FRR Multiple Backup Tunnels (Link Protection)

Load mpls.te.frr.multi.link.init.cfg

#IOS-XE
config replace flash:mpls.te.frr.multi.link.init.cfg

#IOS-XR (XR1, XR2 only)
configure
load bootflash:mpls.te.frr.multi.link.init.cfg
commit replace
y

There are two TE tunnels setup on the path CSR8-CSR9-CSR3-CSR2.

Configure CSR9 for link protection, using a different backup tunnel per primary LSP. One backup tunnel should use CSR9-CSR1-CSR3, and another should use CSR9-CSR10-CSR3.

Answer

#CSR9
ip explicit-path name CSR9-CSR1-CSR3
 next-address 1.1.1.1
 next-address 3.3.3.3
!
ip explicit-path name CSR9-CSR10-CSR3
 next-address 10.10.10.10
 next-address 3.3.3.3
!
int tun0
 tunnel dest 3.3.3.3
 ip unn lo0
 tunnel mode mpls traffic-eng 
 tunnel mpls traffic-eng path-option 1 explicit name CSR9-CSR1-CSR3
!
int tun1
 tunnel dest 3.3.3.3
 ip unn lo0
 tunnel mode mpls traffic-eng 
 tunnel mpls traffic-eng path-option 1 explicit name CSR9-CSR10-CSR3
!
int gi2.539
 mpls traffic-eng backup tun0
 mpls traffic-eng backup tun1

Explanation

We saw in the previous lab that multiple backup tunnels can be applied to an interface. When multiple NNHOP tunnels exist, the router is smart enough to figure out which ones match which primary LSPs.

When multiple link-protecting backup tunnels exist, all tunnels have the same destination. So the router will load share each primary LSP among the available backup tunnels. This allows you to share the load among multiple backup paths incase one single backup path can not handle the load of all primary LSPs.

We can verify this on CSR9: