GLBP & tracking ip routing

[louis_m]

Hi, anybody know how the tracking works on GLBP? Specifically, the tracking on the ip routing option?

[balaji.bandi]

GLBP with IP rouitng ( you mean in connection with IGP or static route ? - how it manipulate ?

or you looking the clarification of below command ?

track object-number interface type number {line-protocol | ip routing}

[louis_m]

I was just wondering how it detected changes. Sometimes we can lose our BGP routing but the next hop remains physically up. So line-protocol wouldn't work for us but IP routing might be a better fit depending on how it detects this and what causes it to change?

[balaji.bandi]

This is bit tricky but can be achiveable based on the behaviour how one like to failover based on conditional only.

you can track the ip routing / or protocol to flip over AVG to next one.

But again this case to case changes and how the network design also important. Most case BGP always have dual paths that auttomatically take care of TE. but gain as said this is pure design to achive the goal.

you need to create a use case and start working, so we can undertand better where we going, what problem we trying to solve.

Some time may not be required GLBP to take action, if the Routing taking care automatically.

[louis_m]

To be fair, the routers are directly connected and iBGP does take care of it so probably no need for the tracking on the GLBP side of things.

[balaji.bandi]

Suren that is what my point, we should make complicated with over engineering. hope you got the answer now.

[paul driver]

Hello
GLBP  tracking is used in conjunction with weighing on the tracked interface(s) so to determine as to which device will be the active virtual forwarder/gateway for the glbp group,

By default, the glbp group priority is set to 100 which is used to determine the AVG/AVF for the group, to specify the AVG/AVF for the group the higher priority is preferred and when tracking is applied a weight value can also be appended to decrease/increase this priority when those tracked interface(s) fail. Which decreases by a value of 10 for each tracked interface

So if you have a router tracking it upstream/downstream links then if either fail the default weighting is decrease by 10 if both fail then its decreased by 20, The priority and weighting can also be manually defined.

Lasty glbp preemption ISNT enabled by default so you need to make sure that is enabled also for failover to work.

Example
Preemption is enabled, group priority and weighting is manually applied. meaning if the threshold of the lower limit passed ( by both of the tracked interfaces failling ( decrements by 30) the other router in the glbp group will preempt to become the virtual forwader for the group.

Note: You can also incorporate ipsla with tracking if appicable.

AVG rtr
track 1 interface x/y line-protocol
track 2 interface y/y line-protocol

int x/x
lan facing interface
glbp x priority 200
glbp x preempt
glbp x weighting 115 lower 90 upper 105
glbp x weighting track 1 decrement 15
glbp x weighting track 2 decrement 15