Yes... OSPF with in area is link state but between area it behave like Distance Vector Protocol...
On Mon, Aug 17, 2009 at 12:44 PM, Steve Shaw <[email protected]> wrote: > To elaborate on Kim's answer: > > OSPF Area Border Routers act much like routers running a distance vector > protocol when it comes to type-3 LSAs from other OSPF areas. > > 1. An ABR will never re-advertise a learned type-3 LSA back into area 0 > (split-horizon) > 2. ABRs ignore LSAs created by other ABRs when learned through a > non-backbone area. > - Prevents an ABR from choosing a non-backbone path to area 0 > > > These rules can be overcome by a virtual link between ABRs in the event of > a backbone area partition. > > On Mon, Aug 17, 2009 at 2:06 PM, Kim Pedersen <[email protected]> wrote: > >> Hi, >> >> The only "split-horizon"- like thing i can come up with consists of >> ABR's not propagating any information learned from a LSA type 3 from >> another ABR through a non-backbone area, back into the backbone (area 0) >> again. In this manner i guess you could say "dont advertise back into >> area 0 something the area learned from area 0 in the first place". >> >> Dont know if thats what you are referring to. >> >> Sincerely, >> Kim Pedersen >> >> desmond Black wrote: >> > >> > Explanation given is to mean that there is no Split-Horizon Rule in >> OSPF. >> > >> > I dont want to confuse, but there is a Split-Horizon equivalent logic >> > of Distance-Vector R'tng Protocol in OSPF but cannot be termed >> > explicitly as Split-horizon. >> > In this logic if the Next-Hop of the Prefix is in the Area to which >> > the ABR is going to advertise the route [in form of LSA] OR the Prefix >> > itself is in that LSA...... do not advertise it into that Area. >> > >> > Desmond Black, >> > In Pursuit of CCIE!! >> > India >> > >> > ----- Original Message ----- >> > From: [email protected] >> > To: "desmond Black" >> > Cc: ��ս�� , [email protected] >> > Subject: Re: [OSL | CCIE_RS] How to disable OSPF splite horizon ? >> > Date: Mon, 17 Aug 2009 16:25:14 +0000 (GMT) >> > >> > can you give a bit more detail on the ospf split horizon pls... >> > >> > ----- Original Message ----- >> > From: desmond Black >> > Date: Monday, August 17, 2009 10:28 am >> > Subject: Re: [OSL | CCIE_RS] How to disable OSPF splite horizon ? >> > To: 邵战新 , [email protected] >> > >> > > Split-Horizon is needed in Distance vector Protocols since they >> > > do not >> > > have complete view of the topology and therefore to avoid loops >> > > tehy do >> > > not send back the routes originated by advertising peer back to >> > > it. RIP >> > > actually uses Split-horizon with Poison-Reverse just for making >> > > it sure. >> > > Since Protocols like OSPF & ISIS do have complete view of the >> > network >> > > they can make the decision themselves when the routes advertised >> > > by them >> > > will have had covered most "COST" and therefore would never get >> into >> > > Routing table. >> > > >> > > ----- Original Message ----- >> > > From: 邵战新 >> > > To: [email protected] >> > > Subject: [OSL | CCIE_RS] How to disable OSPF splite horizon ? >> > > Date: Mon, 17 Aug 2009 19:12:07 +0800 >> > > >> > > I got this open end question in ccie lab exam. Although I >> > > search it , >> > > I can't get answer. Who can know it ? Thanks >> > > >> > > --------------------------------------------------------------- >> > > ----- >> > > >> > > 搜索本应是快乐的，不是么? 快乐搜索，有问必应！微软隆重推出! >> > > 立即试用！ >> > > _______________________________________________ >> > > For more information regarding industry leading CCIE Lab training, >> > > please visit www.ipexpert.com >> > > >> > > >> > > >> > > >> > > Desmond Black, >> > > In Pursuit of CCIE!! >> > > India >> > > >> > > -- >> > > Be Yourself @ mail.com! >> > > Choose From 200+ Email Addresses >> > > Get a Free Account at www.mail.com! >> > > >> > > >> > >> > >> > >> > >> > >> > -- >> > Be Yourself @ mail.com >> > Choose From 200+ Email Addresses >> > Get a *Free* Account at www.mail.com <http://www.mail.com>! >> > ------------------------------------------------------------------------ >> > >> > _______________________________________________ >> > For more information regarding industry leading CCIE Lab training, >> please visit www.ipexpert.com >> > >> >> -- >> >> // Freedom Matters >> // Follow my progress on: http://kpjungle.wordpress.com >> >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> > > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > >
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
