
Route Distinguisher Type Field -  per [RFC4364]

(last updated 23 February 2006)

Route Distinguishers are used to create VPN-IPv4 addresses, as specified in
[RFC4364]. The RDs are structured so that every
service provider can administer its own "numbering space" (i.e., can make
its own assignments of RDs), without conflicting with the RD assignments
made by any other service provider. An RD consists of three fields: a
type field, an administrator field, and an assigned number field.
The value of the type field determines the lengths of the other two fields,
as well as the semantics of the administrator field. The administrator
field identifies an assigned number authority, and the assigned number
field contains a number which has been assigned, by the identified
authority, for a particular purpose.

The Route Distinguisher Type field is a two-byte field. Additional Route
Distinguisher Type field values with a high-order bit of 0 may be allocated
by IANA on a "First Come, First Served" basis. Values with a high-order bit
of 1 may be allocated by IANA based on "IETF consensus".

Type Value  Description                         Reference
----------  ----------------------------------- ---------
Type 0      Administrator field is a two-byte   [RFC4364]
            Autonomous System Number

Type 1      Administrator field is a four-byte  [RFC4364]
            IP Address

Type 2      Administrator field is a four-byte  [RFC4364]
            Autonomous System Number

References
----------
[RFC4364]   E. Rosen and Y.Rekhter, "BGP/MPLS IP VPNs", RFC 4364, February 2006.

(created 15 February 2005)

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