# CS558 - Homework 8: TCP Hybla

• Verifying TCP Hybla window increase function in the slow start phase - for a specific ρ value

• Suppose:

 RTT = 0.1 sec RTT0 = 0.05 sec I.e., ρ = 2

Show that the following congestion window update:

 ``` WHi+1 = WHi + 2ρ - 1 = WHi + 3 ```

will result in the congestion window function

 ``` t t ρ ----- 2 ----- RTT RTT WH(t) = ρ * 2 = 2 * 2 ```

NOTE:

 you only need to verify for: t = RTT, 2*RTT and 3*RTT

In other words, verify that:

• WH(RTT) = 2 * 22*1 = 8.
• WH(2*RTT) = 2 * 22*2 = 2*16 = 32.
• WH(3*RTT) = 2 * 22*3 = 2*64 = 128.

NOTE: During a slow start, Hybla TCP sets WH = ρ (and not to 1) !

• Verifying TCP Hybla window increase function in the slow start phase - general value

• Repeat Question 1, but now use a general value for ρ

(I.e., do not assume that ρ = 2

Show that the following congestion window update:

 ``` WHi+1 = WHi + 2ρ - 1 ```

will result in the congestion window function

 ``` t ρ ----- RTT WH(t) = ρ * 2 ```

NOTE:

 you only need to verify for: t = RTT, 2*RTT and 3*RTT

In other words, verify that:

• WH(RTT) = ρ * 2ρ*1
• WH(2*RTT) = ρ * 2ρ*2
• WH(3*RTT) = ρ * 2ρ*3

NOTE: During a slow start, Hybla TCP sets WH = ρ (and not to 1) !