That is correct. There is BDR election and DR promotion. The reason for
that is "code reuse".
I remember when this was hashed and rehashed on this same forum back in '98
to everyone's utter bewilderment ;-)
-- Marko Milivojevic - CCIE #18427 (SP R&S) Senior CCIE Instructor / Managing Partner - iPexpert :: Free Video Training: http://youtube.com/iPexpertInc :: Social: http://twitter.com/@icemarkom | http://fb.me/ccie18427 :: iPexpert: http://www.ipexpert.com/Communities | +1-810-326-1444 On Mon, Feb 24, 2014 at 1:29 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote: > Now that everyone seems to have setled on an understanding of the > election process, I would like to restate that there is no DR election, > just BDR. > > If you follow the RFC, the only way to become DR is by having been > elected (or autonominated) BDR first. If I'm mistaken, I would like to > know. > > -Carlos > > Marko Milivojevic @ 23/02/2014 02:14 -0300 dixit: > > Yup, correct. Much more interesting is to observe what happens with the > > state machine on those spokes that were, form hub's perspective, DR and > BDR > > :-). Look at that one. > > > > And as Brian said - this is a broken setup, but it's an interesting to > > observe the process and understand WHY. And to add to Brian's list of > > places where this may be relevant today: PVLAN. > > > > -- > > Marko Milivojevic - CCIE #18427 (SP R&S) > > Senior CCIE Instructor / Managing Partner - iPexpert > > :: Free Video Training: http://youtube.com/iPexpertInc > > :: Social: http://twitter.com/@icemarkom | http://fb.me/ccie18427 > > :: iPexpert: http://www.ipexpert.com/Communities | +1-810-326-1444 > > > > > > > > On Sat, Feb 22, 2014 at 8:56 AM, Tony Singh <mothafungla_at_gmail.com> > wrote: > > > >> > >> Marko > >> > >> if we make the HUB priority 0 then each spoke would see the following in > >> the election debugs... > >> > >> Spoke 1 > >> *Mar 1 05:15:25.278: OSPF: Elect BDR 0.0.0.0 > >> *Mar 1 05:15:25.278: OSPF: Elect DR 2.2.2.2 > >> *Mar 1 05:15:25.278: DR: 2.2.2.2 (Id) BDR: none > >> > >> Spoke 2 > >> *Mar 1 05:15:26.774: OSPF: Elect BDR 0.0.0.0 > >> *Mar 1 05:15:26.774: OSPF: Elect DR 3.3.3.3 > >> *Mar 1 05:15:26.774: DR: 3.3.3.3 (Id) BDR: none > >> > >> where in fact the HUB see's > >> > >> R1#show ip ospf neighbor > >> > >> Neighbor ID Pri State Dead Time Address > Interface > >> 2.2.2.2 200 FULL/DR 00:00:33 172.168.18.2 > Serial1/0 > >> 3.3.3.3 100 2WAY/DROTHER 00:00:35 172.168.18.3 > Serial1/0 > >> > >> > >> so each spoke declares themselves as DR but the HUB elects one DR in > >> precedence of of priority/highest router-id > >> > >> the non DR/BDR spoke from HUBS perspective goes into a EXSTART and keeps > >> re-transmitting his DBD packet but stays in a DOWN state > >> > >> If the HUB remains as DR or BDR then we can get full LSA LSDB > replication > >> from each spoke in this design = NBMA ip ospf network broadcast > >> > >> Let me know if that's not right.. > >> > >> BR > >> > >> Tony > >> > >> > >> > >> On 22 February 2014 01:47, Marko Milivojevic <markom_at_ipexpert.com> > wrote: > >> > >>> Things do get a bit more tricky in hub and spoke configurations when > all > >>> routers don't see all the hellos. Try setting up hub-and-spoke making > sure > >>> hub is NOIT the DR. See what the result will be. Now, ignore for a > second > >>> the fact your routing will be broken, but observe DR/BDR status on the > 3 > >>> devices. It's really entertaining! > >>> > >>> -- > >>> Marko Milivojevic - CCIE #18427 (SP R&S) > >>> Senior CCIE Instructor / Managing Partner - iPexpert > >>> :: Free Video Training: http://youtube.com/iPexpertInc > >>> :: Social: http://twitter.com/@icemarkom | http://fb.me/ccie18427 > >>> :: iPexpert: http://www.ipexpert.com/Communities | +1-810-326-1444 > >>> > >>> > >>> > >>> On Fri, Feb 21, 2014 at 5:41 PM, vishal bhugra < > vishal.bhugra_at_gmail.com > >>>> wrote: > >>> > >>>> Thanks Marko and Brian > >>>> > >>>> Now I understood the complete election process > >>>> > >>>> > >>>> On Fri, Feb 21, 2014 at 4:28 PM, Marko Milivojevic < > markom_at_ipexpert.com > >>>> wrote: > >>>> > >>>>> > >>>>> During the WAIT state (dead-interval duration), all routers will be > >>>>> sending hellos with DR/BDR set to 0.0.0.0. However, all routers can > see > >>>>> each other's hellos and since noone is claiming DR/BDR they will hold > >>> the > >>>>> election - basically. each router will decide what's going to be the > >>>>> topology based on hellos they've observed. One that is at that time > >>>>> considered the best will claim DR and the second best will claim BDR. > >>>>> That's how they will populate the fields once they leave the WAIT > >>> state. > >>>>> > >>>>> -- > >>>>> Marko Milivojevic - CCIE #18427 (SP R&S) > >>>>> Senior CCIE Instructor / Managing Partner - iPexpert > >>>>> :: Free Video Training: http://youtube.com/iPexpertInc > >>>>> :: Social: http://twitter.com/@icemarkom | http://fb.me/ccie18427 > >>>>> :: iPexpert: http://www.ipexpert.com/Communities | +1-810-326-1444 > >>>>> > >>>>> > >>>>> > >>>>> On Fri, Feb 21, 2014 at 3:58 PM, vishal bhugra < > >>> vishal.bhugra_at_gmail.com>wrote: > >>>>> > >>>>>> Hello Brian > >>>>>> > >>>>>> Thanks for your kind answer. > >>>>>> > >>>>>> If I configure 5 routers on broadcast network, all with same > priority. > >>>>>> They > >>>>>> all are new in the segment and now the election start. Now my > >>> questions > >>>>>> are:- > >>>>>> > >>>>>> 1) Do all of them put their Router ID in DR field of Hello? and > >>> highest > >>>>>> RID > >>>>>> will become the DR and lower one will be the BDR ? > >>>>>> > >>>>>> > OR > >>>>>> > >>>>>> 2) Will some one put his router ID in BDR field ? and if yes how > will > >>> he > >>>>>> decide that it has to put the RID in BDR field of Hello packet and > >>> not > >>>>>> the > >>>>>> DR. > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> On Fri, Feb 21, 2014 at 2:28 PM, Brian McGahan <bmcgahan_at_ine.com> > >>> wrote: > >>>>>> > >>>>>>> In general the first router to join the segment becomes DR and the > >>>>>> second > >>>>>>> router to join becomes BDR. If DR fails the BDR is promoted to DR > >>> and > >>>>>> there > >>>>>>> is a new election for BDR. There are some odd corner cases where > >>> this > >>>>>> wont > >>>>>>> happen though. > >>>>>>> > >>>>>>> When the router joins the segment it listens for WAIT timer to > >>> expire. > >>>>>> If > >>>>>>> during this interval it receives a hello from another router on the > >>>>>>> segment, it will accept the DR information in the packet and start > >>> to > >>>>>> send > >>>>>>> hellos. If however no one is heard during WAIT, the router elects > >>>>>> itself DR > >>>>>>> and inserts this in its own hello. > >>>>>>> > >>>>>>> This mean that if for some reason communication is broken during > >>> WAIT > >>>>>>> interval, two routers can elect themselves as both DR, in which > case > >>>>>> there > >>>>>>> *will* be a preemptive election once they both hear each others > >>> hellos. > >>>>>>> > >>>>>>> For example this could happen if your OSPF DEAD/WAIT interval is > >>> lower > >>>>>>> than your STP Forward Delay, WAIT would expire before the router > can > >>>>>>> receive packets and it would elect itself as DR. > >>>>>>> > >>>>>>> This is not the normal case though. For more info see > >>>>>>> https://tools.ietf.org/html/rfc2328#page-75 > >>>>>>> > >>>>>>> > >>>>>>> Brian McGahan, 4 x CCIE #8593 (R&S/SP/SC/DC), CCDE #2013::13 > >>>>>>> bmcgahan_at_INE.com > >>>>>>> > >>>>>>> Internetwork Expert, Inc. > >>>>>>> http://www.INE.com <http://www.ine.com/> > >>>>>> > >>>>>>> > >>>>>>> On Feb 21, 2014, at 6:01 AM, "Carlos G Mendioroz" < > tron_at_huapi.ba.ar > >>>> > >>>>>>> wrote: > >>>>>>> > >>>>>>> I don't know where are you reading this, but I thought that there > is > >>>>>>> only BDR election process. Once you are BDR, then you can jump to > >>> DR if > >>>>>>> the current DR fails. > >>>>>>> > >>>>>>> So that is why, I guess. You don't opt, you have no choice :) > >>>>>>> -Carlos > >>>>>>> > >>>>>>> vishal bhugra @ 20/02/2014 20:28 -0300 dixit: > >>>>>>> > >>>>>>> Hello Experts > >>>>>>> > >>>>>>> > >>>>>>> While going through the DR and BDR election process. I gone through > >>> a > >>>>>> line > >>>>>>> > >>>>>>> wherein during the process of election the router will segregate > the > >>>>>> list > >>>>>>> > >>>>>>> of routers who have mentioned themselves as BDR and those who have > >>>>>>> > >>>>>>> mentioned themselves as DR. > >>>>>>> > >>>>>>> > >>>>>>> After segregation out of the list of BDR, the elected BDR will be > >>> with > >>>>>> the > >>>>>>> > >>>>>>> highest priority and if not then highest Router ID. > >>>>>>> > >>>>>>> > >>>>>>> Now my question is .. Why would a router will opt himself for BDR > >>> and > >>>>>> not > >>>>>>> > >>>>>>> for DR. Or we can say how a router will come to conclusion that it > >>> has > >>>>>> to > >>>>>>> > >>>>>>> go for be a BDR not the DR. > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> -- > >>>>>>> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina > >>>>>>> > >>>>>>> > >>>>>>> Blogs and organic groups at http://www.ccie.net > >>>>>>> > >>>>>>> > >>> _______________________________________________________________________ > >>>>>>> Subscription information may be found at: > >>>>>>> http://www.groupstudy.com/list/CCIELab.html > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>> > >>>>>> > >>>>>> -- > >>>>>> Thanks®ards > >>>>>> > >>>>>> Vishal > >>>>>> +91 8587900305 > >>>>>> > >>>>>> Best way to predict the future ..... is to create it > >>>>>> _______________________________________________ > >>>>>> Free CCIE R&S, Collaboration, Data Center, Wireless & Security > Videos > >>> :: > >>>>>> > >>>>>> iPexpert on YouTube: www.youtube.com/ipexpertinc > >>>>>> > >>>>> > >>>>> > >>>> > >>>> > >>>> -- > >>>> Thanks®ards > >>>> > >>>> Vishal > >>>> +91 8587900305 > >>>> > >>>> Best way to predict the future ..... is to create it > >>>> > >>> _______________________________________________ > >>> Free CCIE R&S, Collaboration, Data Center, Wireless & Security Videos > :: > >>> > >>> iPexpert on YouTube: www.youtube.com/ipexpertinc > > > > > > Blogs and organic groups at http://www.ccie.net > > > > _______________________________________________________________________ > > Subscription information may be found at: > > http://www.groupstudy.com/list/CCIELab.html > > > > > > > > > > > > > > > > -- > Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina Blogs and organic groups at http://www.ccie.netReceived on Mon Feb 24 2014 - 13:32:29 ART
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