Service Entities
Page 46 7750 SR OS Services Guide
Class-Based Forwarding
• Application of Class-Based Forwarding over RSVP LSPs on page 46
• Operation of Class-Based Forwarding over SDP LSPs on page 47
Application of Class-Based Forwarding over RSVP LSPs
Class based forwarding over RSVP LSPs allows a service packet to be forwarded over a specific
RSVP LSP, part of an SDP, based on its ingress determined forwarding class. The LSP selected
depends on the operational status and load-balancing algorithms used for ECMP and LAG
spraying.
Figure 9: Class-Based Forwarding over SDP LSPs
Figure 9 illustrates the use of class-based forwarding to direct packets of a service to specific
RSVP or static LSPs that are part of the same SDP based on the packets' forwarding class. The
forwarding class of the packet is the one assigned to the packet as a result of applying the ingress
QoS policy to the service SAP. The VLL service packets are all classified into the “
ef” forwarding
class and those that are destined to PE2 are forwarded over LSP1. Multicast and broadcast are
classified into the “
be” class and are forwarded over LSP2.
This feature allows service providers to dedicate specific LSPs with a determined level of traffic
engineering and protection to select service packets. For example, packets of a VoIP service are
assigned the “
ef” class to expedite their forwarding but are also sent over carefully traffic-
engineered and FRR-protected LSP paths across the service provider network.
IP/MPLS
CE 2
[64.47.30.2/32]
CE 4
[64.47.31.2/32]
CE 1
[64.47.30.1/32]
CE 3
[64.47.31.1/32]
Ethernet/LAN
SAP 1/1/1:1000
Ethernet/VLAN
SAP 3/1/1:1001
ATM SAP
2/1/1:0/100
FR SAP
1/1/1:100
PE 1
PE 2
7x50
7x50
OSSG106
SDP
LSP1 (EF)
LSP2 (BE)
VLL
VPLS
VLL
VPLS
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