Network Qos Policy (Ip-Interface Type) Functionality - Alcatel-Lucent 7210 SAS M OS Quality Of Service Manual

Overview

Network Qos Policy (ip-interface type) Functionality

When no ldp-local-fc-enable is in use, the following restrictions apply (compatible with behavior
in release 3.0 and before):
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Executing the command ldp-use-local-fc-enable, changes the mode of system behavior for
network qos policies, which allows more flexibility and removes some of the restrictions listed
above. After executing ldp-use-local-fc-enable, the following is possible:
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For LDP LSP traffic, the system uses a single policy (default network policy 2) to assign
the FC & profile to the packet. User cannot modify the EXP bits to FC mapping defined in
the default policy. Using MPLS EXP bits received in the packet to match the EXP bits
configured in the network policy, the policer to use is known. Thus, the system in effect
supports only a single system-defined classification policy for all IP interfaces for LDP
LSPs though policers with different rates can be used. It does not allow for the flexibility
to use different classification policy on different IP interfaces for LDP LSP traffic.
When using only LDP LSPs, user needs to be aware that the LSP EXP bits to FC
classification specified in the global policy is used by the system and not the classification
map specified in the network qos policy. Only the meter/policer is used from the network
qos policy. It does not cause any issues when only LDP is in use, though the way the
policies have been defined currently, its usage is not intuitive to user and can potentially
result in confusion.
There are only 32 unique hardware resources available to map the MPLS EXP bits to
profile values. Hence, in release 3.0, only 32 unique network policies could be associated
with IP interfaces, though the platform supports more number of IP interfaces. In other
words, in release 3.0, multiple IP interfaces needed to share network policies. Though it is
sufficient and meets most of the network deployment scenarios, some of the IP interfaces
need to share a single network policy. IP interfaces that share the policy will use the same
EXP bits to FC mapping.
If a user receives traffic on RSVP LSP and a LDP LSP with the same value in the EXP
bits and on the same IP interface, then potentially, the system can classify packets received
on a RSVP LSP to one FC and classify packets received on a LDP LSP to another
different FC. This is possible as LDP LSPs use the global network policy for classification
and RSVP LSPs used the network policy associated with the IP interface for classification.
If both of these policies specify the same EXP to FC mapping then there are no issues.
With release 3.0, it is good practice to setup the EXP bits to FC map, to be the same in the
default network policy and user-defined network policy when both LDP and RSVP
protocols are in use. This is required to ensure that all packets received on an IP interface
with a similar value of LSP EXP bit is classified to the same FC and a single policer is
used for all them. This ensures that all MPLS packets received with the same EXP bits
receive the same QoS treatment in the system.
LSPs setup using LDP uses a global mpls-lsp-exp-profile-map policy. By default, the
system assigns a default mpls-lsp-exp-profile-map policy. User has an option to change
7210 SAS M OS Quality of Service Guide