VPRN Features
Page 1074 7750 SR OS Services Guide
DSCP Marking
Specific DSCP, forwarding class, and Dot1P parameters can be specified to be used by every
protocol packet generated by the node. This enables prioritization or de-prioritization of every
protocol (as required). The markings effect a change in behavior on ingress when queuing. For
example, if OSPF is not enabled, then traffic can be de-prioritized to best effort (be) DSCP. This
change de-prioritizes OSPF traffic to the CPU complex.
DSCP marking for internally generated control and management traffic by marking the DSCP
value should be used for the given application. This can be configured per routing instance. For
example, OSPF packets can carry a different DSCP marking for the base instance and then for a
VPRN service. ISIS and ARP traffic is not an IP-generated traffic type and is not configurable.
When an application is configured to use a specified DSCP value then the MPLS EXP, Dot1P bits
will be marked in accordance with the network or access egress policy as it applies to the logical
interface the packet will be egressing.
The DSCP value can be set per application. This setting will be forwarded to the egress IOM. The
egress IOM does not alter the coded DSCP value and marks the LSP-EXP and IEEE 802.1p
(Dot1P) bits according to the appropriate network or access QoS policy.
Table 23: DSCP/FC Marking
Protocol IPv4 IPv6
DSCP
Marking
Dot1P
Marking
Default
FC
IS-IS Yes NC
ARP Yes NC
LDP (T-LDP) Yes NC
MPLS (LSP ping,
etc.)
Yes Yes Yes NC
RSVP Yes Yes Yes NC
BGP Yes Yes Yes Yes NC
BFD Yes Yes Yes NC
RIP Yes Yes Yes Yes NC
MSDP Yes NC
PIM (SSM) Yes Yes Yes Yes NC
OSPF Yes Yes Yes Yes NC
SMTP Yes AF
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