Ip Tunnel Routing Table; Shared Ip Interfaces - Juniper IGP - CONFIGURATION GUIDE V11.1.X Configuration Manual

JUNOSe 11.0.x IP, IPv6, and IGP Configuration Guide

IP Tunnel Routing Table

The IP tunnel routing tables include IPv4 routes that point only to tunnels, such as
MPLS tunnels. The tunnel routing table is not used for forwarding. Instead, protocols
resolve next hops by looking up the routes that point to tunnels. The routes in the
tunnel routing table cannot be redistributed. See JUNOSe BGP and MPLS Configuration
Guide for more information.

Shared IP Interfaces

You can create multiple shared IP interfaces over the same layer 2 logical
interface for example, atm 5/3.101 enabling more than one IP interface to share
the same logical resources. You can configure one or more shared IP interfaces. Data
sent over shared interfaces uses the same layer 2 interface. You can configure shared
interfaces as you would unshared IP interfaces. Each shared interface has its own
statistics.
Some layer 2 interfaces require a primary IP interface to negotiate certain IP
parameters for example, IPCP for PPP, ARP for Ethernet, and Inverse ARP for
Frame Relay. If you do not configure a primary IP interface in such cases, the layer
2 interface cannot become operationally up.
A primary IP interface is the default interface for receiving data that arrives on the
layer 2 interface. If you configure shared IP interfaces for the same layer 2 interface
as your primary IP interface, by default data received on the layer 2 interface is
received on the virtual router corresponding to the primary IP interface. A primary
IP interface and all of its shared IP interfaces have the same interface location. You
can configure a shared IP interface to receive data on the same layer 2 interface as
a primary IP interface. You can delete primary and shared IP interfaces independently
of each other.
You can create a primary IP interface as you do any other IP interface, as shown in
the following example:
You do not have to configure a primary IP interface if you do not need one as
described above. In the absence of a primary interface, you can still configure shared
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Shared IP Interfaces
Setting the hold-down timer to zero (0) distributes an update after each change
to the routing table, which can degrade SRP performance.
Example
host1(config)#forwarding-table route-holddown 15
Use the no version to set the hold-down timer to the default value, 3 seconds.
See forwarding-table route-holddown
host1(config)#virtual-router vr-a:vrf-2
host1:vr-a:vrf-2:(config)#interface atm 5/3.101
host1:vr-a:vrf-2:(config-if)#ip address 10.1.1.1 255.255.255.255
host1:vr-a:vrf-2:(config-if)#exit