Few points about Count to Infifnity problem:
- This problem appears in DVR only not in LSR (Link state Routing)
This is a Possibility not a definite case . (why??) P-----Q-------X
let this is a connection that is already stabilised
now some how Q-----X is disconnected .
DVR of Q : [1,0,infinity], [generally DVR is applicable for 15 or lesser nodes therefore 16 refers infinity this is by convention as per “Foruzan”]
Here Comes two possible ways:
P sends its distance vector to Q as : [0,1,2]
After receiving this DV to Q
Q will start to count to infinity
and hence the DV of Q will be like: [1,0,3] as Q thinks P may have some path to X
because in DV we send the values only.
Q sends it DV to P and P recognizes that there is no link between Q----R
so, DV of P is updates and understood that there is no way to go X
So, among this two cases
MORE IMPORTANT POINTS:
- There are two ways to recover from this
a. Split Horizon
b. Poison reverse
Two nodes instability can be Solved by using the two approaches that are enlisted above but three node instability may or may not solvable by using this approaches too.
Refer this book
“Computer Networks: A Top Down Approach” ---