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Merge pull request sonic-net#42 from BRCM-SONIC/hasan-brcm-patch-1
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Add BGP VRF and route-leak section in SONiC command reference guide
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@dks19
dks19 authored Oct 1, 2020
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* [Configuration Commands](#bgp-error-handling-config-commands)
* [Show Commands](#bgp-error-handling-show-commands)
* [Clear Commands](#bgp-error-handling-clear-commands)
* [BGP VRF Configuration And Show Commands](#bgp-vrf-configuration-and-show-commands)
* [Configuration Commands](#bgp-vrf-config-commands)
* [BGP VRF Route Leak](#bgp-vrf-route-leak)
* [Show Commands](#bgp-vrf-route-leak-show-commands)
* [EVPN Configuration And Show Commands](#evpn-configuration-and-show-commands)
* [Enable EVPN between BGP Neighbors](#enable-evpn-between-bgp-neighbors)
* [EVPN Configuration Commands](#evpn-configuration-commands)
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root@sonic:~# clear ip route not-installed
```

# BGP VRF Configuration And Show Commands
This section provides high level config and show commands for BGP VRF
configuration and VRF route leak via BGP.

Please refer to "VRF configuration and show commands" section for details on
how to create VRFs in SONiC.

## Configuration Commands

BGP VRF instance for a given VRF can be configured using IS-CLI as shown below.
Autonomous-System (AS) number for the BGP VRF instance is not mandated to same
as of default BGP VRF instance.

Below example configures BGP instance for Vrf-red, configures a neighbor, and
redistributes connected routes into BGP VRF instance.

```
sonic(config)# router bgp 65535 vrf Vrf-red
sonic(config-router-bgp)# router-id 192.168.1.1
sonic(config-router-bgp)# neighbor 10.20.30.40
sonic(config-router-bgp-neighbor)# remote-as external
sonic(config-router-bgp-neighbor)# address-family ipv4 unicast
sonic(config-router-bgp-neighbor-af)# activate

sonic(config-router-bgp)# address-family ipv4 unicast
sonic(config-router-bgp-af)# redistribute connected
```

It is recommended to configure router-id for the BGP VRF instance(s) in order
to avoid router-id reselection when IP addresses are unconfigured in the VRF.

IPv4 unicast, IPv6 unicast, and L2VPN EVPN address-families are
supported in the BGP VRF instances. Details on using L2VPN EVPN
address-family is described in the next BGP EVPN section.

BGP VRF instance can be created without creating default BGP VRF instance.
However, deletion of default BGP VRF instance is restricted if non-default BGP
VRF instance(s) are present. All non-default BGP VRF instances are required to
be deleted before deleting BGP default VRF instance.


## BGP VRF Route Leak
Routes can be leaked from one VRF to another using BGP VRF route leak feature
described in this section.

Use the 'import' command in corresponding address-family of BGP VRF instance to
import routes from the given source VRF. In the example below, BGP Vrf-red
instance is configured to import IPv4 and IPv6 routes from BGP Vrf-blue.
```
sonic(config)# router bgp 20 vrf Vrf-red
sonic(config-router-bgp)# address-family ipv4 unicast
sonic(config-router-bgp-af)# import vrf Vrf-blue

sonic(config-router-bgp)# address-family ipv6 unicast
sonic(config-router-bgp-af)# import vrf Vrf-blue

```

Import of routes from multiple BGP VRF instances is allowed.

Route-map can be applied for the imported leaked routes as shown below.

```
sonic(config)# router bgp 20 vrf Vrf-red
sonic(config-router-bgp)# address-family ipv4 unicast
sonic(config-router-bgp-af)# import vrf route-map my-import-filter
sonic(config-router-bgp-af)# import vrf Vrf-red
sonic(config-router-bgp-af)#
```

Configured import route-map filters routes from all of the configured
import-VRFs. In case specific routes from specific VRF are required to be
filtered, match-vrf clause in the route-map can be used.

Note that above BGP VRF import commands leak the prefixes, including connected
subnets, from one vrf to another. Leaking of connected subnets may incur
sub-optimal forwarding for the inter-vrf traffic through the CPU (slow) path.
It is therefore recommended to always leak the routes which have remote
next-hops instead of leaking the connected subnets.


## Show Commands
In order to show routes from a given VRF instance, 'vrf' option can be
specified to the regular bgp and ip route show commands.

Below commands show BGP routes in the given BGP VRF instance:

```
sonic# show ip bgp vrf Vrf-red
BGP table version is 9, local router ID is 169.100.1.1, vrf id 91
Default local pref 100, local AS 10
Status codes: s suppressed, d damped, h history, * valid, > best, = multipath, # not installed in hardware
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
*> 1.1.1.1/32 0.0.0.0@0< 0 32768 ?
*> 1.2.1.1/32 0.0.0.0@0< 0 32768 ?
*> 4.1.1.1/32 fe80::5054:ff:fe8d:7741@0<
*> 8.0.0.0/24 fe80::5054:ff:fe8d:7741@0<
* 10.59.128.0/20 fe80::5054:ff:fe8d:7741@0<
*> 51.52.0.0/31 0.0.0.0@0< 0 32768 ?
*> 155.100.1.0/24 0.0.0.0 0 32768 ?
*> 169.100.1.0/24 0.0.0.0 0 32768 ?
*> 200.2.1.0/24 0.0.0.0@0< 0 32768 ?

Displayed 9 routes and 13 total paths
sonic#

```

```
sonic# show bgp vrf Vrf-red ipv6
BGP table version is 3, local router ID is 169.100.1.1, vrf id 91
Default local pref 100, local AS 10
Status codes: s suppressed, d damped, h history, * valid, > best, = multipath, # not installed in hardware
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
*> 1550:100:1::/80 :: 0 32768 ?
*> 1690:100:1::/64 :: 0 32768 ?
*> 2000:200::/64 ::@0< 0 32768 ?

Displayed 3 routes and 3 total paths
sonic#
```


Below command shows routes from the RIB for the specified VRF:
```
sonic# show ip route vrf 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 route, r - rejected route, # - not installed in hardware
VRF Vrf-red:
B>* 1.1.1.1/32 [200/0] is directly connected, Loopback10(vrf default), 01:33:30
B>* 1.2.1.1/32 [200/0] is directly connected, Loopback11(vrf default), 01:33:30
B>* 4.1.1.1/32 [200/0] via fe80::5054:ff:fe8d:7741, Ethernet0(vrf default), 01:33:29
B>* 8.0.0.0/24 [200/0] via fe80::5054:ff:fe8d:7741, Ethernet0(vrf default), 01:33:29
B>* 10.59.128.0/20 [200/0] is directly connected, eth0(vrf default), 01:33:30
B>* 51.52.0.0/31 [200/0] is directly connected, Vlan4090(vrf default), 01:33:30
C>* 155.100.1.0/24 is directly connected, Vlan100, 01:33:52
C>* 169.100.1.0/24 is directly connected, Vlan1000, 01:33:52
B>* 200.2.1.0/24 [200/0] is directly connected, Vlan200(vrf default), 01:33:30
sonic#

```

# EVPN Configuration And Show Commands

The following sections provide the basic configuration needed to use EVPN as the control plane for VXLAN.
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