Adding route alternative

[Bruno Silva]

Hi guys,

well, in the moment i've an arquitecture like the picture annexed, the black one. A 3650 layer 3 switch is routing all the traffic of local vlan X to central vlan Y, throught the backbone vlan Z by OSPF.

the idea is put a new router with 4G card to create an alternative/backup route to central vlan.

How can i do this? creating a static routes? how will switch layer 3 detect principal routing fail?

thanks in advance!

[dbeattie]

Two standard ways of doing this are:

• Using a floating static route that points to the 4G path (use large AD on the ip route command). This will assert itself if the OSPF routes fail
• Running a tunnel (e.g. encrypted GRE) over the 4G path and establish OSPF over that path too. This path should be given a high OSPF cost so that it is only used if the main path is unavailable.

There other ways, but these are the most prevalent. If you have two dissimilar paths you could even look into SD-WAN!

Hope this helps

Dave