Ethernet VPN (EVPN) is a solution that provides Ethernet multipoint services over MPLS networks. EVPN operates in contrast to the existing Virtual Private LAN Service (VPLS) by enabling control-plane based MAC learning in the core. In EVPN, PEs participating in the EVPN instances learn customer MAC routes in control-plane using MP-BGP protocol. Control-plane MAC learning brings a number of benefits that allow EVPN to address the VPLS shortcomings, including support for multihoming with per-flow load balancing.

EVPN provides the solution for network operators for the following emerging needs in their network:

• Data center interconnect operation (DCI)

• Cloud and services virtualization

• Remove protocols and network simplification

• Integration of L2 and L3 services over the same VPN

• Flexible service and workload placement

• Multi-tenancy with L2 and L3 VPN

• Optimal forwarding and workload mobility

• Fast convergence

• Efficient bandwidth utilization

To implement EVPN features, you need to understand the following concepts:

• Ethernet Segment (ES): An Ethernet segment is a set of Ethernet links that connects a multihomed device. If a multi-homed device or network is connected to two or more PEs through a set of Ethernet links, then that set of links is referred to as an Ethernet segment. The Ethernet segment route is also referred to as Route Type 4. This route is used for designated forwarder (DF) election for BUM traffic.

• Ethernet Segment Identifier (ESI): Ethernet segments are assigned a unique non-zero identifier, which is called an Ethernet Segment Identifier (ESI). ESI represents each Ethernet segment uniquely across the network.

• EVI: The EVPN instance (EVI) is represented by the virtual network identifier (VNI). An EVI represents a VPN on a PE router. It serves the same role of an IP VPN Routing and Forwarding (VRF), and EVIs are assigned import/export Route Targets (RTs). Depending on the service multiplexing behaviors at the User to Network Interface (UNI), all traffic on a port (all-to-one bundling), or traffic on a VLAN (one-to-one mapping), or traffic on a list/range of VLANs (selective bundling) can be mapped to a Bridge Domain (BD). This BD is then associated to an EVI for forwarding towards the MPLS core.

• EAD/ES: Ethernet Auto Discovery Route per ES is also referred to as Route Type 1. This route is used to converge the traffic faster during access failure scenarios. This route has Ethernet Tag of 0xFFFFFFFF.

• EAD/EVI: Ethernet Auto Discovery Route per EVI is also referred to as Route Type 1. This route is used for aliasing and load balancing when the traffic only hashes to one of the switches. This route cannot have Ethernet tag value of 0xFFFFFF to differentiate it from the EAD/ES route.

• Aliasing: It is used for load balancing the traffic to all the connected switches for a given Ethernet segment using the Route Type 1 EAD/EVI route. This is done irrespective of the switch where the hosts are actually learned.

• Mass Withdrawal: It is used for fast convergence during the access failure scenarios using the Route Type 1 EAD/ES route.

• DF Election: It is used to prevent forwarding of the loops. Only a single router is allowed to decapsulate and forward the traffic for a given Ethernet Segment.

At startup, PEs exchange EVPN routes in order to advertise the following:

• VPN membership: The PE discovers all remote PE members of a given EVI. In the case of a multicast ingress replication model, this information is used to build the PEs flood list associated with an EVI. BUM labels and unicast labels are exchanged when MAC addresses are learned.

• Ethernet segment reachability: In multihoming scenarios, the PE auto-discovers remote PE and their corresponding redundancy mode (all-active or single-active). In case of segment failures, PEs withdraw the routes used at this stage in order to trigger fast convergence by signaling a MAC mass withdrawal on remote PEs.

• Redundancy Group membership: PEs connected to the same Ethernet segment (multihoming) automatically discover each other and elect a Designated Forwarder (DF) that is responsible for forwarding Broadcast, Unknown unicast and Multicast (BUM) traffic for a given EVI.

EVPN can operate in single-homing or dual-homing mode. Consider single-homing scenario, when EVPN is enabled on PE, Route Type 3 is advertised where each PE discovers all other member PEs for a given EVPN instance. When an unknown unicast (or BUM) MAC is received on the PE, it is advertised as EVPN Route Type 2 to other PEs. MAC routes are advertised to the other PEs using EVPN Route Type 2. In multihoming scenarios, Route Types 1, 3, and 4 are advertised to discover other PEs and their redundancy modes (single-active or all-active). Use of Route Type 1 is to auto-discover other PE which hosts the same CE. The other use of this route type is to fast route unicast traffic away from a broken link between CE and PE. Route Type 4 is used for electing designated forwarder. For instance, consider the topology when customer traffic arrives at the PE, EVPN MAC advertisement routes distribute reachability information over the core for each customer MAC address learned on local Ethernet segments. Each EVPN MAC route announces the customer MAC address and the Ethernet segment associated with the port where the MAC was learned from and its associated MPLS label. This EVPN MPLS label is used later by remote PEs when sending traffic destined to the advertised MAC address.

The EVPN network layer reachability information (NLRI) provides different route types.

Route Type 5: IP Prefix Route

The IP prefixes are advertised independently of the MAC-advertised routes. With EVPN IRB, host route /32 is advertised using RT-2 and subnet /24 is advertised using RT-5.

Note	With EVPN IRB, host route /32 are advertised using RT-2 and subnet /24 are advertised using RT-5.

The MAC addresses learned on one device needs to be learned or distributed on the other devices in a VLAN. EVPN Software MAC Learning feature enables the distribution of the MAC addresses learned on one device to the other devices connected to a network. The MAC addresses are learnt from the remote devices using BGP.

Note	A device can contain up to 128K MAC address entries. A bridge domain on a device can contain up to 64K MAC address entries.

The above figure illustrates the process of software MAC learning. The following are the steps involved in the process:

1. Traffic comes in on one port in the bridge domain.

2. The source MAC address (AA) is learnt on the PE and is stored as a dynamic MAC entry.

3. The MAC address (AA) is converted into a type-2 BGP route and is sent over BGP to all the remote PEs in the same EVI.

4. The MAC address (AA) is updated on the PE as a remote MAC address.

The EVPN Out of Service feature enables you to control the state of bundle interfaces that are part of an Ethernet segment that have Link Aggregation Control protocol (LACP) configured. This feature enables you to put a node out of service (OOS) without having to manually shutdown all the bundles on their provider edge (PE).

Use the cost-out command to bring down all the bundle interfaces belonging to an Ethernet VPN (EVPN) Ethernet segment on a node. The Ethernet A-D Ethernet Segment (ES-EAD) routes are withdrawn before shutting down the bundles. The PE signals to the connected customer edge (CE) device to bring down the corresponding bundle member. This steers away traffic from this PE node without traffic disruption. The traffic that is bound for the Ethernet segment from the CE is directed to the peer PE in a multi-homing environment.

Note	EVPN cost-out is supported only on manually configured ESIs.

In the following topology, the CE is connected to PE1 and PE2. When you configure the cost-out command on PE1, all the bundle interfaces on the Ethernet segment are brought down. Also, the corresponding bundle member is brought down on the CE. Hence, the traffic for this Ethernet segment is now sent to PE2 from the CE.

To bring up the node into service, use no cost-out command. This brings up all the bundle interfaces belonging to EVPN Ethernet segment on the PE and the corresponding bundle members on the CE.

When the node is in cost-out state, adding a new bundle Ethernet segment brings that bundle down. Similarly, removing the bundle Ethernet segment brings that bundle up.

Use startup-cost-in command to bring up the node into service after the specified time on reload. The node will cost-out when EVPN is initialized and remain cost-out until the set time. If you execute evpn no startup-cost-in command while timer is running, the timer stops and node is cost-in.

The 'cost-out' configuration always takes precedence over the 'startup-cost-in' timer. So, if you reload with both the configurations, cost-out state is controlled by the 'cost-out' configuration and the timer is not relevant. Similarly, if you reload with the startup timer, and configure 'cost-out' while timer is running, the timer is stopped and OOS state is controlled only by the 'cost-out' configuration.

If you do a proc restart while the startup-cost-in timer is running, the node remains in cost-out state and the timer restarts.

Ethernet Connectivity Fault Management (CFM) is a service-level OAM protocol that provides tools for monitoring and troubleshooting end-to-end Ethernet services per VLAN. This includes proactive connectivity monitoring, fault verification, and fault isolation. CFM can be deployed in an EVPN network. You can monitor the connections between the nodes using CFM in an EVPN network.

EVPN Multiple Services per Ethernet Segment feature allows you to configure multiple services over single Ethernet Segment (ES). Instead of configuring multiple services over multiple ES, you can configure multiple services over a single ES.

You can configure the following services on a single Ethernet Bundle; you can configure one service on each sub-interface.

• Flexible cross-connect (FXC) service. It supports VLAN Unaware, VLAN Aware, and Local Switching modes.

  For more information, see Configure Point-to-Point Layer 2 Services chapter in L2VPN and Ethernet Services Configuration Guide for Cisco NCS 560 Series Routers.

• EVPN-VPWS Xconnect service

  For more information, see EVPN Virtual Private Wire Service (VPWS) chapter in L2VPN and Ethernet Services Configuration Guide for Cisco NCS 560 Series Routers.

• EVPN Integrated Routing and Bridging (IRB)

  For more information, see Configure EVPN IRB chapter in L2VPN and Ethernet Services Configuration Guide for Cisco NCS 560 Series Routers.

• Native EVPN

  For more information see, EVPN Features chapter in L2VPN and Ethernet Services Configuration Guide for Cisco NCS 560 Series Routers.

All these services are supported only on all-active multihoming scenario.

The following examples show EVI configuration under L2VPN bridge-domain for various VPLS-based networks:

Note	On reloading the Standby route processor (RP), traffic glitch occurs on the VPLS BUM traffic (< 1 second) in a single direction. Effective from release 7.1.1, this restrcition is not applicable.

l2vpn
 bridge group bg1
  bridge-domain bd-1-1
   interface GigabitEthernet
   !
   vfi vfi-1-1
    neighbor 200.0.2.1 pw-id 1200001
     mpls static label local 20001 remote 10001
    !
    neighbor 200.0.3.1 pw-id 1300001
     mpls static label local 30001 remote 10001
    !
    neighbor 200.0.4.1 pw-id 1400001
     mpls static label local 40001 remote 10001
    !   
  !
  evi 1 
!

l2vpn
bridge group bg1
bridge-domain bd-1-2
   interface GigabitEthernet
   !
   vfi vfi-1-2
    vpn-id 2
    autodiscovery bgp
     rd 101:2
     route-target 65530:200
     signaling-protocol bgp
      ve-id 11
      ve-range 16
     !
    !
   evi 2
  !

bridge-domain bd-1-4
   interface GigabitEthernet
   !
   vfi vfi-1-4
    neighbor 200.0.2.1 pw-id 1200004
    !
    neighbor 200.0.3.1 pw-id 1300004
    !
    neighbor 200.0.4.1 pw-id 1400004
    !
   evi 3
   !

Use the following commands to verify EVPN configuration and MAC advertisement. Verify EVPN status, AC status, and VFI status.

• show l2vpn bridge-domain

• show evpn summary

• show bgp rt l2vpn evpn

• show evpn evi

• show l2route evpn mac all

Router#show l2vpn bridge-domain bd-name bd-1-1
Mon Feb 20 21:03:40.244 EST
Legend: pp = Partially Programmed.
Bridge group: bg1, bridge-domain: bd-1-1, id: 0, state: up, ShgId: 0, MSTi: 0
  Aging: 300 s, MAC limit: 4000, Action: none, Notification: syslog
  Filter MAC addresses: 0
  ACs: 1 (1 up), VFIs: 1, PWs: 3 (2 up), PBBs: 0 (0 up), VNIs: 0 (0 up)
  List of EVPNs:
    EVPN, state: up
  List of ACs:
    Gi0/2/0/0.1, state: up, Static MAC addresses: 0, MSTi: 2
  List of Access PWs:
  List of VFIs:
    VFI vfi-1-1 (up)
      Neighbor 200.0.2.1 pw-id 1200001, state: up, Static MAC addresses: 0
      Neighbor 200.0.3.1 pw-id 1300001, state: down, Static MAC addresses: 0
      Neighbor 200.0.4.1 pw-id 1400001, state: up, Static MAC addresses: 0
  List of Access VFIs:
 When PEs are evpn enabled, pseudowires that are associated with that BD will be brought down. The VPLS BD pseudowires are always up.  

Verify the number of EVI’s configured, local and remote MAC-routes that are advertised.

Router#show evpn summary
Mon Feb 20 21:05:16.755 EST
-----------------------------
Global Information
-----------------------------
Number of EVIs                     : 6
Number of Local EAD Entries        : 0
Number of Remote EAD Entries       : 0
Number of Local MAC Routes         : 4
          MAC                      : 4
          MAC-IPv4                 : 0
          MAC-IPv6                 : 0
Number of Local ES:Global MAC      : 1
Number of Remote MAC Routes        : 0
          MAC                      : 0
          MAC-IPv4                 : 0
          MAC-IPv6                 : 0
Number of Remote SOO MAC Routes    : 0
Number of Local IMCAST Routes      : 4
Number of Remote IMCAST Routes     : 4
Number of Internal Labels          : 0
Number of ES Entries               : 1
Number of Neighbor Entries         : 4
EVPN Router ID                     : 200.0.1.1
BGP ASN                            : 65530
PBB BSA MAC address                : 0026.982b.c1e5
Global peering timer               :      3 seconds
Global recovery timer              :     30 seconds

Verify EVPN route-targets.

Router#show bgp rt l2vpn evpn
Mon Feb 20 21:06:18.882 EST
EXTCOMM         IMP/EXP
RT:65530:1               1 / 1
RT:65530:2               1 / 1
RT:65530:3               1 / 1
RT:65530:4               1 / 1
Processed 4 entries

Locally learnt MAC routes can be viewed by forwarding table 
show l2vpn forwarding bridge-domain mac-address location 0/0/cpu0
To Resynchronize MAC table from the Network Processors, use the command...
    l2vpn resynchronize forwarding mac-address-table location <r/s/i>

Mac Address    Type    Learned from/Filtered on    LC learned Resync Age/Last Change Mapped to       
-------------- ------- --------------------------- ---------- ----------------------
0033.0000.0001 dynamic Gi0/2/0/0.1                 N/A        20 Feb 21:06:59     N/A             
0033.0000.0002 dynamic Gi0/2/0/0.2                 N/A        20 Feb 21:06:59     N/A             
0033.0000.0003 dynamic Gi0/2/0/0.3                 N/A        20 Feb 21:04:29     N/A             
0033.0000.0004 dynamic Gi0/2/0/0.4                 N/A        20 Feb 21:06:59     N/A  

The remote routes learned via evpn enabled BD 
show l2vpn forwarding bridge-domain mac-address location 0/0$
To Resynchronize MAC table from the Network Processors, use the command...
    l2vpn resynchronize forwarding mac-address-table location <r/s/i>

Mac Address    Type    Learned from/Filtered on    LC learned Resync Age/Last Change Mapped to       
-------------- ------- --------------------------- ---------- ----------------------   
0033.0000.0001 EVPN    BD id: 0                    N/A        N/A                 N/A             
0033.0000.0002 EVPN    BD id: 1                    N/A        N/A                 N/A             
0033.0000.0003 EVPN    BD id: 2                    N/A        N/A                 N/A             
0033.0000.0004 EVPN    BD id: 3                    N/A        N/A                 N/A             

Verify EVPN MAC routes pertaining to specific VPN instance.

Router#show evpn evi vpn-id 1 mac
Mon Feb 20 21:36:23.574 EST

EVI        MAC address    IP address                   Nexthop                            Label   
---------- -------------- ---------------------------------------- ---------------------------------
1      0033.0000.0001      ::                       200.0.1.1                          45106

Verify L2 routing.

Router#show l2route evpn mac all
Mon Feb 20 21:39:43.953 EST
Topo ID  Mac Address    Prod   Next Hop(s)                             
-------- -------------- ------ ----------------------------------------
0        0033.0000.0001 L2VPN  200.0.1.1/45106/ME                      
1        0033.0000.0002 L2VPN  200.0.1.1/45108/ME                      
2        0033.0000.0003 L2VPN  200.0.1.1/45110/ME                      
3        0033.0000.0004 L2VPN  200.0.1.1/45112/ME   

Verifty EVPN route-type 2 routes.

Router#show bgp l2vpn evpn route-type 2
Mon Feb 20 21:43:23.616 EST
BGP router identifier 200.0.3.1, local AS number 65530
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0   RD version: 0
BGP main routing table version 21
BGP NSR Initial initsync version 1 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 200.0.1.1:1
*>i[2][0][48][0033.0000.0001][0]/104
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.1.1:2
*>i[2][0][48][0033.0000.0002][0]/104
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.1.1:3
*>i[2][0][48][0033.0000.0003][0]/104
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.1.1:4
*>i[2][0][48][0033.0000.0004][0]/104
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.3.1:1 (default for vrf bd-1-1)
*>i[2][0][48][0033.0000.0001][0]/104
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.3.1:2 (default for vrf bd-1-2)
*>i[2][0][48][0033.0000.0002][0]/104
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.3.1:3 (default for vrf bd-1-3)
*>i[2][0][48][0033.0000.0003][0]/104
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.3.1:4 (default for vrf bd-1-4)
*>i[2][0][48][0033.0000.0004][0]/104
                      200.0.1.1                     100      0 i

Processed 8 prefixes, 8 paths

Verify inclusive multicast routes and route-type 3 routes.

Router#show bgp l2vpn evpn route-type 3
Mon Feb 20 21:43:33.970 EST
BGP router identifier 200.0.3.1, local AS number 65530
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0   RD version: 0
BGP main routing table version 21
BGP NSR Initial initsync version 1 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 200.0.1.1:1
*>i[3][0][32][200.0.1.1]/80
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.1.1:2
*>i[3][0][32][200.0.1.1]/80
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.1.1:3
*>i[3][0][32][200.0.1.1]/80
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.1.1:4
*>i[3][0][32][200.0.1.1]/80
                      200.0.1.1                     100      0 i
Route Distinguisher: 200.0.3.1:1 (default for vrf bd-1-1)
*>i[3][0][32][200.0.1.1]/80
                      200.0.1.1                     100      0 i
*> [3][0][32][200.0.3.1]/80
                      0.0.0.0                                0 i
Route Distinguisher: 200.0.3.1:2 (default for vrf bd-1-2)
*>i[3][0][32][200.0.1.1]/80
                      200.0.1.1                     100      0 i
*> [3][0][32][200.0.3.1]/80
                      0.0.0.0                                0 i
Route Distinguisher: 200.0.3.1:3 (default for vrf bd-1-3)
*>i[3][0][32][200.0.1.1]/80
                      200.0.1.1                     100      0 i
*> [3][0][32][200.0.3.1]/80
                      0.0.0.0                                0 i
Route Distinguisher: 200.0.3.1:4 (default for vrf bd-1-4)
*>i[3][0][32][200.0.1.1]/80
                      200.0.1.1                     100      0 i
*> [3][0][32][200.0.3.1]/80
                      0.0.0.0                                0 i

To clear an L2VPN forwarding table at a specified location, you can use the clear l2vpn forwarding table command. When BVI is present in the bridge domain, you might experience traffic loss during the command execution. Refer the following work-around to resolve such issues.

When you encounter such issues, delete the BVI and roll back the action. As a result, the traffic on the BVI returns to normal state. The following example shows how to delete the BVI and perform roll back action:

Router#clear l2vpn forwarding table location 0/0/CPU0
Fri Mar 24 09:34:02.083 UTC
Router(config)#no int BVI100
Router(config)#commit
Router#roll configuration las 1
Wed Dec 16 18:26:52.869 UTC
Loading Rollback Changes.
Loaded Rollback Changes in 1 sec 
Committing

Note	We can also clear the forwarding table by shutting and unshutting the interface.

The Network Convergence using Core Isolation Protection feature allows the router to converge fast when remote links and local interfaces fail. This feature reduces the duration of traffic drop by rapidly rerouting traffic to alternate paths. This feature uses Object Tracking (OT) to detect remote link failure and failure of connected interfaces.

Tracking interfaces can only detect failure of connected interfaces and not failure of a remote router interfaces that provides connectivity to the core. Tracking one or more BGP neighbor sessions along with one or more of the neighbor’s address-families enables you to detect remote link failure.

Consider a traffic flow from CE1 to PE1. The CE1 can send the traffic either from Leaf1-1 or Leaf1-2. When Leaf1-1 loses the connectivity to both the local links and remote link, BGP sessions to both route reflectors (RRs) are down; the Leaf1-1 brings down the Bundle-Ether14 connected to CE1. The CE1 redirects the traffic from Leaf1-2 to PE1.

You can track the connected interfaces to identify the connected link failures. However, if there is a remote link failure, tracking connected interfaces does not identify the remote link failures. You must track BGP sessions to identify the remote link failure.

Note

When you configure the bgp graceful-restart command, unconfiguring a neighbor is considered as a non-gr event. This generates a BGP notification to the neighbor before the neighbor is unconfigured. On the remote router, if the track is configured for this neighbor, the track state is brought down immediately. However, certain configurations are treated as graceful reset reason and when unconfigured they supress the BGP notification to the neighbor. The route-reflector-client configuration under the neighbor or neighbor address-family is one of the examples. On the remote router, if the track is configured for this neighbor, the track state is not brought down immediately because a notification is not received. To overcome this situation, shutdown the neighbor before unconfiguring the neighbor. This generates a BGP notification to the neighbor, and any track configured for the neighbor is brought down immediately.

The router advertises the default-originate (0.0.0.0/0) towards the network fabric only upon receiving all the core routes. The router withdraws the advertisement of default-originate when the core is isolated. To avoid traffic drop, install the routes in the hardware. To accommodate an additional delay for the routes to be installed in the hardware, you can configure a timeout for the installed routes.

In this topology, PE3 advertises the default-originate to CE only when the PE3 session to RR is established and all the routes are received from the RR.

The EVPN Single-Active Multihoming for Anycast Gateway IRB feature supports single-active redundancy mode. In this mode, the provider edge (PE) nodes locally connected to an Ethernet Segment load balance traffic to and from the Ethernet Segment based on EVPN service instance (EVI). Within an EVPN service instance, only one PE forwards traffic to and from the Ethernet Segment (ES). This feature supports intersubnet scenario only.

Consider a topology where CE1 is multihomed to PE1 and PE2. Bundle Ethernet interfaces BE 1.1, BE 2.1, and the ingress interface must belong to the same switching domain on CE1. Enable host routing and configure anycast gateway IP address on both these peering PEs. PE1 and PE2 are connected to PE3 through MPLS core. PE3 has reachability of subnet 10.0.0.5/8 to both peering PEs. Peering PEs has reachability to PE3 subnet 192.0.2.1/24. CE2 is connected to PE3 through an Ethernet interface bundle. PE1 and PE2 advertise Type 4 routes, and then performs designated forwarder (DF) election. The non-DF blocks the traffic in both the directions in single-active mode.

Consider a traffic flow from CE1 to CE2. CE1 sends an address resolution protocol (ARP) broadcast request to both PE1 and PE2. Peering PEs performs designated forwarder (DF) election for shared ESI. If PE1 is the designated forwarder for the EVI, PE1 replies to the ARP request from CE1. PE2 drops the traffic from CE1. Thereafter, all the unicast traffic is sent through PE1. PE2 is set to stand-by or blocked state and traffic is not sent over this path. PE1 advertises MAC to PE3. PE3 always sends and receives traffic through PE1. PE3 sends the traffic to CE2 over Ethernet interface bundle. If BE1 fails, PE2 becomes the DF and traffic flows through PE2.

The EVPN Core Isolation Protection feature enables you to monitor and detect the link failure in the core. When a core link failure is detected in the provider edge (PE) device, EVPN brings down the PE's Ethernet Segment (ES), which is associated with access interface attached to the customer edge (CE) device.

EVPN replaces ICCP in detecting the core isolation. This new feature eliminates the use of ICCP in the EVPN environment.

Consider a topology where CE is connected to PE1 and PE2. PE1, PE2, and PE3 are running EVPN over the MPLS core network. The core interfaces can be Gigabit Ethernet or bundle interface.

When the core links of PE1 go down, the EVPN detects the link failure and isolates PE1 node from the core network by bringing down the access network. This prevents CE from sending any traffic to PE1. Since BGP session also goes down, the BGP invalidates all the routes that were advertised by the failed PE. This causes the remote PE2 and PE3 to update their next-hop path-list and the MAC routes in the L2FIB. PE2 becomes the forwarder for all the traffic, thus isolating PE1 from the core network.

When all the core interfaces and BGP sessions come up, PE1 advertises Ethernet A-D Ethernet Segment (ES-EAD) routes again, triggers the service carving and becomes part of the core network.

The EVPN Routing Policy feature provides the route policy support for address-family L2VPN EVPN. This feature adds EVPN route filtering capabilities to the routing policy language (RPL). The filtering is based on various EVPN attributes.

A routing policy instructs the router to inspect routes, filter them, and potentially modify their attributes as they are accepted from a peer, advertised to a peer, or redistributed from one routing protocol to another.

This feature enables you to configure route-policies using EVPN network layer reachability information (NLRI) attributes of EVPN route type 1 to 5 in the route-policy match criteria, which provides more granular definition of route-policy. For example, you can specify a route-policy to be applied to only certain EVPN route-types or any combination of EVPN NLRI attributes. This feature provides flexibility in configuring and deploying solutions by enabling route-policy to filter on EVPN NLRI attributes.

For information on these concepts, see Implementing Routing Policy.

Currently, this feature is supported only on BGP neighbor "in" and "out" attach points. The route policy can be applied only on inbound or outbound on a BGP neighbor.

The Support for DHCPv4 and DHCPv6 Client over the BVI feature allows you to configure DHCPv4 and DHCPv6 client on the Bridged Virtual Interface (BVI). You can configure a BVI, and request DHCP IPv4 or IPv6 address on the BVI. This allows your customer’s device to have initial connectivity to your network without user intervention in the field. After the device is connected to your network, the customer devices can push a node-specific configuration with static IP addresses on a different BVI for customer deployment.