I also see the load sharing. Keep in mind also that een though you have E2 routes, cost to the ASBR is not insignificant (show ip route X; look at forward metric), The presence of the FA does not guarantee that the route will be used. It just changes how OSPF router calculates the cost to the external route.
Last but not the least, FA *must* be known by OSPF and be installed in RIB by the OSPF process. If that's the case, the LSA is deemed invalid and will not be used for RIB calculation. -- Marko Milivojevic - CCIE #18427 (SP R&S) Senior CCIE Instructor / Managing Partner - IPexpert On Thu, Jun 20, 2013 at 7:02 AM, Tony Singh <[email protected]> wrote: > > well it seems you have either inter or intra area route to get to the asbr > hence reason it installs it, if you didn't then even though it receives it > from the abr it would not install the route....for this you'd prob use > suppress fa on the abr to get around it.... > > your trace is showing load sharing at both hops and without knowing your > topology/areas are any of the addresses in the trace i.e r1/r6 ASBR's > addresses? > > the forwarding address will be the highest ip address used by the asbr, > not necessarily in the data output > > feel free to correct my understanding > > -- > BR > > Tony > > Sent from my iPad > > On 20 Jun 2013, at 14:28, Elie Raad <[email protected]> wrote: > > > it is tony since the FA address is set. review the FA address > requirement for non-zero field. it is under the router ospf process on > router R6. > > > > > > ________________________________________ > > From: Tony Singh [[email protected]] > > Sent: Thursday, June 20, 2013 3:27 PM > > To: Elie Raad > > Cc: Marko Milivojevic; OSL Routing and Switching > > Subject: Re: [OSL | CCIE_RS] OSPF Q > > > > Elie is the 3.3.65.5 address in the global rib, if it isn't then the LSA > won't be considered for installation into the global rib from my testing... > > > > -- > > BR > > > > Tony > > > > Sent from my iPad > > > > On 20 Jun 2013, at 08:23, Elie Raad <[email protected]> wrote: > > > >> R4#sh ip ospf data external 5.5.5.5 > >> > >> OSPF Router with ID (4.4.4.4) (Process ID 1) > >> > >> Type-5 AS External Link States > >> > >> Routing Bit Set on this LSA > >> LS age: 767 > >> Options: (No TOS-capability, DC) > >> LS Type: AS External Link > >> Link State ID: 5.5.5.5 (External Network Number ) > >> Advertising Router: 1.1.1.1 > >> LS Seq Number: 80000002 > >> Checksum: 0xE0A6 > >> Length: 36 > >> Network Mask: /32 > >> Metric Type: 2 (Larger than any link state path) > >> TOS: 0 > >> Metric: 20 > >> Forward Address: 0.0.0.0 > >> External Route Tag: 0 > >> > >> Routing Bit Set on this LSA > >> LS age: 340 > >> Options: (No TOS-capability, DC) > >> LS Type: AS External Link > >> Link State ID: 5.5.5.5 (External Network Number ) > >> Advertising Router: 6.6.6.6 > >> LS Seq Number: 80000002 > >> Checksum: 0x2601 > >> Length: 36 > >> Network Mask: /32 > >> Metric Type: 2 (Larger than any link state path) > >> TOS: 0 > >> Metric: 20 > >> Forward Address: 3.3.65.5 > >> External Route Tag: 0 > >> traceroute 5.5.5.5 nu > >> 1 3.3.24.2 88 msec > >> 3.3.34.3 68 msec > >> 3.3.24.2 28 msec > >> 2 3.3.36.6 68 msec > >> 3.3.12.1 92 msec > >> 3.3.36.6 64 msec > >> The result is that OSPF is not using the FA address in this case even > it is set > >> > >> this is what i meant :) > >> > >> > >> R1 and R6 are ASBR > >> > >> > >> ________________________________ > >> From: Marko Milivojevic [[email protected]] > >> Sent: Wednesday, June 19, 2013 7:09 PM > >> To: Elie Raad > >> Cc: Saleh Batouq; OSL Routing and Switching > >> Subject: Re: [OSL | CCIE_RS] OSPF Q > >> > >> Well, you are mixing in two things here :-). The thread was originally > about the non-NSSA area. That's what I was answering about. > >> > >> In a case of the NSSA area, behavior is slightly different. NSSA ASBR > will set FA as the IP field to one of its own IP addresses advertised in > OSPF (preference given to Loopback). When the translating ABR creates Type > 5 LSA, this information will be preserved, allowing fo the optimal routing > to the ASBR. > >> > >> -- > >> Marko Milivojevic - CCIE #18427 (SP R&S) > >> Senior CCIE Instructor / Managing Partner - IPexpert > >> > >> > >> On Tue, Jun 18, 2013 at 10:55 PM, Elie Raad <[email protected]<mailto: > [email protected]>> wrote: > >> I mean in scenario where we have 2 Exits to O E1/E2 routes , OSPF will > choose to Replace the Advertising Router Attribute to the highest Router-id > Value between Both . in that case OSPF will route toward the one that is > matched inside the Advertising router value, this can cause sometimes > sub-optimal routing issue. > >> If the Forwarding Address value is set than OSPF will route toward the > Fa address field regardless of the one who did the T 7/5 Translation > ensuring Optimal path selection. > >> > >> what if this same route has been advertised but now with the > Advertising router field set and the Fa field Set. and there is no Type 7/5 > Translation since we Satisfied the below conditions for setting the FA to > non-zero. the question is what will OSPF choose as a next hope to get this > route installated in the RIB? > >> > >> > >> > >> > >> Regards, > >> > >> Elie Raad | Network and Systems Administrator > >> American University of Science and Technology > >> [email protected]<mailto:[email protected]> | Office: +961-1-218716 > Ext: 396 > >> Office Hours: Mon- Fri 9:00 am-16:00 pm UTC+02:00 > >> ________________________________ > >> From: Marko Milivojevic [[email protected]<mailto:[email protected] > >] > >> Sent: Tuesday, June 18, 2013 11:27 PM > >> To: Elie Raad > >> Cc: Saleh Batouq; OSL Routing and Switching > >> > >> Subject: Re: [OSL | CCIE_RS] OSPF Q > >> > >> What would OSPF use as next-hop where? > >> > >> -- > >> Marko Milivojevic - CCIE #18427 (SP R&S) > >> Senior CCIE Instructor / Managing Partner - IPexpert > >> > >> > >> On Tue, Jun 18, 2013 at 11:09 AM, Elie Raad <[email protected]<mailto: > [email protected]>> wrote: > >> What will ospf use as a next hop , the advertising router ip address or > the fa address > >> > >> Ignore any typos, sent from mobile device. > >> > >> On Jun 18, 2013, at 19:17, "Marko Milivojevic" <[email protected] > <mailto:[email protected]>> wrote: > >> > >> > >> Yes it is :-) > >> > >> On an ASBR that redistributes the route: > >> > >> 1) next-hop must be known by OSPF (enabled on the interface, or a more > specific OSPF route to it) > >> 2) exit interface for the next-hop must not be passive > >> 3) exit interface must be broadcast or non-broadcast > >> > >> If those are satisfied, redistributed route will have non-zero FA and > FA will be the next-hop of the redistributed route. > >> > >> -- > >> Marko Milivojevic - CCIE #18427 (SP R&S) > >> Senior CCIE Instructor / Managing Partner - IPexpert > >> > >> > >> On Mon, Jun 17, 2013 at 11:13 PM, Saleh Batouq <[email protected] > <mailto:[email protected]>> wrote: > >> I would also like to know!!! > >> > >> Best Regards, > >> > >> Saleh > >> > >> On Tue, Jun 18, 2013 at 9:22 AM, Elie Raad <[email protected]<mailto: > [email protected]>> wrote: > >> > >>> Hi Guys , > >>> > >>> is it possible to set the FA Address to non-zero for an O E1/E2 route? > >>> > >>> > >>> > >>> _______________________________________________ > >>> For more information regarding industry leading CCIE Lab training, > please > >>> visit www.ipexpert.com<http://www.ipexpert.com> > >>> > >>> Are you a CCNP or CCIE and looking for a job? Check out > >>> www.PlatinumPlacement.com<http://www.PlatinumPlacement.com> > >>> > >>> http://onlinestudylist.com/mailman/listinfo/ccie_rs > >>> > >> _______________________________________________ > >> For more information regarding industry leading CCIE Lab training, > please visit www.ipexpert.com<http://www.ipexpert.com> > >> > >> Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com<http://www.PlatinumPlacement.com> > >> > >> http://onlinestudylist.com/mailman/listinfo/ccie_rs > >> > >> > >> > >> _______________________________________________ > >> For more information regarding industry leading CCIE Lab training, > please visit www.ipexpert.com > >> > >> Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > >> > >> http://onlinestudylist.com/mailman/listinfo/ccie_rs > > > > > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
