Dual Internet in a active passive setup.

[Mike Buyarski]

I am trying to setup a config where i can have both my wired (primary) and Cellular (backup) connection in a active/passive setup to where is the wired connection drops it will swing over to the cellular then back to wired when wired is back up. 

right now what i have works to a point, it simply does NOT swing back to the wired connection when the wired connection comes back up. I of course want it on the wired as much as i can to not use to much data on the cellular data.

Notes:

cisco 892fsp IOS ver 15.6(3)M5

vlan 15 is for the cellular connection.

gig8 is the wired connection.

/////////config////////////

ip nat inside source route-map CELLNAT interface Vlan15 overload

ip nat inside source route-map WIREDNAT interface GigabitEthernet8 overload

.........

ip route 0.0.0.0 0.0.0.0 "Wired Gateway" track 1

ip route 0.0.0.0 0.0.0.0 Vlan15 250

.......

ip sla 1

icmp-echo 8.8.8.8 source-interface GigabitEthernet8

threshold 15

timeout 2000

frequency 3

ip sla schedule 1 life forever start-time now

.......

route-map WIREDNAT permit 11

match ip address 102

match interface GigabitEthernet8

!

route-map CELLNAT permit 10

match ip address 102

match interface Vlan15

.........

access-list 102 permit ip "internal ip 1" any

access-list 102 permit ip "internal ip 2" any

access-list 102 permit ip "internal ip 3" any

[Seb Rupik · Accepted solution]

Hi there,

From the config you have supplied you are missing a track statement. You should have:

!
track 1 ip sla 1 reachability
!

Can you supply the output of sh track and sh ip route, for each of the follow states:

ISP1 up, ISP2 up

ISP1 down, ISP2 up

ISP1 back up, ISP2 up

cheers,

Seb.

[Mike Buyarski]

OK i did update the config, but we will not know until the main connection drops out. i will do this config to a few of them i have to maybe increase the number this is configured on. 

[Seb Rupik]

If the track statement was missing, its inclusion should fix your problem.

[Mike Buyarski]

Based on recent events adding that line has allowed it to work as we wanted. 

[paul driver]

Hello

---

@Mike Buyarski wrote:

right now what i have works to a point, it simply does NOT swing back to the wired connection when the wired connection comes back up. I of course want it on the wired as much as i can to not use to much data on the cellular data.

.......

ip sla 1

icmp-echo 8.8.8.8 source-interface GigabitEthernet8

---

Possible the reason is you ip sla address your monitoring is still reachable after failure , try changing this to a more specific address to gig8 which can reach like its next-hop interface ip address

[Mike Buyarski]

I choose 8.8.8.8 since that is the one what seems to work best for us. i can't use the gateway since that most of the time is accessible during an outage. usually i can't find a further upstream from that connection IP i can use.