Routing Instances Overview

You can create multiple instances of BGP, IS-IS, OSPF, PIM, RIP, and static routes by including statements at the [edit routing-instances routing-instance-name protocols] hierarchy level.

A routing instance is a collection of routing tables, interfaces, and routing protocol parameters. The set of interfaces belong to the routing tables, and the routing protocol parameters control the information in the routing tables.

You can configure four types of routing instances: forwarding, Layer 2 VPN (L2VPN), nonforwarding, and VPN routing and forwarding (VRF).

Each routing instance has a unique name and a corresponding IP unicast table. For example, if you configure a routing instance with the name my-instance, its corresponding IP unicast table will be my-instance.inet.0. All routes for my-instance are installed into my-instance.inet.0.

Configure global routing options and protocols for the master instance by including statements at the [edit protocols] and [edit routing-options] hierarchy levels. Routes are installed into the master routing instance inet.0 by default, unless a routing instance is specified.

Multiple instances of BGP, OSPF and RIP are used for Layer 3 VPN implementation. The multiple instances of BGP, OSPF and RIP keep routing information for different VPNs separate. The VRF instance advertises routes from the customer edge (CE) router to the provider edge (PE) router and advertises routes from the PE router to the CE router. Each VPN receives only routing information belonging to that VPN.

Forwarding instances are used to implement filter-based forwarding for Common Access Layer applications.

PIM instances are used to implement multicast over VPN applications.

Nonforwarding instances of IS-IS and OSPF can be used to separate a very large network
into smaller administrative entities. Instead of configuring a large number of filters, nonforwarding instances can be used to filter routes, thereby instantiating policy. Nonforwarding instances can be used to reduce the amount of routing information advertised throughout all components of a network. Routing information associated with a particular instance can be announced where required, instead of being advertised to the whole network.

L2VPN instances are used for Layer 2 VPN implementation.