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<p class="MsoNormal">Hello All,<o:p></o:p></p>
<p class="MsoNormal"> I notice that if BGP is directly connected, when BGP started, the bgp_start_locked() is called and using neigh_find2() to lookup the neighbor. In neigh_find2(), bird will loop iface_list and comparing the remote IP address with the
IP prefix of interface, checking whether is the subnet.<o:p></o:p></p>
<p class="MsoNormal">Now, I have a question that why not using route table to find the neighbor ? Since I have one case that make me have some confusion.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Test Case:<o:p></o:p></p>
<p class="MsoNormal" style="text-indent:9.75pt">DUT1 DUT2 DUT3<o:p></o:p></p>
<p class="MsoNormal"> lo interface 2000::1111/128 , interface3 3000:1::8/112 <-----------------------> interface4 3000:1::9/112, lo interface: 2000::2222/128<o:p></o:p></p>
<p class="MsoNormal"> interface1 2000::2/112 <------>interface2: 2000::1/112<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> suppose that the route table configuration are all reachable.<o:p></o:p></p>
<p class="MsoNormal"> 1. Anyone known the topology connection is normal or correct ?<o:p></o:p></p>
<p class="MsoNormal"> 2. If yes, when create BGP peer with loopback interface 2000::1111, remote IP 2000::2222.<o:p></o:p></p>
<p class="MsoNormal"> 3. BGP peer will use 2000::2222 to compare with interface prefix list on DUT2, find the neighbor interface2 with prefix 2000::1/112 [interface2 on DUT2], and consider as directly connected.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">BUT, actually, BGP peer TCP connection is not directly connected, and TCP connection don’t using interface2 on DUT2, but using interface3 on DUT2 to connect interface4 of DUT3.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best Regards,<o:p></o:p></p>
<p class="MsoNormal">Arvin Gan<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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