From: Eric Leung (eric.lwc@gmail.com)
Date: Wed Sep 12 2007 - 09:47:37 ART
Hi Champika,
O, I got you. So I will put it like this:
1. Let R1, R2 and R4 as OSPF NSSA Area.
2. Enable HSRP on R2 and R4 interfaces connecting to the switches. With R2
interface being prefered and HSRP tracking their interfaces to R1.
3. Remove R3 and R5 from the OSPF routing domain. Just put a default route
at R3 and R5 to the standby HSRP.
4. Redistrubute the subnet behind R3 and R5 to OSPF.
5. Tune the cost between R1 and R4 so it is larger than that between R1 and
R2
So at normal situation, all outgoing traffic will go through R3 L2SW1 R2 R1
and the return path will be through R1 R2 L2SW1 and R3.
If the link between R1 and R2 dies, outgoing will be R3, L2SW1 L2SW2, R4, R1
and the return path will be R1 R4 L2SW2 L2SW1 R3. (thanks to HSRP).
If the link between R2 and R4 dies, outgoing traffic will be as normal.
If the link between R2 and L2SW1 dies, outgoing traffic will be R3 L2SW1 R4
R1. (thanks to HSRP).
2007/9/12, Champika G <693455@gmail.com>:
>
> Hi Eric
>
> It can go through R3->L2SW1->L2SW2->R4->R1 provided it comes back the
> same route. But this is not what is needed for this scenario.
>
> The link costs are all the same except for R4-L1SW2 link. THat cost is
> 3. Without that cost R1 will have equal cost routes to the vlan
> segments and will loadbalance between R1-R4 & R1-R2. This is not the
> required behavior.
> When all interface and devices are in an UP state the prefered return
> path is from R1-R2.
> This is actually a live scenario in Customer place and because the
> routers are running IOS FW services routing must be symetric.
> All links are 100mb ethernet.
> Therefore If R1-R2 link is not down traffic should come back that path
> irrespective of other link failures.
> All suggestions are welcome.
> CHeers.
>
>
> On 9/12/07, Champika G <693455@gmail.com> wrote:
> > The return path for (2) should be R1->R2->R4->L2SW2->L2SW1->R3 &
> > The return path for (3) should be R1->R4->R2>L2SW1->R3.
> >
> > Under normal circumstances R3 should route via R2-R1 link. So
> > essentially R2 is the primary router.
> >
> > On 9/12/07, Champika G <693455@gmail.com> wrote:
> > > THe drawing was not very clear.
> > > THe connections are;
> > >
> > > R1-R2 : p2p link
> > > R1-R4 : p2p link
> > > R2-R4 : p2p link
> > > R4-L2SW2 : L2 on SW
> > > R2-L2SW1 : L2 on SW
> > > L2SW2-R5 : L2 on SW
> > > L2SW1-L2SW2 : Trunk
> > > L2SW1-R3 : L2 on SW
> > > R3-R5 : p2p link
> > >
> > >
> > >
> > > On 9/12/07, Champika G <693455@gmail.com> wrote:
> > > > Hi Guys
> > > > Yes it works that way. I was trying a distribute list out in R2.
> Silly
> > > > me. Should have known better!!!!
> > > > Actually my original scenario is as below. I was trying to achieve
> > > > fault tolerent routing in R3 & R5.
> > > > Two new routers R4 & R5 are there seperated by a L2 switch. Switch
> to
> > > > switch is a trunk.
> > > > Area 1 is still a Totally stub area.
> > > > Conditions are;
> > > > (1) R3 is the HSRP active for ethernet segment vlans
> > > > (2) Incase of a link failure bet. R2-L2SW the traffic should be
> routed
> > > > R3->L2SW1->L2SW2->R4->R2->R1. The return path should be the reverse.
> > > > No asymetrical routing is allowed.
> > > > (3) If R1-R2 link is down traffic should be rerouted via
> > > > R3->L2SW1->R2->R4->R1. Return path should be the reverse. Again no
> > > > asymetric routing.
> > > > (4) R1 is the ABR.
> > > >
> > > > The question is if (2) or (3) happens the return path does not
> follow
> > > > the same outgoing path. How do i achieve that? Any thoughts
> > > >
> > > > ========(area 1)R4(area 1)==L2SW2==(area 1)R5-Vlans
> > >
> > || || ||
> > > > ||
> > > > ==(Area 0)R1(area 1)==(area 1)R2(area 1)==L2SW1==(area 1)R3-vlans
> > > >
> > > >
> > > > On 9/12/07, Champika G <693455@gmail.com> wrote:
> > > > > Dear All
> > > > >
> > > > > I have a situation where i want to stop the default route from
> > > > > propagating down to R3.
> > > > > R1 is the ABR and area 1 is a totally stub. R1 (ABR) injects a
> default
> > > > > to Area 1 and this default i can see in R3 as well.
> > > > > I want to stop R3 recieveing this default. ANy ideas how this can
> be
> > > > > done. I tried several methods but they did not work.
> > > > >
> > > > > OSPF
> > > > >
> > > > > ==(Area 0)R1(area 1)==(area 1)R2(area 1)==(area 1)R3
> > > > >
> > > > > Regards
> > > > > Champ
>
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