The following operations apply to lsp-ping and lsp-trace:
The sender node builds the Target FEC Stack TLV with a single FEC element corresponding to the node SID of the destination of the SR-ISIS or SR-OSPF tunnel.
A node SID label that is swapped at an LSR results in the return code of 8, ‟Label switched at stack-depth <RSC>” as per RFC 8029.
A node SID label that is popped at an LSR results in a return code of 3, ‟Replying router is an egress for the FEC at stack-depth <RSC>”.
The lsp-trace command is supported with the inclusion of the DSMAP TLV, the DDMAP TLV, or none (when none is configured, no Map TLV is sent). The downstream interface information is returned along with the egress label for the node SID tunnel and the protocol that resolved the node SID at the responder node.
Figure: Testing MPLS OAM with SR tunnels shows an example topology for an lsp-ping and lsp-trace for SR-ISIS node SID tunnel.
Considering this topology, the following is an output example for LSP-PING on DUT-A for target Node SID of DUT-F:
*A:Dut-A# oam lsp-ping sr-isis prefix 10.20.1.6/32 igp-instance 0 detail
LSP-PING 10.20.1.6/32: 80 bytes MPLS payload
Seq=1, send from intf int_to_B, reply from 10.20.1.6
udp-data-len=32 ttl=255 rtt=1220324ms rc=3 (EgressRtr)
---- LSP 10.20.1.6/32 PING Statistics ----
1 packets sent, 1 packets received, 0.00% packet loss
round-trip min = 1220324ms, avg = 1220324ms, max = 1220324ms, stddev = 0.000ms
The following is an output example for LSP-TRACE on DUT-A for target node SID of DUT-F (DSMAP TLV):
*A:Dut-A# oam lsp-trace sr-isis prefix 10.20.1.6/32 igp-instance 0 detail
lsp-trace to 10.20.1.6/32: 0 hops min, 0 hops max, 108 byte packets
1 10.20.1.2 rtt=1220323ms rc=8(DSRtrMatchLabel) rsc=1
DS 1: ipaddr=10.10.4.4 ifaddr=10.10.4.4 iftype=ipv4Numbered MRU=1496
label[1]=26406 protocol=6(ISIS)
2 10.20.1.4 rtt=1220323ms rc=8(DSRtrMatchLabel) rsc=1
DS 1: ipaddr=10.10.9.6 ifaddr=10.10.9.6 iftype=ipv4Numbered MRU=1496
label[1]=26606 protocol=6(ISIS)
3 10.20.1.6 rtt=1220324ms rc=3(EgressRtr) rsc=1
The following is an output example for LSP-TRACE on DUT-A for target node SID of DUT-F (DDMAP TLV):
*A:Dut-A# oam lsp-trace sr-isis prefix 10.20.1.6/32 igp-instance 0 downstream-map-tlv ddmap detail
lsp-trace to 10.20.1.6/32: 0 hops min, 0 hops max, 108 byte packets
1 10.20.1.2 rtt=1220323ms rc=8(DSRtrMatchLabel) rsc=1
DS 1: ipaddr=10.10.4.4 ifaddr=10.10.4.4 iftype=ipv4Numbered MRU=1496
label[1]=26406 protocol=6(ISIS)
2 10.20.1.4 rtt=1220324ms rc=8(DSRtrMatchLabel) rsc=1
DS 1: ipaddr=10.10.9.6 ifaddr=10.10.9.6 iftype=ipv4Numbered MRU=1496
label[1]=26606 protocol=6(ISIS)
3 10.20.1.6 rtt=1220324ms rc=3(EgressRtr) rsc=1