Two Default Routes!

[TheDukeofBaghdad]

hi Friends..

i need to install two default route between two routers the Main link will be the Tunnel (DMVPN) and the Redundant link will be through DDR (Dial-On-Demand Routing) (Phone Link).

both of them pointing to the same router.

the way i wanted to work is during normal operation Only the routes through the tunnel should be installed in the Routing Table, in case of a failure happen in the tunnel (The DDR Link will work Automatically within a minute) >> i wanted the Default Route pointing toward the Tunnel to removed and the default route pointing to the DDR installed instead.

what is the best way to install this route ? i worked on it yesterday in a live environment and try many things but nothing work perfectly as i wanted ?!!!

Here are some output:

R1#show run | include ip route
ip route 0.0.0.0 0.0.0.0 X.Y.120.125 20

R2#show run | include ip route
ip route 0.0.0.0 0.0.0.0 A.B.101.14

As soon as i found a good fix to this problem .. i will go again to this site and fix the problem.

your help is appreciated 

[John Blakley]

I'm confused about what you're wanting. You show two different routers with 2 different ADs. If you have the same route with different next hops and different ADs, the lower AD gets installed into the routing table. In your example, if they were on the same router, the 101.14 route would be in the table, and then when it goes down, the 120.125 route would get installed.

So, am I correct in that on R1, you would want:

ip route 0.0.0.0 0.0.0.0 x.y.120.125 20
ip route 0.0.0.0 0.0.0.0 x.y.101.14

and on R2, you would want:

ip route 0.0.0.0 0.0.0.0 x.y.120.125 20
ip route 0.0.0.0 0.0.0.0 x.y.101.14

If 101.14 went down, it would fail over to 120.125. Sorry if I misunderstood...

HTH,

John

[TheDukeofBaghdad]

hi John Blakley,

this will work on other situation when we have direct connection between R1-->R2 but here there is a ISP1 and ISP2 plus the internet.

This will clear things for you :

R1 --> ISP1 --> Internet --> ISP2 --> R2

lets say i install two route with the appropriate AD vales and than R1 lost his connection to ISP1, in this case DDR will work automatically and dial the other end and create the DDR link, and the route through the phone link will be installed in the routing table, but on the other end R2 still have his connection to ISP2 so the Default route will still pointing to the ISP2 which will make the routing not working between the two of them!

Thanks
Sensie

[Mukesh Kumar]

Hello TheDukeofBaghdad

As you are having two connections, one is through DMVPN tunnel and second is DDR phone link. You want to install 2 routes and if you want to give preference to tunnel route. In this case you have to assign lowest AD value to the tunnel route. If you tunnel interface goes down then tunnel route will be removed.

       But if your tunnel interface will not go down, there will be some other issue in the tunnel in that case tunnel route will not go down. So in this case to remove that route you can use SLA monitoring. By default static routes will be removed only if the interface towards which you have configured the static route will go down.

If you want to know any help regarding SLA monitoring then please tell me.

Regards,
Mukesh Kumar
Network Engineer
Spooster IT Services

[TheDukeofBaghdad]

hi Mukesh Jindal,

about the static route using lowest AD that will fix one end of the tunnel only, the side that lose connectivity to his ISP.

lets say:

R1 --> ISP1 --> Internet --> ISP2 --> R2

lets say i install two route with the appropriate AD vales and than R1 lost his connection to ISP1, in this case DDR will work automatically and dial the other end and create the DDR link, and the route through the phone link will be installed in the routing table, but on the other end R2 still have his connection to ISP2 so the Default route will still pointing to the ISP2 which will make the routing not working between the two of them!

i don't have information about SLA monitoring if you can give me a brief description that will be amazing ..

many thanks

Sensie 

[Bilal Nawaz · Accepted solution]

Hello Sensie,

I will attempt to show appropriate config for you.

#############################################

R1

conf t

!

#Configure IP SLA, x.x.x.x should be R2's primary IP, source interface via DMVPN Tunnel

ip sla 1

icmp-echo x.x.x.x source-interface T0

timeout 5000

frequency 10

#Configure IP SLA to become active

​ip sla schedule 1 start-time now life forever

#Configure the tracking of ip sla

track 1 ip sla 1 reachability

#Configure static route with tracking - Primary default route

ip route 0.0.0.0 0.0.0.0 p.p.p.p track 1

#Configure static route NO tracking (floating static) - Secondary DoD route

ip route 0.0.0.0 0.0.0.0 s.s.s.s 10

#########################################

R2

conf t

!

#Configure IP SLA, x.x.x.x should be R1's primary IP, source interface via Tunnel

ip sla 1

icmp-echo y.y.y.y source-interface T0

timeout 5000

frequency 10

#Configure IP SLA to become active

​ip sla schedule 1 start-time now life forever

#Configure the tracking of ip sla

track 1 ip sla 1 reachability

#Configure static route with tracking - Primary default route

ip route 0.0.0.0 0.0.0.0 p.p.p.p track 1

#Configure static route NO tracking (floating static) - Secondary DoD route

ip route 0.0.0.0 0.0.0.0 s.s.s.s 10

Hope this helps

Bilal - CCIE #45032

[Sarbjit-2014]

Hi,

Can you run HSRP on your network, this type of protocol would be ideal for your set up and provide you with the redundantcy needed.

[TheDukeofBaghdad]

hi Bilal,

Thanks for the description for Configuring the IP SLA .. sorry for taking long time to replay (i took the last week off).

I configure the routers with this configuration: (i didn't test it yet)

R1
ip sla 10
 icmp-echo 10.0.2.2 source-interface Tunnel0
 timeout 5000
 frequency 10
 exit
ip sla responder
ip sla schedule 10 start-time now life forever
track 10 rtr 10 reachability
 exit
no ip route 0.0.0.0 0.0.0.0 A.A.A.125
ip route 0.0.0.0 0.0.0.0 A.A.A.125 track 10
ip route 0.0.0.0 0.0.0.0 10.0.0.2 10

R2
ip sla 10
 icmp-echo 10.0.2.1 source-interface Tunnel0
 timeout 5000
 frequency 10
 exit
ip sla responder
ip sla schedule 10 start-time now life forever
track 10 rtr 10 reachability
 exit
no ip route 0.0.0.0 0.0.0.0 B.B.B.14
ip route 0.0.0.0 0.0.0.0 B.B.B.14 track 10
ip route 0.0.0.0 0.0.0.0 10.0.0.1 10
 

where A.A.A.125 is the ISP1 Connecting to R1, and B.B.B.14 is the ISP2 Connecting to R2.

R1--ISP1--Internet--ISP2--R2

R1--Phone link (DDR)--R2

The IP for the DDR is

R1: IP Address 10.0.0.1/30

R2: IP Address 10.0.0.2/30

[Wizard4777]

ip route 0.0.0.0 0.0.0.0 gw1

ip route 0.0.0.0 0.0.0.0 gw2

ip access-list 1 permit ip any any

route-map gw1

     match ip address 1

    match interface 1

route-map 2

     match ip address 1

     match interface 1

ip nat inside source route-map 1 interface 1 overload

ip nat inside source route-map 2 interface 2 overload

interface 1

    ip load-sharing per-destination

interface 2

    ip load-sharing per-destination