Sr-Te Lsp Metric And Mtu Settings - Nokia 7705 SAR-W Series Manual

MPLS Guide
Ingress LER A programs a super NHLFE consisting of the label for the adjacency
over link C-D and points it to the already programmed NHLFE of the SR tunnel of its
local adjacency over link A-B. The latter NHLFE has the top label and also the
outgoing interface to send the packet to.
Note: The SR-TE LSP does not consume a separate backup super NHLFE; it only points
the single super NHLFE to the NHLFE of the SR shortest path tunnel it is riding. When the
latter activates its backup NHLFE, the SR-TE LSP will automatically forward over it.
LSR Node B already programmed the primary NHLFE for the adjacency SID over link
C-D and has the ILM with label 1001 point to it. In addition, node B will preprogram
the link-protect LFA backup next hop for link B-C and point the same ILM to it.
Note: There is no super NHLFE at node B because it only deals with the programming of
the ILM and primary and backup NHLFE of its adjacency SIDs and its local and remote node
SIDs.
VPRN service in node A forwards a packet to the VPN-IPv4 prefix X advertised by
BGP peer D.
path and for the FRR backup path at LSR B.
3.12.10.1
The MPLS module assigns an SR-TE LSP the maximum LSP metric value of
16 777 215 when the local router provides the hop-to-label translation for its path.
For an SR-TE LSP that uses PCE for path computation (pce-computation option
enabled) by the PCE and/or has its control delegated to the PCE (pce-control
enabled), the latter will return the computed LSP IGP or TE metric in the PCReq and
PCUpd messages. In both cases, the user can override the returned value by
configuring an admin metric using the command config>router>mpls>lsp>metric.
The MTU setting of an SR-TE LSP is derived from the MTU of the outgoing SR
shortest path tunnel it is using, adjusted with the size of the super NHLFE label stack
size.
The following are the details of this calculation:
SR_Tunnel_MTU = MIN {Cfg_SR_MTU, IGP_Tunnel_MTU – (1+ frr-overhead)×4}
3HE 18686 AAAB TQZZA
Figure 13 shows the resulting data path at each node for the primary

SR-TE LSP Metric and MTU Settings

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