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    Understanding Route Preference Values (Administrative Distance)

    The Junos OS routing protocol process assigns a default preference value (also known as an administrative distance) to each route that the routing table receives. The default value depends on the source of the route. The preference value is a value from 0 through 4,294,967,295 (232 – 1), with a lower value indicating a more preferred route. Table 1 lists the default preference values.

    Table 1: Default Route Preference Values

    How Route Is Learned

    Default Preference

    Statement to Modify Default Preference

    Directly connected network

    0

    System routes

    4

    Static and Static LSPs

    5

    static

    Static LSPs

    6

    RSVP-signaled LSPs

    7

    RSVP preference as described in the MPLS Applications Feature Guide

    LDP-signaled LSPs

    9

    LDP preference, as described in the MPLS Applications Feature Guide

    OSPF internal route

    10

    OSPF preference

    IS-IS Level 1 internal route

    15

    IS-IS preference

    IS-IS Level 2 internal route

    18

    IS-IS preference

    Redirects

    30

    Kernel

    40

    SNMP

    50

    Router discovery

    55

    RIP

    100

    RIP preference

    RIPng

    100

    RIPng preference

    PIM

    105

    Multicast Protocols Feature Guide

    DVMRP

    110

    Multicast Protocols Feature Guide

    Aggregate

    130

    aggregate

    OSPF AS external routes

    150

    OSPF external-preference

    IS-IS Level 1 external route

    160

    IS-IS external-preference

    IS-IS Level 2 external route

    165

    IS-IS external-preference

    BGP

    170

    BGP preference, export, import

    MSDP

    175

    Multicast Protocols Feature Guide

    In general, the narrower the scope of the statement, the higher precedence its preference value is given, but the smaller the set of routes it affects. To modify the default preference value for routes learned by routing protocols, you generally apply routing policy when configuring the individual routing protocols. You also can modify some preferences with other configuration statements, which are indicated in the table.

    Modified: 2017-01-10