Alcatel-Lucent 7750 SR-OS, Configuration Manual

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IP Router Configuration
7750 SR OS Router Configuration Guide Page 33
QPPB and GRT Lookup
Source-address based QPPB is not supported on any SAP or spoke SDP interface of a VPRN
configured with the
grt-lookup command.
QPPB Interaction with SAP Ingress QoS Policy
When QPPB is enabled on a SAP IP interface the forwarding class of a packet may change from
fc1 , the original fc determined by the SAP ingress QoS policy to fc2, the new fc determined by
QPPB. In the ingress datapath SAP ingress QoS policies are applied in the first P chip and route
lookup/QPPB occurs in the second P chip. This has the implications listed below:
• Ingress remarking (based on profile state) is always based on the original fc (fc1) and sub-
class (if defined).
• The profile state of a SAP ingress packet that matches a QPPB route depends on the
configuration of
fc2 only. If the de-1-out-profile flag is enabled in fc2 and fc2 is not
mapped to a priority mode queue then the packet will be marked out of profile if its DE bit
= 1. If the profile state of
fc2 is explicitly configured (in or out) and fc2 is not mapped to a
priority mode queue then the packet is assigned this profile state. In both cases there is no
consideration of whether or not
fc1 was mapped to a priority mode queue.
• The priority of a SAP ingress packet that matches a QPPB route depends on several
factors. If the de-1-out-profile flag is enabled in
fc2 and the DE bit is set in the packet then
priority will be low regardless of the QPPB priority or fc2 mapping to profile mode queue,
priority mode queue or policer. If fc2 is associated with a profile mode queue then the
packet priority will be based on the explicitly configured profile state of fc2 (in profile =
high, out profile = low, undefined = high), regardless of the QPPB priority or fc1
configuration. If fc2 is associated with a priority mode queue or policer then the packet
priority will be based on QPPB (unless DE=1), but if no priority information is associated
with the route then the packet priority will be based on the configuration of
fc1 (if fc1
mapped to a priority mode queue then it is based on DSCP/IP prec/802.1p and if fc1
mapped to a profile mode queue then it is based on the profile state of fc1 ).
Table 2 summarizes these interactions.