Tag :: Pseudowire

The Flexible Encapsulation (FlexEncap) feature is used in conjunction with pseudowire, L2, and L3 subinterfaces to match on incoming VLAN tags and retain and/or rewrite them on egress. In the case where VLAN tags are swapped or pushed, the class of service (CoS) field of any new VLAN tag is set based on the configured traffic-class to CoS mapping. That is, based on the traffic class the incoming packet traversed through, the CoS of all VLAN tags of the outgoing packet is determined by the result of the traffic-class to CoS map.

EVPN MPLS VPWS (RFC 8214) provides the ability to forward customer traffic to / from a given attachment circuit (AC) without any MAC lookup / learning. The basic advantage of VPWS over an L2 EVPN is the reduced control plane signalling due to not exchanging MAC address information. In contrast to LDP pseudowires, EVPN MPLS VPWS uses BGP for signalling. Port based and VLAN based services are supported.

Flexible cross-connect service is an extension of EVPN MPLS Virtual Private Wire Service (VPWS) (RFC 8214). It allows for multiplexing multiple attachment circuits across different Ethernet Segments and physical interfaces into a single EVPN VPWS service tunnel while still providing single-active and all-active multi-homing.

EOS supports the ability to match on a single VLAN tag (example: encapsulation dot1q vlan 10) or a VLAN tag pair (example: encapsulation dot1q vlan 10 inner 20) to map matching packets to an interface. In this case, the encapsulation string is considered consumed by the mapped interface before forwarding, which means that the tags are effectively removed from the incoming packet for the purposes of any downstream forwarding.

This feature allows encapsulating (and decapsulating) L2 traffic from a given interface or subinterface over a GRE tunnel. An MPLS label is added to identify the ingress interface (similar to MPLS pseudowires) and the GRE tunnel is used to transport the packets to a remote endpoint.

Pseudowires can be used to connect geographically separated L2 networks by emulating an L2 point-to-point connection over a MPLS backbone. While each pseudowire can be configured manually, a L2VPN solution can be used to perform auto-discovery and signaling of the desired pseudowires. VPWS (Virtual Private Wire Service) can be used for auto-discovery and signaling of point-to-point pseudowires. The pseudowires in each VPWS instance can be signaled by LDP or BGP. When signaled using BGP, there are two VPWS sub-types:

The LDP pseudowire feature provides support for emulating Ethernet connections over a Multiprotocol Label Switching (MPLS) network using the extension of the MPLS Label Distribution Protocol (LDP)

The alternate LDP pseudowire feature enables users to configure an alternate pseudowire to the existing (primary) pseudowire for a given patch. Preference is initially given to the primary pseudowire.

This feature allows configuring user defined tunnel RIBs for the resolution of LDP pseudowire endpoints. User

User-defined TPIDs allow an arbitrary TPID (Tag Protocol Identifier) to be used with a FlexEncap specification. A TPID is used in Ethernet frames to identify the encapsulation protocol, where standard values like 0x8100 (for IEEE 802.1q VLAN tagging) and 0x88a8 (for IEEE 802.1ad Q-in-Q) are commonly used. However, some network equipment may use non-standard or legacy values such as 0x9100. This feature allows FlexEncap subinterfaces to be configured with an arbitrary TPID to allow interfacing with networking equipment that uses values besides 0x8100 and 0x88a8.

The feature will provide the ability to error disable local interfaces in a BGP VPWS pseudowire when the remote interface is shutdown or whenever we do not receive a response from BGP.