2

Below is definition of Implicit Withdrawal by Wang et al. in the "Observation and Analysis of BGP Behavior under Stress" paper.

What I am not getting is how do I count implicit withdrawals? If for example, I have 4 BGP messages shown below that have same IP address and different AS-PATH attribute, how many implicit withdrawals do I have? Is it 3? Or 6? Do I look only consecutive messages when computing implicit withdrawal or I look at first message in respect to the rest, than second message in respect to the rest , and third message in respect to fourth?

If I look at consecutive messages the result would be 3, if I use second approach result is 6.

Please help, Jannine

TIME: 2001-9-16 00:00:06
TYPE: BGP4MP/BGP4MP_MESSAGE AFI_IP
FROM: 192.65.185.144
TO: 192.65.185.40
BGP PACKET TYPE: UPDATE
ORIGIN: IGP
AS_PATH: 6893 8938 1 297
NEXT_HOP: 192.65.185.144
ANNOUNCED: 192.152.102.0/24

TIME: 2001-9-16 00:00:18
TYPE: BGP4MP/BGP4MP_MESSAGE AFI_IP
FROM: 192.65.184.3
TO: 192.65.185.40
BGP PACKET TYPE: UPDATE
ORIGIN: IGP
AS_PATH: 513 10764 6509 297
NEXT_HOP: 192.65.185.9
ANNOUNCED: 192.152.102.0/24

TIME: 2001-9-16 00:00:36
TYPE: BGP4MP/BGP4MP_MESSAGE AFI_IP
FROM: 192.65.185.144
TO: 192.65.185.40
BGP PACKET TYPE: UPDATE
ORIGIN: IGP
AS_PATH: 6893 3561 209 297
NEXT_HOP: 192.65.185.144
ANNOUNCED: 192.152.102.0/24

TIME: 2001-9-16 00:00:44
TYPE: BGP4MP/BGP4MP_MESSAGE AFI_IP
FROM: 192.65.185.130
TO: 192.65.185.40
BGP PACKET TYPE: UPDATE
ORIGIN: IGP
AS_PATH: 559 8933 6509 297
NEXT_HOP: 192.65.185.130
ANNOUNCED: 192.152.102.0/24


Implicit Withdrawal Definition:If the sender announces a route
to a previously unreachable address, this is a new
announcement. If the sender announces a route to
a currently reachable address and the new route is
identical to the current route, this is a duplicate
announcement. Otherwise, the sender is replacing
the current route with a new route and this is an
implicit withdrawal.
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 10 '17 at 15:37
2

It would be 3 for the given messages. The first message contains an update and provided that you don't currently have a route for that prefix this would then be the first route that we installed. The subsequent messages contains information for the same prefix and therefore are implicit withdrawals.

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