Thanks Marko and Brian Now I understood the complete election process
On Fri, Feb 21, 2014 at 4:28 PM, Marko Milivojevic <[email protected]>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 <[email protected]>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 <[email protected]> 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 >> > [email protected] >> > >> > Internetwork Expert, Inc. >> > http://www.INE.com <http://www.ine.com/> >> >> > >> > On Feb 21, 2014, at 6:01 AM, "Carlos G Mendioroz" <[email protected]> >> > 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 <[email protected]> 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
