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Re: Order of ASes in the BGP Path
- From: Paul Jakma
- Date: Mon Aug 29 14:52:12 2005
On Mon, 29 Aug 2005, Abhishek Verma wrote:
Legend: {} denotes the sequence, while [] denotes the set
Path {1 2} [3 4] {5}
Would somebody mind if this was represented as {1 2 5} [3 4] ?
Yes, they are different paths. You are allowed to merge adjacent
sequences, eg:
{1 2} {5} [3 4]
the two sequences can be merged, to give:
{1 2 5} [3 4]
You can *not* merge AS_SET's, as the current BGP specs imply an
AS_SET has a fixed path-length, hence you should NOT merge the sets
in:
{1 2} [3 4] [5 6]
into:
{1 2} [3 4 5 6]
as the former path has a length of 3, the latter a length of just 2 -
merging sets could change their meaning. Note though that you're not
at all likely to see such paths with BGP speakers implementing the
RFC / draft-ietf-idr-bgp-26.txt draft.
regards,
--
Paul Jakma paul@clubi.ie paul@jakma.org Key ID: 64A2FF6A
Fortune:
The best way to make a fire with two sticks is to make sure one of them
is a match.
-- Will Rogers
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