Specifications

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Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases
OL-1166-04
Chapter 10 Cisco IGX 8400 Series IP Service
IP Service—Functional Overview
QoS addresses two fundamental requirements for applications that run on a VPN: predictable
performance and policy implementation. Policies are used to assign resources to applications, project
groups, or servers in a prioritized way. The increasing volume of network traffic, along with
project-based requirements, results in the need for service providers to offer bandwidth control and to
align their network policies with business policies in a dynamic, flexible way.
VPNs based on Cisco MPLS technology scale to support many thousands of business-quality VPNs over
the same infrastructure. MPLS-based VPN services solve peer adjacency and scalability issues common
to large virtual circuit (VC) and IP tunnel topologies. Complex permanent virtual circuit/switched
virtual circuit (PVC/SVC) meshes are no longer needed, and providers can use new, sophisticated traffic
engineering methods to select predetermined paths and deliver IP QoS to premium business applications
and services.
MPLS VPNs over IP+ATM Backbones
Service providers can use MPLS to build intelligent IP VPNs across their existing ATM networks.
Because all routing decisions are precomputed into switching tables, MPLS both expedites IP
forwarding in large ATM networks at the provider edge, and makes it possible to apply rich Layer 3
services via Cisco IOS technologies in Layer 2 cores.
A service provider with an existing ATM core can deploy MPLS-enabled edge switches or routers
(LSRs) to enable the delivery of differentiated business IP services. The service provider needs only a
small number of VCs to interconnect provider edge switches or routers to deliver many secure VPNs.
Cisco IP+ATM solutions give ATM networks the ability to intelligently “see” IP application traffic as
distinct from ATM/Frame Relay traffic. By harnessing the attributes of both IP and ATM, service
providers can provision intranet or extranet VPNs. Cisco enables IP+ATM solutions with MPLS,
merging the application of Cisco IOS software with carrier-class ATM switches (see Figure 10-11).
Figure 10-11 MPLS-VPNs in Cisco IP+ATM Network
IP + ATM core
ATM, Frame Relay, and
leased line services
High-Speed Internet
access, business
quality IP-based
VPN services
VPN A
CE
VPN B
CE
Edge LSR
PE
Edge LSR
PE
Edge LSR
PE
25096
VPN B
CE
VPN A
CE