P2MP LSP references in this section apply only to the 7210 SAS-Mxp, 7210 SAS-R6, 7210 SAS-R12, 7210 SAS-Sx/S 1/10GE (standalone and standalone-VC mode), and 7210 SAS-T.
This section provides a generalized description of the LSP diagnostics tools. Users should take into account the following restrictions when reading the information contained in this section:
The 7210 SAS does not support LDP LER ECMP. Descriptions of LDP ECMP as an LER node in LSP diagnostics: LSP ping and trace do not apply to 7210 SAS platforms.
LDP LSR ECMP is only supported on 7210 SAS-Mxp, 7210 SAS-Sx/S 1/10GE, 7210 SAS-Sx 10/100GE, 7210 SAS-R6, and 7210 SAS-R12. The description on LDP ECMP as LSR node applies only to these platforms.
7210 SAS platforms support LDP and BGP 3107 labeled routes. The 7210 SAS does not support LDP FEC stitching to BGP 3107 labeled route to LDP FEC stitching and vice-versa. The following description about stitching of BGP 3107 labeled routes to LDP FEC is provided to describe the behavior in an end-to-end network solution deployed using 7210 SAS and 7x50 nodes, with 7210 SAS nodes acting as the LER node.
7210 SAS platforms do not support the use of ECMP routes for BGP 3107 labeled routes. The feature description is provided in this section for completeness and better understanding of the behavior in the end-to-end network solution deployed using 7210 SAS and 7750 nodes.
The router LSP diagnostics are implementations of LSP ping and LSP trace based on RFC 4379, Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures. LSP ping provides a mechanism to detect data plane failures in MPLS LSPs. LSP ping and LSP trace are modeled after the ICMP echo request/reply used by ping and trace to detect and localize faults in IP networks.
For a specific LDP FEC, RSVP P2P LSP, or BGP IPv4 Label Router, LSP ping verifies whether the packet reaches the egress label edge router (LER), while in LSP trace mode, the packet is sent to the control plane of each transit label switched router (LSR) which performs various checks to see if it is actually a transit LSR for the path.
The downstream mapping TLV is used in LSP ping and LSP trace to provide a mechanism for the sender and responder nodes to exchange and validate interface and label stack information for each downstream of an LDP FEC or an RSVP LSP and at each hop in the path of the LDP FEC or RSVP LSP.
Two downstream mapping TLVs are supported: the original Downstream Mapping (DSMAP) TLV defined in RFC 4379 and the new Downstream Detailed Mapping (DDMAP) TLV defined in RFC 6424.
When the responder node has multiple equal cost next-hops for an LDP FEC prefix, the downstream mapping TLV can further be used to exercise a specific path of the ECMP set using the path-destination option. The behavior in this case is described in the following ECMP subsection.