10.4. Configuring an EVPN Service With CLI

10.4.3.1. EVPN-MPLS r-VPLS Without Multihoming

The first scenario describes r-VPLS support including IP route advertisement (BGP-EVPN route type 5) with EVPN tunnel interfaces without multihoming. VPLS 101 does not have a connected host, but the linked VPRN has SAP 1/2/1:10. Figure 175 shows an example of topology used for r-VPLS with an EVPN tunnel but without multihoming. IP prefixes are advertised.

Figure 175:  r-VPLS With EVPN Tunnel, Without Multihoming 

The initial configuration includes the following:

BGP is configured for address family EVPN on PE-2 and PE-3. The BGP configuration on PE-2 is as follows. The BGP configuration on PE-3 is similar.

The CEs are connected to SAP 1/2/1:10 in VPRN 10. r-VPLS 101 is bound to VPRN 10 and VPRN 10 has a dedicated interface “int-evi-101” for the EVPN tunnel. In general, if only one route target (RT) is used for import and export in the EVPN-VPLS, it is best to add the EVI and have the route distinguisher (RD) and RT auto-derived from the EVI; this simplifies the configuration and reduces the chance of errors. The service configuration on PE-2 is as follows:

In the preceding configuration:

The configuration is similar on PE-3. The RD must be different on PE-2 and PE-3; this is automatically the case when the RD is auto-derived from the configured EVI, as in the example. The RD on PE-2 is 192.0.2.2:101; on PE-3, the RD is 192.0.2.3:101.

PE-3 receives the following BGP-EVPN IP prefix route for prefix 172.16.2.0/24 from PE-2:

GW IP 0.0.0.0 is an indication that an EVPN tunnel is in use. With EVPN tunnels, no IRB IP address needs to be configured in the VPRN. EVPN tunnels make provisioning easier to automate and save IP addresses from the tenant IP space.

The BGP tunnel encapsulation is MPLS, but the MPLS label in the debug message is not the same as in the service, because the router strips the extra four lowest bits to get the 20-bit MPLS label. In the debug message, the label is 8388464. This is because the debug message is shown before the router can parse the label field and see if it corresponds to an MPLS label (20 bits). The MPLS label is calculated by dividing the label value by 24 (16), as follows: 8388464/16 = 524279.

The MAC next-hop extended community 04:0b:ff:ff:ff:a2 is the MAC address of the interface “int-evi-101” in VPRN 10 on PE-2, as follows:

The routing table for VPRN 10 on PE-3 contains the route for prefix 172.16.2.0/24 as the BGP-EVPN route with next-hop “int-evi-101” and interface name “ET-04:0b:ff:ff:ff:a2” (ET stands for EVPN Tunnel), as follows:

The forwarding database (FDB) for VPLS 101 on PE-3 shows an entry for MAC address 04:0b:ff:ff:ff:a2 that is learned via EVPN. The MAC address is static (S) and protected (P). The MPLS label is 524279.

When the CEs have IPv6 addresses, the VPRN configuration is similar on the PEs, but the ipv6 context must be enabled on the EVPN tunnel interface so that the router can advertise and process BGP-EVPN type 5 routes with IPv6 prefixes. The configuration of VPLS is identical for IPv4 and IPv6.

When advertising IPv6 prefixes, the GW IP field for route type 5 is always populated with the IPv6 address of the r-VPLS interface. In this example, because no specific IPv6 global address is configured, the GW IP will be populated with the auto-created link local address. The following BGP update is received by PE-3 for IPv6 prefix 2001:db8:16::2:0/120:

The IPv6 route table on PE-3 is as follows:

10.4.3.2. EVPN-MPLS r-VPLS With All-Active Multihoming

Figure 176 shows an example of the topology with all-active multihoming Ethernet segment (ES) “ESI-23”.

Figure 176:  EVPN-MPLS r-VPLS With All-Active Multihoming ES 

BGP is configured between PE-2, PE-3, and PE-4 for address family EVPN. The configuration on PE-2 is as follows:

All-active multihoming Ethernet segment “ESI-23” is configured on PE-2 and PE-3 as follows:

The following services are configured on the PEs:

The services are configured on PE-2 as follows. The configuration on PE-3 and PE-4 is similar.

The IPv6 VRRP backup address is in the same subnet as the link local address of the interface “int-evi-202”. The IPv6 address can be set as preferred. Also for IPv6, router advertisement must be enabled and configured to use the virtual MAC address.

10.4.3.3. EVPN-MPLS r-VPLS With Single-Active Multihoming

Figure 177 shows an example of topology with single-active multihoming ES “ESI-23”. The difference between this figure and Figure 176 is that in Figure 177 the ES is single-active and SDPs are used instead of a LAG.

Figure 177:  EVPN-MPLS r-VPLS With Single-Active Multihoming 

The configuration is modified as follows:

The service configuration on PE-2 is as follows. The configuration on PE-3 is similar. No changes are required on PE-4.

PE-2 is the designated forwarder (DF) in the single-active ES, as shown in the following output:

When traffic is sent between CE-11 and CE-41, the FDB on PE-2 is as follows, where MAC address 00:00:01:00:00:11 corresponds to CE-11 and is learned on spoke-SDP 21:20, and MAC address 00:00:04:00:00:41 corresponds to CE-41 and his advertised by PE-4 in an EVPN-MAC route.

When the SDP between MTU-1 and DF PE-2 goes down, traffic from CE-41 to CE-11 is forwarded by PE-4 to DF PE-2. PE-2 cannot forward the packets to CE-11 directly and will forward the packets to its ES peer PE-3. PE-3 will forward to CE-11 even if the MAC SA matches its own vMAC. Virtual MACs bypass the r-VPLS interface protection, so traffic can be forwarded between the PEs without being dropped.