<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3848" style="margin-bottom: 12pt; line-height: 14.65pt;"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3850" class="" style="color: rgb(34, 34, 34);">Dear all,</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3854" style="margin-bottom: 12pt; line-height: 14.65pt;"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3856" class="" style="color: rgb(34, 34, 34);">I am trying to account for all implicit withdrawal messages within a certain period of time looking at BGP update messages collected at rrc, Ripe. </span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3860" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3862" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">Implicit Withdrawal Definition: 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. (</span><span id="yiv9739217820yui_3_16_0_1_1444557033460_3864" class="" style="color: rgb(34, 34, 34); background: white;">Wang et al. in the "Observation and Analysis of BGP iBehavior under Stress"</span><span id="yiv9739217820yui_3_16_0_1_1444557033460_3866" class="" style="color: rgb(34, 34, 34);">)</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3870" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3872" class="" style="color: rgb(34, 34, 34);"> </span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3874" style="margin-bottom: 12pt; line-height: 14.65pt;"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3876" class="" style="color: rgb(34, 34, 34);">What I am trying to understand 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? If I look at consecutive messages that have same IP address and different AS-PATH attribute the result would be 3 (I compare 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 implicit withdrawals). But I have come across a solution that takes a first message and compares it to the rest of the messages. Than second message compares to the rest of the messages. And lastly compares the third to the fourth. In this case number of implicit withdrawals is 6. Please advise.</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3880" style="margin-bottom: 12pt; line-height: 14.65pt;"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3882" class="" style="color: rgb(34, 34, 34);">Thanks for your help.</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3886" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3888" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TIME: 2001-9-16 00:00:06</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3892" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3894" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TYPE: BGP4MP/BGP4MP_MESSAGE AFI_IP</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3898" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3900" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">FROM: 192.65.185.144</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3904" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3906" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TO: 192.65.185.40</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3910" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3912" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">BGP PACKET TYPE: UPDATE</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3916" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3918" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">ORIGIN: IGP</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3922" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3924" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">AS_PATH: 6893 8938 1 297</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3928" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3930" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">NEXT_HOP: 192.65.185.144</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3934" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3936" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">ANNOUNCED: 192.152.102.0/24</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3940" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3942" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;"> </span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3944" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3946" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TIME: 2001-9-16 00:00:18</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3950" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3952" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TYPE: BGP4MP/BGP4MP_MESSAGE AFI_IP</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3956" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3958" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">FROM: 192.65.184.3</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3962" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3964" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TO: 192.65.185.40</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3968" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3970" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">BGP PACKET TYPE: UPDATE</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3974" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3976" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">ORIGIN: IGP</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3980" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3982" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">AS_PATH: 513 10764 6509 297</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3986" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3988" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">NEXT_HOP: 192.65.185.9</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3992" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_3994" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">ANNOUNCED: 192.152.102.0/24</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_3998" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4000" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;"> </span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4002" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4004" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TIME: 2001-9-16 00:00:36</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4008" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4010" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TYPE: BGP4MP/BGP4MP_MESSAGE AFI_IP</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4014" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4016" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">FROM: 192.65.185.144</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4020" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4022" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TO: 192.65.185.40</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4026" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4028" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">BGP PACKET TYPE: UPDATE</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4032" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4034" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">ORIGIN: IGP</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4038" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4040" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">AS_PATH: 6893 3561 209 297</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4044" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4046" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">NEXT_HOP: 192.65.185.144</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4050" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4052" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">ANNOUNCED: 192.152.102.0/24</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4056" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4058" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;"> </span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4060" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4062" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TIME: 2001-9-16 00:00:44</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4066" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4068" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TYPE: BGP4MP/BGP4MP_MESSAGE AFI_IP</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4072" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4074" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">FROM: 192.65.185.130</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4078" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4080" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">TO: 192.65.185.40</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4084" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4086" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">BGP PACKET TYPE: UPDATE</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4090" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4092" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">ORIGIN: IGP</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4096" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4098" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">AS_PATH: 559 8933 6509 297</span></div><div class="" id="yiv9739217820yui_3_16_0_1_1444557033460_4102" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4104" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">NEXT_HOP: 192.65.185.130</span></div><div class="" dir="ltr" id="yiv9739217820yui_3_16_0_1_1444557033460_4108" style="margin-bottom: 0.0001pt; background: rgb(238, 238, 238);"><span id="yiv9739217820yui_3_16_0_1_1444557033460_4110" class="" style="color: rgb(34, 34, 34); border: 1pt none windowtext; padding: 0in;">ANNOUNCED: 192.152.102.0/24</span></div></div></body></html>