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.
Configuration
A VRF device is created with an associated route table. Network interfaces are then enslaved to a VRF device.
Create new VRF instance with <name>. The name is used when placing individual interfaces into the VRF.
Configured routing table <id> is 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.
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.
Zebra/Kernel route filtering
Zebra supports prefix-lists and Route Mapss to match routes received from other FRR components. The permit/deny facilities provided by these commands can be used to filter which routes zebra will install in the kernel.
Apply a route-map filter to routes for the specified protocol.
The following protocols can be used: any, babel, bgp, connected, eigrp, isis, kernel, ospf, rip, static, table
Note
If you choose any as the option that will cause all protocols that are sending routes to zebra.
Apply a route-map filter to routes for the specified protocol.
The following protocols can be used: any, babel, bgp, connected, isis, kernel, ospfv3, ripng, static, table
Note
If you choose any as the option that will cause all protocols that are sending routes to zebra.
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.
Routing
Note
VyOS 1.4 (sagitta) introduced dynamic routing support for VRFs.
Currently dynamic routing is supported for the following protocols:
The CLI configuration is same as mentioned in above articles. The only difference is, that each routing protocol used, must be prefixed with the vrf name <name> command.
Example
The following commands would be required to set options for a given dynamic routing protocol inside a given vrf:
BGP:
set vrf name <name> protocols bgp ...IS-IS:
set vrf name <name> protocols isis ...OSPF:
set vrf name <name> protocols ospf ...OSPFv3 (IPv6):
set vrf name <name> protocols ospfv3 ...Static:
set vrf name <name> protocols static ...
Operation
It is not sufficient to only configure a VRF but VRFs must be maintained, too. For VRF maintenance the following operational commands are in place.
Lists VRFs that have been created
[email protected]:~$ show vrf
VRF name state mac address flags interfaces
-------- ----- ----------- ----- ----------
blue up 00:53:12:d8:74:24 noarp,master,up,lower_up dum200,eth0.302
red up 00:53:de: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.
[email protected]:~$ show vrf name blue
VRF name state mac address flags interfaces
-------- ----- ----------- ----- ----------
blue up 00:53:12:d8:74:24 noarp,master,up,lower_up dum200,eth0.302
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
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
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, you 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 time 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.
Note
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
Displays the route packets taken to a network host utilizing VRF instance identified by <name>. When using the IPv4 or IPv6 option, displays the route packets taken to the given hosts IP address family. This option is useful when the host is specified as a hostname rather than an IP address.
Join a given VRF. This will open a new subshell within the specified VRF.
The prompt is adjusted to reflect this change in both config and op-mode.
[email protected]:~$ force vrf blue
[email protected](vrf:blue):~$
Example
VRF route leaking
The following example topology was built using EVE-NG.
VRF route leaking
PC1 is in the
defaultVRF and acting as e.g. a “fileserver”PC2 is in VRF
bluewhich is the development departmentPC3 and PC4 are connected to a bridge device on router
R1which is in VRFred. Say this is the HR department.R1 is managed through an out-of-band network that resides in VRF
mgmt
Configuration
set interfaces bridge br10 address '10.30.0.254/24' set interfaces bridge br10 member interface eth3 set interfaces bridge br10 member interface eth4 set interfaces bridge br10 vrf 'red' set interfaces ethernet eth0 address 'dhcp' set interfaces ethernet eth0 vrf 'mgmt' set interfaces ethernet eth1 address '10.0.0.254/24' set interfaces ethernet eth2 address '10.20.0.254/24' set interfaces ethernet eth2 vrf 'blue' set protocols static route 10.20.0.0/24 interface eth2 vrf 'blue' set protocols static route 10.30.0.0/24 interface br10 vrf 'red' set service ssh disable-host-validation set service ssh vrf 'mgmt' set system name-server 'eth0' set vrf name blue protocols static route 10.0.0.0/24 interface eth1 vrf 'default' set vrf name blue table '3000' set vrf name mgmt table '1000' set vrf name red protocols static route 10.0.0.0/24 interface eth1 vrf 'default' set vrf name red table '2000'
Operation
After committing the configuration we can verify all leaked routes are installed, and try to ICMP ping PC1 from PC3.
PCS> ping 10.0.0.1 84 bytes from 10.0.0.1 icmp_seq=1 ttl=63 time=1.943 ms 84 bytes from 10.0.0.1 icmp_seq=2 ttl=63 time=1.618 ms 84 bytes from 10.0.0.1 icmp_seq=3 ttl=63 time=1.745 msVPCS> show ip NAME : VPCS[1] IP/MASK : 10.30.0.1/24 GATEWAY : 10.30.0.254 DNS : MAC : 00:50:79:66:68:0f
VRF default routing table
[email protected]:~$ show ip route 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, r - rejected, b - backup C>* 10.0.0.0/24 is directly connected, eth1, 00:07:44 S>* 10.20.0.0/24 [1/0] is directly connected, eth2 (vrf blue), weight 1, 00:07:38 S>* 10.30.0.0/24 [1/0] is directly connected, br10 (vrf red), weight 1, 00:07:38
VRF red routing table
[email protected]:~$ show ip route vrf red 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, r - rejected, b - backup VRF red: K>* 0.0.0.0/0 [255/8192] unreachable (ICMP unreachable), 00:07:57 S>* 10.0.0.0/24 [1/0] is directly connected, eth1 (vrf default), weight 1, 00:07:40 C>* 10.30.0.0/24 is directly connected, br10, 00:07:54
VRF blue routing table
[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, r - rejected, b - backup VRF blue: K>* 0.0.0.0/0 [255/8192] unreachable (ICMP unreachable), 00:08:00 S>* 10.0.0.0/24 [1/0] is directly connected, eth1 (vrf default), weight 1, 00:07:44 C>* 10.20.0.0/24 is directly connected, eth2, 00:07:53
L3VPN VRFs
L3VPN VRFs bgpd supports for IPv4 RFC 4364 and IPv6 RFC 4659. L3VPN routes, and their associated VRF MPLS labels, can be distributed to VPN SAFI neighbors in the default, i.e., non VRF, BGP instance. VRF MPLS labels are reached using core MPLS labels which are distributed using LDP or BGP labeled unicast. bgpd also supports inter-VRF route leaking.
VRF Route Leaking
BGP routes may be leaked (i.e. copied) between a unicast VRF RIB and the VPN SAFI RIB of the default VRF for use in MPLS-based L3VPNs. Unicast routes may also be leaked between any VRFs (including the unicast RIB of the default BGP instance). A shortcut syntax is also available for specifying leaking from one VRF to another VRF using the default instance’s VPN RIB as the intemediary . A common application of the VRF-VRF feature is to connect a customer’s private routing domain to a provider’s VPN service. Leaking is configured from the point of view of an individual VRF: import refers to routes leaked from VPN to a unicast VRF, whereas export refers to routes leaked from a unicast VRF to VPN.
Note
Routes exported from a unicast VRF to the VPN RIB must be augmented by two parameters:
an RD / RTLIST
Configuration for these exported routes must, at a minimum, specify these two parameters.
Configuration
Configuration of route leaking between a unicast VRF RIB and the VPN SAFI RIB of the default VRF is accomplished via commands in the context of a VRF address-family.
Specifies the route distinguisher to be added to a route exported from the current unicast VRF to VPN.
Specifies the route-target list to be attached to a route (export) or the route-target list to match against (import) when exporting/importing between the current unicast VRF and VPN.The RTLIST is a space-separated list of route-targets, which are BGP extended community values as described in Extended Communities Attribute.
Enables an MPLS label to be attached to a route exported from the current unicast VRF to VPN. If the value specified is auto, the label value is automatically assigned from a pool maintained.
Specifies an optional route-map to be applied to routes imported or exported between the current unicast VRF and VPN.
Enables import or export of routes between the current unicast VRF and VPN.
Shortcut syntax for specifying automatic leaking from vrf VRFNAME to the current VRF using the VPN RIB as intermediary. The RD and RT are auto derived and should not be specified explicitly for either the source or destination VRF’s.
Operation
It is not sufficient to only configure a L3VPN VRFs but L3VPN VRFs must be maintained, too.For L3VPN VRF maintenance the following operational commands are in place.
Print active IPV4 or IPV6 routes advertised via the VPN SAFI.
BGP table version is 2, local router ID is 10.0.1.1, vrf id 0
Default local pref 100, local AS 65001
Status codes: s suppressed, d damped, h history, * valid, > best, = multipath,
i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 10.50.50.1:1011
*>i10.50.50.0/24 10.0.0.7 0 100 0 i
UN=10.0.0.7 EC{65035:1011} label=80 type=bgp, subtype=0
Route Distinguisher: 10.60.60.1:1011
*>i10.60.60.0/24 10.0.0.10 0 100 0 i
UN=10.0.0.10 EC{65035:1011} label=80 type=bgp, subtype=0
Print a summary of neighbor connections for the specified AFI/SAFI combination.
BGP router identifier 10.0.1.1, local AS number 65001 vrf-id 0
BGP table version 0
RIB entries 9, using 1728 bytes of memory
Peers 4, using 85 KiB of memory
Peer groups 1, using 64 bytes of memory
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd PfxSnt
10.0.0.7 4 65001 2860 2870 0 0 0 1d23h34m 2 10