H3C S9500 Series Operation Manual page 906

Operation Manual – MPLS L3VPN
H3C S9500 Series Routing Switches
Figure 1-5 Hierarchical MPLS L3VPN
1.1.5 Introduction to OSPF Multi-Instance
As one of the most popular IGP routing protocols, OSPF is used as an internal routing
protocol in many VPNs. Using OSPF on PE-CE links brings convenience to you
because in this case CE routers only need to support OSPF protocol, without the need
of supporting other protocols, and network administrator only have to know the OSPF
protocol. If you want to transform conventional OSPF backbone into MPLS L3VPN,
using OSPF between PE and CE can simplify this transform process.
Therefore IETF raised two new OSPF VPN extension drafts, to provide a complete
solution to SPPF problems in MPLS L3VPN application when OSPF is used as PE-CE
routing protocol. In this case, PE router must be able to run multiple OSPF instances,
each of which corresponds to one VPN instance, owns an individual interface, routing
table, and sends VPN routing information over MPLS network using BGP/OSPF
interaction.
If supporting OSPF multi-instance, one router can run multiple OSPF processes, which
can be bound to different VPN instances. In practice, you can create one OSPF
instance for each service type. OSPF multi-instance can fully isolate different services
in transmission, which can solve security problems with low cost to meet the needs of
customers. Generally, OSPF multi-instance is run on PEs; The CE running OSPF
multi-instance in the LAN is called multi-VPN-instance CE. At present, isolation of LAN
services implements by VLAN function of the switch. OSPF Multi-VPN-Instance CE
provides schemes of services isolation implemented on routers.
Chapter 1 MPLS L3VPN Configuration
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