For origin validation we have a special
case
involving as0 and this is described in
RFC 6480.
It's known as disavowal of routing
origination
es0 has been reserved for network
operators and other entities to identify
non-routed networks and this means
a raw with our subject of as0 is an
attestation
by the holder of a prefix that the
prefix described in the raw
and any more specific should not be used
in a routing context
any prefixes with a row indicating a 0
as the origin as
need to be dropped if these prefixes
appear with any other origin
the rows will be invalid achieving this
goal
so where would we use it well es0 raw
could be used for internal use of a
prefix that should not
appear in the global bgp table
it could be used by internet exchange
points because internet exchange
point lan must never appear in the
global bgp table either
it will be visible in the member's
routing table
but would never appear visible on the
global default free zone
private address space perhaps for ipv4
and non-global unicast address space for
ipv6
other possibility could be unassigned
address space
and at the time of this recording this
was under active discussion in the
various
regional internet registry policy forum
ipv4 and ipv6 address resources which
should not appear in the global bgp
table could also be signed
with the as0 raw for example the special
use address space described in RFC 6890.
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