Dear all, I am trying to account for all implicitwithdrawal messages within a certain period of time looking at BGP updatemessages collected at rrc, Ripe.
Implicit Withdrawal Definition:If the sender announces a route to a currently reachable address and the newroute is identical to the current route, this is a duplicate announcement.Otherwise, the sender is replacing the current route with a new route and thisis an implicit withdrawal. (Wanget al. in the "Observation and Analysis of BGP iBehavior underStress") What I am trying to understand is how do Icount implicit withdrawals? If for example, I have 4 BGP messages shown belowthat have same IP address and different AS-PATH attribute, how many implicitwithdrawals do I have? Is it 3? If I look at consecutive messages that havesame IP address and different AS-PATH attribute the result would be 3 (Icompare first to the second, second to the third and third to the fourth –assuming they have same IP address and different AS-PATH I increment implicitwithdrawals). But I have come across a solution that takes a first message andcompares it to the rest of the messages. Than second message compares to therest of the messages. And lastly compares the third to the fourth. In this casenumber of implicit withdrawals is 6. Please advise. Thanks for your help. TIME: 2001-9-16 00:00:06 TYPE: BGP4MP/BGP4MP_MESSAGEAFI_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_MESSAGEAFI_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_MESSAGEAFI_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_MESSAGEAFI_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
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