[j-nsp] Curly braces in AS-path

Phil Shafer phil at juniper.net
Tue Sep 10 13:03:27 EDT 2013

Vincent De Keyzer writes:
>What do the curly braces in the AS path mean? More generally, does someone
>know a document explaining how to interpret the output of "sh route prot

I don't see anything under "show route protocol bgp":


But under "show route advertising-protocol" you get decoder ring:


    AS path through which the route was learned. The letters at the
    end of the AS path indicate the path origin, providing an
    indication of the state of the route at the point at which the
    AS path originated:

    I - IGP.
    E - EGP.
    ? - Incomplete; typically, the AS path was aggregated.

    When AS path numbers are included in the route, the format is as follows:

    [ ] - Brackets enclose the local AS number associated with the
    AS path if configured on the router, or if AS path prepending
    is configured.
    { } - Braces enclose AS sets, which are groups of AS numbers
    in which the order does not matter. A set commonly results from
    route aggregation. The numbers in each AS set are displayed in
    ascending order.
    ( ) - Parentheses enclose a confederation.
    ( [ ] ) - Parentheses and brackets enclose a confederation set.

    Note: In Junos OS Release 10.3 and later, the AS path field
    displays an unrecognized attribute and associated hexadecimal
    value if BGP receives attribute 128 (attribute set) and you
    have not configured an independent domain in any routing instance.


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