Alcatel-Lucent 7450 Manual page 70

MPLS-TP Maintenance Identifiers
In non-IP environments, LSP ping can be encapsulated with no IP/UDP headers in a G-ACh and
use a source address TLV to identify the source node, using forward and reverse LSP or PW
associated channels on the same LSP or PW for the echo request and reply packets. In this case, no
IP/UDP headers are included in the LSP-Ping packets.
The 7750 support the following encapsulations:
•
•
•
LSP Ping and VCCV Ping for MPLS-TP use two new FEC sub-types in the target FEC stack in
order to identify the static LSP or static PW being checked. These are the Static LSP FEC sub-
type, which has the same format as the LSP identifier described above, and the Static PW FEC
sub-type,. These are used in-place of the currently defined target FEC stack sub-TLVs.
In addition, MPLS-TP uses a source/destination TLV to carry the MPLS-TP global-id and node-id
of the target node for the LSP ping packet, and the source node of the LSP ping packet.
LSP Ping and VCCV-Ping for MPLS-TP can only be launched by the LER or T-PE. The replying
node therefore sets the TTL of the LSP label or PW label in the reply packet to 255 to ensure that
it reaches the node that launched the LSP ping or VCCV Ping request.
Downstream Mapping Support
RFC 4379 specifies four address types for the downstream mapping TLV for use with IP
numbered and unnumbered interfaces:
Type #
1
2
3
4
RFC 6426 adds address type 5 for use with Non IP interfaces, including MPLS-TP interfaces. In
addition, this RFC specifies that type 5 must be used when non-IP ACH encapsulation is used for
LSP Trace.
It is possible to send and respond to a DSMAP/DDMAP TLV in the LSP Trace packet for
numbered IP interfaces as per RFC4379. In this case, the echo request message contains a
downstream mapping TLV with address type 1 (IPv4 address) and the IPv4 address in the
DDMAP/DSMAP TLV is taken to be the IP address of the IP interface that the LSP uses. The LSP
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IP encapsulation with ACH for PWs (as per VCCV type 1).
IP encapsulation without ACH for LSPs using labeled encapsulation
Non-IP encapsulation with ACH for both PWs and LSPs.
Address Type K Octets Reference
IPv4 Numbered
IPv4 Unnumbered
IPv6 Numbered
IPv6 Unnumbered
16 RFC 4379
16 RFC 4379
40 RFC 4379
28 RFC 4379
7450 ESS MPLS Guide