WAN Failover - IPSLA

[ctusa2003am]

Hi,

We have 2901 which has been in use for a while (before I came on board). They had a few different WAN links (Fiber, Cable Modem, ADSL etc.) so the configuration has been/is a bit complicated.

Now we have 2 lines:

1.      20 Mb Ethernet of Fiber  (GigabitEthernet0/0 10.20.0.18 ) – primary internet line. Have 30 usable IPs (69.24.45.128/27)

  2. Cable Modem  (Vlan13 71.9.153.78) (primarily for phone – have 5 static IPs – have 1 available i.e. .78)

I have attached the current config which will reflect some old configurations.

I need some help with using this Cable Modem line to be used as fail over if the main fiber internet access is dead.

I tried using IP SLA with Track 2 and put static route with cost 20 on cable modem but it did not fail over? So I created just static route May be I should reconfigure the cable modem interface i.e. get rid of the Vlan13 interface and use one of the physical interface (have plenty available).

Any help would be appreciated.

Thanks,

Ashok

[Philip D'Ath]

The "cablemodem" interface is in a separate VRF, and has no "ip sla" configured for it.  Tunnel20 is also configured to use the cablemodem vrf as its Internet connection.

By "failover" - what do you want to failover?  What should keep working if the main fibre fails?

[ctusa2003am]

Hi Philip,

Thanks for your reply. Yes, by fail over I meant, in case the main line (20Mb fiber) goes down, the default route should be the cable modem line. And when the fiber line is active again, then that should become the default route back.

The VRF was done earlier (I am sure they had good reason for that). Would I need that (VRF) to achieve what I want to do or something different/simpler?

Thanks,

AShok

[Support07]

Hello,

firstly you're tracking SLA2 but didn't attach to an ip route

could you try :

track 2 ip sla 2 reachability
 delay down 10 up 10
!
!
ip sla 2
 icmp-echo 8.8.8.8 source-interface GigabitEthernet0/0 !your primary internet access
ip sla schedule 2 life forever start-time now
!
!
ip route 8.8.8.8 255.255.255.255 10.20.0.17
ip route 0.0.0.0 0.0.0.0 gigabitEthernet0/0 10.20.0.17 track 2
ip route 0.0.0.0 0.0.0.0 71.9.153.73 20


could you tell me what's the interface GE0/1 ? Your second internet access ?

Vlan13 is your "Cable modem", this vlan is configured on interface FastEthernet0/0/3 who is down ?

Waiting your reply,

BR,

TkR07

[ctusa2003am]

Thanks BR,

I tried ip route 0.0.0.0 0.0.0.0 gigabitEthernet0/0 10.20.0.17 track 2

ip route 0.0.0.0 0.0.0.0 71.9.153.73 20

So did not have your first line (i.e.ip route 8.8.8.8 255.255.255.255 10.20.0.17)

So when I disconnected the Fiber line from Ge0/0) I lost the internet connection (sh ip route gave me the ' gateway of last resort is not set').

The reason I think because the vlan13 interface is 'down' down' - as you also observed.

So should I use the cable modem line as Vlan interface or just configure an available fast ethernet int for cable modem/71.x.x.78 and then try again ip route 0.0.0.0 0.0.0.0 71.9.153.73 20.

On your 2nd question ge0/1 is being used for all routable IPs provided by our Fiber ISP. That connects to a WAN switch, where I have our webserver and other devices using those public IPs.

I will look forward to your comments.

Thanks,

Ashok

[Support07]

Yes you can try to configure on FE interface,  and also make sure that the interface is up and that you can reach 71.x.x.73 from 71.x.x.78

Best regards,

TkR07_9393

[ctusa2003am]

Thanks - 

so what should be sequence. Should I delete/remove the vlan and vrf first and then assign the ip to one of the fe?

What would be the sequence of statements? Appreciate the help.

Thanks,

Ashok

[Support07]

You should remove the vlan and the vrf and try with physical interface

TkR07_9393

[ctusa2003am]

Hi again,

It is not letting me put the IP address Fe 0/0/0. Errors out since it is layer 2 int.

What is the solution?

Thanks,

Ashok

[Support07]

Hi,

Is it the first time that you are using cable modem ? Or before it was up ?

If it was on vlan 13 it's for one reason I think, maybe leave the vlan 13 and fe0/0/0. And just look why it is not up physically

Thanks

TkR07_9393

[ctusa2003am]

Hi,

Seems you are right. Probably this was the reason it was (Vlan13) there. Now that I have deleted the Vlan13 interface and also the VRF, guess have to redo this i.e. have to create vlan again.

Will do it on Monday and will report back. 

Would I need the vrf as well or just create the vlan , assign ip and subsequently put in the routing?

When you get a chance.

Thanks,

Ashok