2 router and 2 isp via iBGP failover setup help required

[doncarei2]

The above diagram shows the setup of my network.

Router model : 2911 with ios 15.1 (both)

R1 is my main router , all incoming and outgoing traffic will be handled by R1.

As for R2, if and only if ISP A is down and unable to connect to the internet, then R2 will take over the job. But once ISP A is back online, R2 will hand over the job back to R1.

My question in which approach to setup this failover is a better way?  

I am also curious if ip sla work for this case?

[Dragan Ilic]

HSRP (or VRRP) with help of IP SLA will do this job for you...i don't see any need for iBGP here btw if you already don't have BGP with your providers...

That's my personal opinion...

BR,

Dragan

[doncarei2]

the isp A and B are aggrating our ASN.

[Dragan Ilic]

OK then iBGP makes sense...you have plenty options for this to make it work as I already mentioned some of them.

BR,

Dragan

[doncarei2]

Router 1:

interface Serial0/0/0.1 ip routing  ! Points at the interface that needs to be Prioritized
interface FastEthernet0/0
 description interface to LAN
 ip address x.x.x.x 255.255.255.0
 standby 1 ip <Gateway>                 ! Virtual IP     (IP Virtual)
 standby 1 priority 105                 ! Higher Priority = Primary Router
 standby 1 preempt                      ! Enables the router with the highest priority to
                                        ! immediately become the active router
 standby 1 track 1                      ! WAN SUBINTERFACE
!
 Router bgp <ASN>
  network <Gateway> mask 255.255.255.0  ! Broadcasts Gateway out the WAN through BGP

Router 2:

track 1 interface Serial0/0/0.1 ip routing  ! Points at the interface that needs to be
                                            ! Prioritized
interface FastEthernet0/0
 description interface to LAN
 ip address x.x.x.x 255.255.255.0
 standby 1 ip <Gateway>                 ! Virtual IP
 standby 1 priority 100                 ! Lower Priority = Backup Router
 standby 1 preempt                      ! Enables the router with the highest priority to
                                        ! immediately become the active router
 standby 1 track 1                      ! WAN SUBINTERFACE
!
 Router bgp <ASN>
  network <Gateway> mask 255.255.255.0  ! Broadcasts Gateway out the WAN through BGP

By doing the following to my 2 router is that enough? to have the automatic failover if ISP A went down routing will go thur R2?

when ISP A is up routing will go back to R1

[Dragan Ilic]

For HSRP part you need to decrement priority in case link to ISP goes down (ie track goes down...)

I think you need better track config - use IP SLA with ICMP echo (ping) for testing if link is live.

BR,

Dragan

[doncarei2]

but isnt the R2 has lower priority than R1 already? so it should go down when R1 is up

[Dragan Ilic]

Yea I checked on cisco.com - if you stay with your config by default its going to decrement priority by 10 so its gonna a work 

For IP SLA I think ping is better option...

BR,

Dragan

[doncarei2]

is there any source or example for this setup, i am new to ip sla setup

[Bilal Nawaz]

Your standby 1 track 1 command will help you decrement the priority of HSRP in the event of failure. The priority set on your router is fine, default decrement value for priority is 10. So....

ip sla 1

#### We want to make sure full internet connectivity by ping 8.8.8.8 from WAN below. ####

icmp-echo 8.8.8.8 source-interface <your WAN interface>

frequency 10

timeout 1000

!

ip sla schedule 1 forever start-time now

!

track 1 ip sla 1 reachability

The rest of the config you already have complete.

Hope this helps

[doncarei2]

pardon for my noobness, does this apply to R1 only or both the router?

[Bilal Nawaz]

Only applies to R1 right? Why? because that is your main link attached. If that fails you don't need any sla to track router 2's link since its being used.

When R1's link fails you want it to decrement HSRP priority. R2 will never need to decrement its priority, since depending on R1's internet reachability status out to 8.8.8.8 will either be active or standby.

Hope this explains why.

[doncarei2]

if that the case, will R2 go down when R1 is up again? 

[Bilal Nawaz]

When R1 comes back and has reachability, then R1 will become the HSRP active gateway and will forward traffic. R2 "won't go down" - nothing will happen with R2 apart from, will become HSRP secondary instead of primary.

So when R1 comes back R1 will be used, when R1 fails then R2 will be used.

Please read this for reference:

http://www.cisco.com/c/en/us/support/docs/ip/hot-standby-router-protocol-hsrp/9234-hsrpguidetoc.html