Perform this task to configure dynamic point-to-point cross-connects.

Note	For dynamic cross-connects, LDP must be up and running.

Router# configure 
Router(config)# l2vpn 
Router(config-l2vpn)# xconnect group vlan_grp_1
Router(config-l2vpn-xc)# p2p vlan1
Router(config-l2vpn-xc-p2p)# interface HunGigE 0/0/0/0.1
Router(config-l2vpn-xc-p2p)# neighbor 10.0.0.1 pw-id 1
Router(config-l2vpn-xc-p2p-pw)# commit

configure
  l2vpn
   xconnect group vlan_grp_1
    p2p vlan1
    interface HunGigE 0/0/0/0.1
    neighbor 10.0.0.1 pw-id 1
!

In Ethernet port mode, both ends of a pseudowire are connected to Ethernet ports. In this mode, the port is tunneled over the pseudowire. The ingress PE transports frames received on a main interface or after the subinterface tags are removed when the packet is received on a subinterface. The VLAN manipulation is transported over the type 5 PW, whether tagged or untagged.

This figure shows a sample ethernet port mode packet flow:

/* PE1 configuration */
Router# configure 
Router(config)# l2vpn 
Router(config-l2vpn)# xconnect group grp1
Router(config-l2vpn-xc)# p2p xc1
Router(config-l2vpn-xc-p2p)# interface HundredGigE0/0/0/1.2
Router(config-l2vpn-xc-p2p)# neighbor 10.0.0.11 pw-id 222
Router(config-l2vpn-xc-p2p-pw)# commit

/* PE2 configuration */
Router# configure 
Router(config)# l2vpn 
Router(config-l2vpn)# xconnect group grp1
Router(config-l2vpn-xc)# p2p xc1
Router(config-l2vpn-xc-p2p)# interface HundredGigE0/1/0/3.2
Router(config-l2vpn-xc-p2p)# neighbor 10.0.0.13 pw-id 222
Router(config-l2vpn-xc-p2p-pw)# commit

/* PE1 configuration */
l2vpn
 xconnect group grp1
  p2p xc1
   interface HundredGigE0/0/0/1.2
   neighbor 10.0.0.11 pw-id 222

/* PE2 configuration */
l2vpn
 xconnect group grp1
  p2p xc1
   interface HundredGigE0/1/0/3.2
   neighbor 10.0.0.13 pw-id 222

Router# show l2vpn xconnect group grp1 detail
Group grp1, XC xc1, state is up; Interworking none
  AC: HundredGigE0/0/0/1.2, state is up
    Type VLAN; Num Ranges: 1
    VLAN ranges: [2, 2]
    MTU 1504; XC ID 0x840006; interworking none
    Statistics:
      packets: received 186, sent 38448
      bytes: received 12644, sent 2614356
      drops: illegal VLAN 0, illegal length 0
  PW: neighbor 10.0.0.11, PW ID 222, state is up ( established )
    PW class not set, XC ID 0xc0000004
    Encapsulation MPLS, protocol LDP
    Source address 10.0.0.13
    PW type Ethernet, control word disabled, interworking none
    PW backup disable delay 0 sec
    Sequencing not set

    PW Status TLV in use
      MPLS         Local                          Remote
      ------------ ------------------------------ -----------------------------
      Label        16026                          16031
      Group ID     0x4000280                      0x6000180
      Interface    HundredGigE0/0/0/1.2           HundredGigE0/1/0/3.2
      MTU          1504                           1504
      Control word disabled                       disabled
      PW type      Ethernet                       Ethernet
      VCCV CV type 0x2                            0x2
                   (LSP ping verification)        (LSP ping verification)
      VCCV CC type 0x6                            0x6
                   (router alert label)           (router alert label)
                   (TTL expiry)                   (TTL expiry)
      ------------ ------------------------------ -----------------------------
    Incoming Status (PW Status TLV):
      Status code: 0x0 (Up) in Notification message
    Outgoing Status (PW Status TLV):
      Status code: 0x0 (Up) in Notification message
    MIB cpwVcIndex: 3221225476
    Create time: 30/03/2021 16:30:58 (21:31:00 ago)
    Last time status changed: 30/03/2021 16:36:42 (21:25:16 ago)
    Statistics:
      packets: received 38448, sent 186
      bytes: received 2614356, sent 12644

In VLAN mode, each VLAN on a customer-end to provider-end link can be configured as a separate L2VPN connection using virtual connection (VC) type 4. In VLAN mode, each VLAN on a customer-end to provider-end link can be configured as a separate L2VPN connection using virtual connection (VC) type 4. VLAN-based (VC Type 4) pseudowires ensure a VLAN tag is transported over the pseudowire by pushing a dummy tag at the attachment circuit ingress. If the rewrite rule pushes two or more tags, a dummy tag is not needed because these VLAN tags are transported over the pseudowire. On the remote router, the dummy tag, if added, is removed before egress.

As illustrated in the following figure, the Ethernet PE associates an internal VLAN tag to the Ethernet port for switching the traffic internally from the ingress port to the pseudowire; however, before moving traffic into the pseudowire, it removes the internal VLAN tag.

At the egress VLAN PE, the PE associates a VLAN tag to the frames coming out of the pseudowire, and after switching the traffic internally, it sends out the traffic on an Ethernet trunk port.

Note	Because the port is in trunk mode, the VLAN PE doesn't remove the VLAN tag and forwards the frames through the port with the added tag.

Router# configure
Router(config)# l2vpn
Router(config-l2vpn)# pw-class VLAN
Router(config-l2vpn-pwc)# encapsulation mpls
Router(config-l2vpn-pwc-mpls)# transport-mode vlan
Router(config-l2vpn-pwc-mpls)# exit
Router(config-l2vpn-pwc)# exit
Router(config-l2vpn)# xconnect group grp1
Router(config-l2vpn-xc)# p2p xc1
Router(config-l2vpn-xc-p2p)# neighbor 10.0.0.11 pw-id 222
Router(config-l2vpn-xc-p2p-pw)# pw-class VLAN
Router(config-l2vpn-xc-p2p-pw)# commit

l2vpn
 pw-class VLAN
  encapsulation mpls
   transport-mode vlan
  !
 !
 xconnect group grp1
  p2p xc1
   neighbor 10.0.0.11 pw-id 222
    pw-class VLAN
   !
  !
 !
!

Router# show l2vpn xconnect group grp1 detail | i " PW type"
PW type Ethernet VLAN, control word disabled, interworking none
      PW type      Ethernet VLAN                  Ethernet VLAN

Configure the transport mode vlan passthrough command under the pw-class to negotiate a virtual connection (VC)-type 4 (Ethernet VLAN) PW, which transports whatever comes out of the AC after the VLAN tag manipulation specified by the rewrite command.The VLAN tag manipulation on the EFP ensures that there is at least one VLAN tag left on the frame because you need a VLAN tag on the frame if there are VC-type 4 PWs. No dummy tag 0 is added to the frame when you use the transport mode vlan passthrough command.

The Pseudowire Redundancy feature allows you to configure a redundant pseudowire that backs up the primary pseudowire. When the primary pseudowire fails, the PE router switches to the redundant pseudowire. You can elect to have the primary pseudowire resume operation after it becomes functional. The primary pseudowire fails when the PE router fails or when there is a network outage.

An autonomous system (AS) is a single network or group of networks that is controlled by a common system administration group and uses a single, clearly defined routing protocol.

As VPNs grow, their requirements expand. In some cases, VPNs need to reside on different autonomous systems in different geographic areas. In addition, some VPNs need to extend across multiple service providers (overlapping VPNs). Regardless of the complexity and location of the VPNs, the connection between autonomous systems must be seamless.

EoMPLS supports a single AS topology where the pseudowire connecting the PE routers at the two ends of the point-to-point EoMPLS cross-connects resides in the same autonomous system; or multiple AS topologies in which PE routers can reside on two different ASs using iBGP and eBGP peering.

The following figure illustrates MPLS over Inter-AS with a basic double AS topology with iBGP/LDP in each AS.

The Cisco 8000 load balances traffic when it is either not VLAN tagged or tagged with VLAN in supported formats.

The router performs load balancing on outgoing interfaces and bundle members in these scenarios:

1. Ethernet frames entering from a L2 main or sub interface may be

   • switched out to another L2 interface that is part of a bundle, or

   • routed out to L3 interfaces with MPLS encapsulation.

2. MPLS labeled PW and EVPN traffic entering from an L3 interface. After label disposition, the customer Ethernet frames may be

   • switched out to an L2 main or sub interface that is part of a bundle, or

   • routed out to L3 interfaces with MPLS encapsulation.

The router parses packets to identify the required headers for generating a load balance hash, which determines the path to route the traffic across the network. The hashing process varies based on whether the traffic is received on L2 or L3 interfaces.

For load balance hash on traffic received from L2 interfaces, refer to Hash for Traffic Received on L2 Interface.

For load balance hash on traffic received from L3 interfaces, refer to Hash for Traffic Received on L3 Interface.

The router performs BUM Traffic load balancing on outgoing interfaces and bundle members in these scenarios:

• Sending Traffic to an L2 Interface on bundle

• Sending Traffic over an MPLS PW

• Sending Traffic to EVPN MPLS Network

Sending Traffic to an L2 Interface on Bundle

When sending traffic to a L2 interface, the router does not perform load balancing over bundle members. Instead, it pins all traffic sent to an L2 main or sub-interface to a single bundle member. The selection of the bundle member is based on the main or sub-interface ID.

Sending Traffic over an MPLS PW

When BUM traffic is routed to an MPLS PW, the traffic is routed out to L3 interfaces. The router performs ECMP and bundle load balancing on the PW traffic. The hashing for load balancing is based on:

• PW VC label and flow label

• The 12 bytes of the PW payload. If control word (CW) is enabled, this includes a combination of 4 bytes of CW and 8 bytes of inner Ethernet MAC address.

Sending Traffic to EVPN MPLS Network

When BUM traffic is routed to an EVPN MPLS network, the traffic is encapsulated with:

• EVPN label

• ETREE leaf label or Ethernet Segment split horizon label

The MPLS encapsulated traffic is routed out to L3 interfaces. ECMP and bundle load balancing are performed on the EVPN MPLS encapsulated traffic. The hashing for load balancing is based on:

• EVPN label

• ETREE leaf label or Ethernet Segment split horizon label

• The 12 bytes of the PW payload. If CW is enabled, this includes a combination of 4 bytes of CW and 8 bytes of inner Ethernet MAC address.

In certain configurations, you may choose to disable the non-IP hash mode. When non-IP hash mode is disabled, the Ethernet MAC address of BUM traffic isn’t used to perform load balance hashing. This can impact how BUM traffic is distributed across the network, as the router relies on other available headers for hashing.

For traffic received on a L2 interface, hashing depends on the headers present in the packet stack. The router generates the load balance hash using the designated fields based on the packet stack headers.

When ethernet frames entering a L2 main or sub interface, the router identifies the IP header within the packet based on the packet stack headers. The router uses these packet stack headers to generate the hash for traffic received on the L2 interface.

IP Traffic on L2 Interface

An ethernet frame is classified as IP traffic if it meets the following requirements:

• The ethernet header contains no more than two VLAN tags.

• The ethernet header either has no VLAN tag or has VLAN tags in a supported format as listed in Supported VLAN Tag Formats for Load Balancing.

• No more than ten MPLS labels are placed in front of the IP header.

Non-IP Traffic on L2 Interface

All traffic that does not meet the description of IP traffic on L2 Interface is classified as non-IP traffic on L2 interface.

L2 Hash Fields

The L2 hash fields include the source and destination MAC addresses and the outer VLAN ID.

L3 Hash Fields

The L3 hash fields include the source and destination IP addresses and the source and destination ports of the layer 4 header.

IP Traffic Load Balancing

L2 hash fields were used in hashing. L3 hash fields were also included for limited traffic types.

Non-IP Traffic Load Balancing

Non-IP traffic on the L2 interface is load balanced using L2 hash fields.

If any of the designated fields are missing, the router replaces those field values with zeros.

For traffic received on a L3 interface hashing depends on several criteria, including the headers present in the packet stack and whether the Control Word (CW) and Flow Label (FL) are enabled on the pseudowire (PW).

When ethernet frames entering a L3 interface, the router identifies the IP header within the packet based on the packet stack headers.

IP over PW Traffic

An ethernet frame is classified as IP over PW traffic if it meets the following criteria:

• The frame contains an outer ethernet header and an inner ethernet header.

• No more than two MPLS labels are placed between the outer ethernet header and the inner ethernet header.

• There is no control word in front of the inner ethernet header.

• The inner ethernet header contains no more than two VLAN tags.

• The inner ethernet header has no VLAN tag or has VLAN tags in supported format as listed in Supported VLAN Tag Formats for Load Balancing.

• Behind the inner ethernet header, there are no more than ten MPLS labels placed in front of the IP header.

Non-IP over PW Traffic

All traffic that does not meet the IP over PW traffic criteria is classified as non-IP over PW traffic.

Inner Ethernet L2 Hash Fields

The inner ethernet L2 hash fields include the source and destination MAC addresses, and the first VLAN tag of the inner ethernet frame.

Inner Ethernet L3 Hash Fields

The inner ethernet L3 hash fields include L3 and L4 headers in the inner ethernet frame. They are source and destination IP addresses, the source and destination ports of the layer 4 header.

Control Word Presence L2 Hash Fields

The 12 bytes of the PW payload, which include 4 bytes of CW followed by the 8 bytes of inner ethernet frame MAC address.

MPLS Hash Fields of Outer Ethernet Frame

All MPLS labels in front of inner ethernet header.

PW Disposition Traffic Load Balancing

1. PW disposition traffic load balance when control word and flow label are both disabled.

   IP over PW Traffic Load Balancing

   IP over PW traffic load balance hash uses the inner ethernet L2 hash fields.

   Inner ethernet L3 hash fields are also added in the hashing for limited types of traffic.

   Non-IP over PW Traffic Load Balancing

   Non-IP over PW traffic load balance hash always uses the inner ethernet L2 hash fields.

2. PW disposition traffic load balance when control word is enabled and flow label disabled.

   In this case, all PW traffic is non-IP over PW traffic. Load balance hash uses control word presence L2 hash fields.

3. PW disposition traffic load balance when control word is disabled and flow label enabled.

   IP over PW traffic load balancing hash uses the inner ethernet L2 hash fields. Inner ethernet L3 hash fields are also added in the hashing for limited types of traffic.

   Non-IP over PW traffic load balancing hash uses the inner ethernet L2 hash fields.

4. PW disposition traffic load balance when control word and flow label are both enabled.

   In this case, all PW traffic is Non-IP over PW traffic.

   Non-IP over PW traffic load balance hash uses the control word presence L2 hash fields.