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Example: Configuring Basic EVPN Active-Standby Multihoming

 

This example shows how to configure Ethernet VPN (EVPN) active-standby multihoming.

Requirements

This example uses the following hardware and software components:

  • Four MX Series 5G Universal Routing Platforms running Junos OS Release 14.1 (or later), with MPC interfaces, acting as provider edge (PE) and provider (P) routers.

  • Two customer edge (CE) devices.

Overview and Topology

Figure 1 illustrates a simple EVPN topology. Routers PE1 and PE2 are provider edge (PE) routers connected to multihomed customer edge (CE) Router CE1. Router PE3 is connected to CE Router CE2.

Figure 1: Simple EVPN Multihomed Topology
Simple EVPN Multihomed
Topology

The network has the following characteristics:

  • All PE and P routers are running OSPF.

  • There is an IBGP mesh between all PE routers.

  • MPLS (RSVP) LSPs are configured between all PE routers.

  • On Routers PE1 and PE2, each device’s CE-facing interface uses the same Ethernet Segment Identifier (ESI).

Configuration

CLI Quick Configuration

The configurations for each device is as follows:

CE1

CE2

PE1

PE2

PE3

P1

Verification

Confirm that the configuration is working properly.

Verifying OSPF

Purpose

Verify that OSPF is working properly.

Action

Verify that Router P1 has adjacencies established with all PE devices.

user@P1> show ospf neighbor

Meaning

Adjacencies have been established with the PE devices.

Verifying BGP

Purpose

Verify that BGP is working properly.

Action

Verify that MP-IBGP peerings are established using EVPN signaling between all PE devices.

user@PE1> show bgp summary
user@PE2> show bgp summary
user@PE3> show bgp summary

Meaning

EVPN-signaled MP-IBGP peerings have been established between all PE devices.

Verifying MPLS

Purpose

Verify that MPLS is working properly.

Action

Verify that MPLS LSPs are established between all PE devices.

user@PE1> show mpls lsp
user@PE2> show mpls lsp
user@PE3> show mpls lsp

Meaning

LSPs have been established between PE devices.

Verifying EVPN Configuration and Multihoming Status

Purpose

Verify that EVPN is configured properly.

Action

Verify that the EVPN routing instances and ESIs are configured and functioning correctly, and confirm that single-active multihoming is enabled.

user@PE1> show evpn instance EVPN-RI extensive
user@PE2> show evpn instance EVPN-RI extensive
user@PE3> show evpn instance EVPN-RI extensive

Meaning

From the outputs above, the following can be determined:

  • All three PE devices confirm that PE1 and PE2 are using single-active mode.

  • PE1 and PE2 are using the same ESI.

  • PE1 is elected as the designated forwarder (DF), and its CE-facing interface is put into a state of Up/Forwarding.

  • PE2 is elected as the backup designated forwarder (BDF), and its CE-facing interface is put into a state of Up/Blocking.

Verifying Route Exchange and ESI Autodiscovery

Purpose

Verify that EVPN signaling is working properly.

Action

Verify that autodiscovery and other signaling information is being shared between PE devices.

user@PE1> show route table EVPN-RI.evpn.0
user@PE2> show route table EVPN-RI.evpn.0
user@PE3> show route table EVPN-RI.evpn.0

Meaning

The outputs above show two EVPN route types:

  • Route Type 1: Ethernet Auto-Discovery (AD) Route - These routes are advertised on a per-EVI and per-ESI basis. Ethernet AD routes are required when a CE device is multihomed. When a CE device is single-homed, the ESI will be zero.

  • Route Type 3: Inclusive Multicast Ethernet Tag Route - This route sets up a path for broadcast, unknown unicast, and multicast (BUM) traffic from a PE device to the remote PE device on a per VLAN, per ESI basis.

The outputs above show the following information:

  • 1:192.168.x.x:10::112233445566778899::0/304 AD/EVI - This is the per-EVI AD Type 1 EVPN route. As the DF (and active device), Router PE1 has advertised this route to Routers PE2 and PE3.

  • 1:192.168.x.x:0::112233445566778899::FFFF:FFFF/304 AD/ESI - This is the per Ethernet segment AD Type 1 EVPN route. As the multihomed devices, Routers PE1 and PE2 have advertised this route to each other and to Router PE3.

  • 3:192.168.x.x:10::10::192.168.x.x/304 IM - This is the route used to set up a path for BUM traffic. Each PE device has advertised this route to the other PE device.

Verifying Ethernet Segment (ES) Route Exchange

Purpose

Verify that ES route information is being shared correctly.

Action

Verify that the local and advertised autodiscovery routes per Ethernet segment and the Ethernet segment routes are received.

user@PE1> show route table __default_evpn__.evpn.0
user@PE2> show route table __default_evpn__.evpn.0

Meaning

The outputs above show two EVPN route types:

  • Route Type 1: Ethernet Auto-Discovery (AD) Route - These routes are advertised on a per-EVI and per-ESI basis. Ethernet AD routes are required when a CE device is multihomed. When a CE device is single-homed, the ESI will be zero.

  • Route Type 4: Ethernet Segment Route - PE devices that are connected to the same Ethernet Segment will discover each other through the ES route.

The outputs above show the following information:

  • 1:192.168.x.x:0::112233445566778899::FFFF:FFFF/304 AD/ESI - This is the per Ethernet segment AD Type 1 EVPN route. In the outputs above, each PE device shows its own route.

  • 4:192.168.x.x:0::112233445566778899:192.168.x.x/304 ES - This is the ES route for the local ESI. In the outputs above, each PE device shows both its own route and the one advertised by the other PE device.