How to which IP higher

[muarip6@gmail.com]

Higher IP is id of router but 

How to know which is higher 

Class-A/Class-B/Class-c

please explain me

[Predrag Jovic]

192 > 172 > 10

Higher means just higher value. Start from left and go to right compare octets, first higher octet wins.

10.255.255.255 < 11.0.0.1

[paul driver]

Hello

just like to add, router id's are not just selected by highest ip address, these can be superseded by manually specifying the router-id, which would take precedence over any active interface ip address ( including loopbacks)

But generally my understanding is that what has already been stated that its the classful ip range between a-c that is accounted for, with the most specific ( longest match) that its range being selected.

res
Paul

[Joseph W. Doherty]

For a router ID, whatever is numerically higher. This applies to both class ranges and numbering within a class range (also classless). Further, you're not limited to using an value within your IP address block you might be using although often router IDs correspond to a routable IP on the device.

For example, you could be using 192.168.1.0/24 and have a router ID of 200.0.0.1 or 1.2.3.4.