific route inside your network.
set protocols vrf <name> static route6 <subnet> blackhole distance <distance>
Defines blackhole distance for this route, routes with smaller administrative distance are elected prior those with a higher distance.

Operation

It is not sufficient to only configure a VRF but VRFs must be maintained, too. For VR Fmaintenance the followin operational commands are in place.

show vrf

List VRFs that have been created

[email protected]:~$ show vrf
VRF name          state     mac address        flags                     interfaces
--------          -----     -----------        -----                     ----------
blue              up        de:c4:83:d8:74:24  noarp,master,up,lower_up  dum200,eth0.302
red               up        be:36:ce:02:df:aa  noarp,master,up,lower_up  dum100,eth0.300,bond0.100,peth0

Note

Command should probably be extended to list also the real interfaces assigned to this one VRF to get a better overview.

show vrf <name>
[email protected]:~$ show vrf name blue
VRF name          state     mac address        flags                     interfaces
--------          -----     -----------        -----                     ----------
blue              up        de:c4:83:d8:74:24  noarp,master,up,lower_up  dum200,eth0.302
show ip route vrf <name>

Display IPv4 routing table for VRF identified by <name>.

[email protected]:~$ show ip route vrf blue
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       F - PBR, f - OpenFabric,
       > - selected route, * - FIB route, q - queued route, r - rejected route

VRF blue:
K   0.0.0.0/0 [255/8192] unreachable (ICMP unreachable), 00:00:50
S>* 172.16.0.0/16 [1/0] via 192.0.2.1, dum1, 00:00:02
C>* 192.0.2.0/24 is directly connected, dum1, 00:00:06
show ipv6 route vrf <name>

Display IPv6 routing table for VRF identified by <name>.

[email protected]:~$ show ipv6 route vrf red
Codes: K - kernel route, C - connected, S - static, R - RIPng,
       O - OSPFv3, I - IS-IS, B - BGP, N - NHRP, T - Table,
       v - VNC, V - VNC-Direct, A - Babel, D - SHARP, F - PBR,
       f - OpenFabric,
       > - selected route, * - FIB route, q - queued route, r - rejected route

VRF red:
K   ::/0 [255/8192] unreachable (ICMP unreachable), 00:43:20
C>* 2001:db8::/64 is directly connected, dum1, 00:02:19
C>* fe80::/64 is directly connected, dum1, 00:43:19
K>* ff00::/8 [0/256] is directly connected, dum1, 00:43:19
ping <host> vrf <name>

The ping command is used to test whether a network host is reachable or not.

Ping uses ICMP protocol’s mandatory ECHO_REQUEST datagram to elicit an ICMP ECHO_RESPONSE from a host or gateway. ECHO_REQUEST datagrams (pings) will have an IP and ICMP header, followed by “struct timeval” and an arbitrary number of pad bytes used to fill out the packet.

When doing fault isolation with ping, your should first run it on the local host, to verify that the local network interface is up and running. Then, continue with hosts and gateways further down the road towards your destination. Round-trip times and packet loss statistics are computed.

Duplicate packets are not included in the packet loss calculation, although the round-trip time of these packets is used in calculating the minimum/ average/maximum round-trip time numbers.

Ping command can be interrupted at any given time using <Ctrl>+c- A brief statistic is shown afterwards.

[email protected]:~$ ping 192.0.2.1 vrf red
PING 192.0.2.1 (192.0.2.1) 56(84) bytes of data.
64 bytes from 192.0.2.1: icmp_seq=1 ttl=64 time=0.070 ms
64 bytes from 192.0.2.1: icmp_seq=2 ttl=64 time=0.078 ms
^C
--- 192.0.2.1 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 4ms
rtt min/avg/max/mdev = 0.070/0.074/0.078/0.004 ms
traceroute vrf <name> [ipv4 | ipv6] <host>
Displays the route packets take to a network host utilizing VRF instance identified by <name>. When using the IPv4 or IPv6 option, display the route packets take to the for the given hosts IP address family. This option is useful when the host specified is a hostname rather than an IP address.