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<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Hi Santosh,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"> Yes, I have tried /31 prefix. Sessions do come up in /31 prefix.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"> I am using version 7.2. I have a loopback interface with multiple /32 prefix IPs assigned. This loopback is borrowed by an unnumbered OSPF interface. Two node, directly connected
single link ospf topology, as give below. When only one IP is present in the loopback interface, sessions comes up. If more than one Ip is added to the loopback interface, ospf session keep getting flap/reset.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Difference I see between /32 and / <1-31> Prefix is that, in hello packet network mask is set to 0 in case of /32. Upon receiving Hello for the other IP which is different from
current adjacency ip, adjacency will be re-inited.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">static int
<b>ospf_make_hello</b>(struct ospf_interface *oi, struct stream *s)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> if (!(CHECK_FLAG(oi->connected->flags, ZEBRA_IFA_UNNUMBERED) && oi->type == OSPF_IFTYPE_POINTOPOINT)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> && oi->type != OSPF_IFTYPE_VIRTUALLINK)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> masklen2ip(oi->address->prefixlen, &mask);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> else<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> memset((char *)&mask, 0, sizeof(struct in_addr));
<span style="background:yellow;mso-highlight:yellow"><<<<</span></span><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">DUT1#<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">Sudo config loopback add Loopback0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">sudo config interface ip add Loopback0 10.0.0.1/32;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">sudo config interface ip add Loopback0 11.1.1.1/32;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">config interface ip unnumbered add Ethernet16 Loopback0
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">interface Ethernet16<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">ip ospf network point-to-point<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">ip ospf area 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">router ospf<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">ospf router-id 1.1.1.1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">DUT2#<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">Sudo config loopback add Loopback0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">sudo config interface ip add Loopback0 10.0.0.2/32;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">sudo config interface ip add Loopback0 11.1.1.2/32;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">config interface ip unnumbered add Ethernet16 Loopback0
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">interface Ethernet16<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">ip ospf network point-to-point<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">ip ospf area 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">router ospf<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";mso-fareast-language:EN-US">ospf router-id 2.2.2.2<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Regards<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Naveen<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="color:black">From: </span></b><span style="color:black">Santosh P K <sapk@vmware.com><br>
<b>Date: </b>Tuesday, 7 January 2020 at 9:54 PM<br>
<b>To: </b>Naveen K Suvarna <naveen.suvarna@broadcom.com>, "dev@lists.frrouting.org" <dev@lists.frrouting.org><br>
<b>Subject: </b>Re: OSPF neighbour-ship on multi-ip P2P interface<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman",serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Naveeen,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> Did you test with /31 prefix configured on interface and did that work too? Could you also let me know which version of FRR you are using?
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Thanks</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Santosh P K </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="color:black">From: </span></b><span style="color:black">Naveen K Suvarna <naveen.suvarna@broadcom.com><br>
<b>Date: </b>Tuesday, 7 January 2020 at 2:33 PM<br>
<b>To: </b>"dev@lists.frrouting.org" <dev@lists.frrouting.org><br>
<b>Subject: </b>OSPF neighbour-ship on multi-ip P2P interface</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Hi,</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"> Does FRR OSPF support neighborship on an P2P interface with Multiple Interface IP addresses? I am using multiple 32bit host ip address on same interface.</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"> When I try to establish ospf neighborship on an P2P interface with multiple IP addresses assigned, OSPF neighborship keeps resetting due to, receival of interleaving hello of 1<sup>st</sup>
or 2<sup>nd</sup> ip-address. Is there any way to avoid this and bring up sessions on the Interface.</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"> Above thing works good if the Interface IP addresses are assigned < 32 bit subnet mask (for example, 10.0.0.1/24 instead of 10.0.0.1/32).
</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Regards</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Naveen</span><o:p></o:p></p>
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