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Administrative distance

  • 1.  Administrative distance

    Posted 03-20-2017 08:57

    Hi everyone,


    I just wanted to know why Juniper uses different AD values when compared to Cisco?

    I've tried to lookup RFC for AD numbering but it looks like it does not exist.


    Does anyone have a clue if AD numbering is regulated by some "standard", or is it up to vendor to choose the values?



  • 2.  RE: Administrative distance

    Posted 03-20-2017 09:24

    Hi !

    as far as I know there is NO standard on that

    Juniper calls it route preference and not the absolute number is important but the relative position to the preference of competing routing protocols


    in principle the sequence is quite similar between ciscdo and juniper ( NOT the abosulte value)

    the only main and important difference is EBGP ,on cisco it is considered better than any dynamic IGP, on juniper both IBGP and EBGP are considered less preferent than any IGP


    2017-03-20 17_22_02-JRE-12.a_C2_Routing_Fundamentals.jpg



  • 3.  RE: Administrative distance

    Posted 03-24-2017 04:12

    Hi pp490a,



    There is NO standard for AD.


    below is an excerpt from wiki


    Administrative distance (AD) is a number of arbitrary unit assigned to dynamic routes, static routes and directly-connected routes. The value is used by vendor-specific routers to rank routes from most preferred (low administrative distance value) to least preferred (high administrative distance value).When multiple paths to the same destination are available, the router uses the route with the lowest administrative distance and inserts the preferred route into its routing table. Router vendors typically design their routers to assign a default administrative distance to each kind of route that is used, however, this value can usually be set manually by a network administrator.



  • 4.  RE: Administrative distance

    Posted 03-26-2017 13:33

    Hi ,


    Here you can find the AD values in Juniper.



    Understanding Route Preference Values (Administrative Distance)