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

P: [(0,X),(1,Q),2]

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:

**case a: **

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.

__Case b:__

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

**NOTE: 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” --- **

**B.Forouzan **

**F.Mosharraf **