upstream
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... ISP filtering
packets from its upstream providers, to get rid of packets with
"Martian" or other non-routed addresses ...
... ISP ensures) that the same
arrangements also apply to the ISP's upstream and peering links, if
ingress filtering ...
... ingress filtering is being used there -- or will get used, at some
point in the future; similarly with the upstream ISPs and peers.
...
... is not really that much different from the more typical "downstream"
or "upstream" ingress filtering.
...
... ingress filtering.
However, it's important to note that with mixed upstream/downstream
and peering links ...
... filter
out source addresses coming from an upstream link which should have
come over a peering link ...
... link (implying something like Strict RPF is used
towards the upstream) -- but this is a more complex topic and
considered out of scope; see Section 6.
...
... considered below.
The fourth and the fifth must be ensured in the upstream ISPs as
well, as described in Section 3.1.
...
... test. This argues in favor of either using a complete filter in the
upstream network or ensuring in the downstream network ...
... ISPs with BGP, to ensure that its prefix is carried upstream
to the major transit ISPs. Of necessity, this implies that the edge ...
... Martian
addresses. It can be applied in the upstream interfaces to reduce
the size of DoS attacks ...