LTE to LAN Alternation

[abc1235]

Hallo,

I have an LTE router that I would like to use LAN connection whenever I plug in the LAN cable and automatically disconnect the LTE connection. Could anyone kindly let me know how to do this? I can only think of an if...else statement but I don't know how I can integrate it into the router's configs.

I will appreciate your help.

Regards,

Joy

[Flavio Miranda · Accepted solution]

Hi

 Maybe this can be more simple. For example, you could install two static route on the router . One route  pointing to LTE gateway and another one pointing to LAN gateway. Then, let the static route to the LTE gateway with higher AD (Administrative Distance). Higher AD means less preferable.

Then, you let the route to LAN gateway with lower AD.  When the cable is off, although LTE have higher AD, packets will be sent out LTE considering it is the only option.

When you plug the LAN cable in, there will be two option and the LAN network will be prefarable as it has Lower AD.

[abc1235]

Hi @Flavio Miranda Thanks for your response. The following is my configuration after your suggestion:

interface GigabitEthernet0/1/7
description UPLINK-MPLS
switchport trunk native vlan 200
switchport trunk allowed vlan 297-300
switchport mode trunk
bandwidth 1000000
spanning-tree portfast trunk
service-policy output WAN
ip dhcp snooping trust

***truncated***

ip route vrf INTERNET 0.0.0.0 0.0.0.0 Cellular0/2/0 10

[JimWicks]

GigabitEthernet0/1/7 is not a routed interface so even when it comes up it will not affect your routing table.  Your next-hop will need to be a L3 SVI within the Internet VRF, looking at the trunk config that is either VLAN200 or VLAN297 thru VLAN300...........................something like

ip route vrf INTERNET 0.0.0.0 0.0.0.0 <next-hop-l3-address> 3

[Flavio Miranda]

Dont point to the interface, use IP address gateway as I told. And, try to change Administrative Distance of one route, this way, if you see in the situation where both interface are up, the router will prefer what you want to.

[abc1235]

@JimWicks and @Flavio Miranda Thanks for the additional info. Maybe a very basic question, but then what port will the LAN cable be connected from the ISR1116 router to the next hop switch? I thought I would have the gi1/0/7 used as the uplink port but as you say, it is not a routed port (with the change below will it be one?).

interface GigabitEthernet0/1/7
description UPLINK-MPLS
switchport trunk allowed vlan 297-300
switchport mode trunk
service-policy output WAN
ip dhcp snooping trust

Thanks again. 

[Flavio Miranda]

You dont need to worry about the physical port, you can use the same you use today.  When you point to gateway IP address, this is Layer 3 decision and not Layer 2.

I am assuming you use the same port today to connect to one next hop switch and another, right?  Just keep this way.

[abc1235]

Hi @Flavio Miranda. Oh now I get it. So, I can connect the router on port gi0/1/7 to the next hope switch and then configure it with the

ip route vrf INTERNET 0.0.0.0 0.0.0.0 <next hop> 3

then this should work. I will give this a try tomorrow. Thanks so much

[Flavio Miranda]

You got it. 

[abc1235]

Hallo @Flavio Miranda and @JimWicks Thanks again for the informative answers. It is working now