Generalized Multiprotocol Label Switching (GMPLS) Control of Ethernet Provider Backbone Traffic Engineering (PBB-TE)
Extracted elements (27)
PBB-TE defines the forwarding tuple as <ESP-MAC DA, ESP-MAC SA, ESP-VID> for unique connection identification, but the actual forwarding operation only uses ESP-MAC DA and ESP-VID in each direction. ESP-VIDs can be reused across ESPs, and there is no requirement that the two ESPs of a P2P TESI use the same VID.
PBB-TE is designed to be bidirectional and symmetrically routed: complete Ethernet protocol functionality is only guaranteed for bidirectional Eth-LSPs. The IEEE PBB-TE standard assumes co-routed ESPs for P2P TESIs to support TE service monitoring and operational simplicity.
Shared forwarding preserves the connectionless Ethernet capability of reusing destination forwarding entries for multiple sources sharing a common destination within a VLAN. It reduces forwarding table entries without changing actual paths and is invoked as a local policy decision based on label allocation.
The PBB-TE Ethernet Label is invariant within a domain (not swapped hop-by-hop), analogous to wavelength labels in transparent optical networks. This differs from traditional MPLS label swapping and reflects the Ethernet forwarding model.
Complete procedures for signaling bidirectional P2MP Eth-LSPs are out of scope for this document. Only P2MP in the source-to-destination direction using RFC 3473 and RFC 4875 procedures is described.
This document supports but does not modify the standard IEEE 802.1Qay data plane. GMPLS extensions are limited to the control plane for setup, teardown, protection, and recovery of ESPs and TESIs.
An IB-BEB receiving a PATH message MUST be able to determine the appropriate CBP that is the termination point of the Eth-LSP. IB-BEBs SHOULD advertise CNP TE Links in the GMPLS control plane, and RSVP-TE signaling SHOULD use CNP TE Links to identify the termination point of Eth-LSPs.
At least one I-SID Set Object MUST be present in the Service ID TLV.
If a bridge is not configured to use the ESP-VID value for PBB-TE ESPs, it MUST immediately generate an error: Routing problem (24) / Unacceptable label value (6).
If a PBB-TE Ethernet Label refers to a reserved IEEE MAC address (01-80-C2-00-00-00 to 01-80-C2-00-00-0F), a bridge encountering the mismatch MUST immediately generate an error: Routing problem (24) / Unacceptable label value (6).
If available VIDs are exhausted at the destination bridge, the bridge SHOULD generate a PathErr message with error code: Routing problem (24) and error value: MPLS Label allocation failure (9).
If I-SID information is provided and an ESP will support a known service, the IB-BEB MUST determine which PIP and associated CBP is configured with the I-SID and MUST assign that CBP to the ESP.
Intermediate bridges supporting the 802_1 PBB-TE switching type MUST NOT modify LABEL values. The LABEL object MUST be passed on unchanged, upstream, at each hop.
The data plane receiver MUST accept, and usually assigns, labels from its available label pool. Each PBB-TE Ethernet Label must be domain-wide unique, with a unique ESP-VID + ESP-MAC DA, for each direction.
The PBB-TE Ethernet Label format MUST be used for both P2P and P2MP Eth-LSPs. For P2P, the fields specify a VID and unicast MAC address; for P2MP, a VID and a group MAC address is carried.
To initiate a bidirectional Eth-LSP, the initiator MUST set the LSP encoding type to Ethernet (2), MUST set the LSP switching type to '802_1 PBB-TE' (value 40), and MUST set the UPSTREAM_LABEL to the ESP-VID1/ESP-MAC1 tuple.
A P2P PBB-TE Service Instance (TESI) is formed by two co-routed unidirectional ESPs with the same CBP MAC addresses, creating a bidirectional service. A GMPLS bidirectional LSP is analogous to a P2P TESI.
An Ethernet Switched Path (ESP) is a provisioned unidirectional traffic-engineered connectivity path identified by the 3-tuple <ESP-MAC DA, ESP-MAC SA, ESP-VID>. ESPs can be P2P or P2MP and are analogous to unidirectional LSPs.
The Service ID TLV is used to signal I-SID to ESP mapping. It can be carried in either the CALL_ATTRIBUTES object (type=3) via CALL signaling or the LSP_ATTRIBUTES object (type=2) via RSVP-TE PATH message.
A new Switching Type '802_1 PBB-TE' (value 40) has been assigned in the Switching Types registry of the GMPLS Signaling Parameters registry.
The Service ID TLV has been assigned value 3 in the Call Attributes TLV registry in the RSVP Parameters registry, carried in the CALL_ATTRIBUTES object (class=202, C-Type=1) defined by RFC 6001.
The Service ID TLV (Type 2) has been assigned in the Attributes TLV Space in the RSVP-TE Parameters registry, allowed on LSP_ATTRIBUTES (class=197, C-Type=1) but not on LSP_REQUIRED_ATTRIBUTES.
A GMPLS-controlled Ethernet PBB-TE system assumes UNI-attached users and devices may behave maliciously or incorrectly; intra-provider control traffic is trusted. Security requirements are equivalent to any GMPLS network, with access only via UNI, NNI, or protected management interfaces.
When in-band GMPLS signaling is used, control plane and data plane security affect each other. When out-of-band signaling is used, data-plane security is decoupled from the control plane. Where control-plane communications use 802.1AE MACsec point-to-point, no further security measures may be needed.
The I-SID Set Object contains: 8-bit Action (list=0, range=1), 8-bit Reserved, 16-bit Length, followed by one or more 32-bit entries each containing 8 reserved bits and a 24-bit I-SID value.
The PBB-TE Ethernet Label is a 64-bit generalized label: 4 reserved bits, 12-bit ESP VID, 48-bit ESP MAC address (split as highest 2 bytes in first word, remaining 4 bytes in second word). It is a domain-wide unique label.
The Service ID TLV carries a Type field (16 bits), Length field (variable, 16 bits), and one or more I-SID Set Objects. Type value is 3 in CALL_ATTRIBUTES and 2 in LSP_ATTRIBUTES.