ESET315HW7

ESET 315: Local And Metropolitan Area Networks Hwk7 – Due Monday, April 3 Name ___________________________________________ References: Hint: Always remember this in the binary calculation of IP addresses: Bit 7 2^7=128 Bit 6 2^6=64 Bit 5 2^5=32 Bit 4 2^4=16 Bit 3 2^3=8 Bit 2 2^2=4 Bit 1 2^1=2 Bit 0 2^0=1 Your subnet number has all host bits equal to 0. This how you can find the: - First address: it is the Subnet number + 1 - Broadcast address: all host bits are set to 1 - Last address: the broadcast address – 1 Note: Host bits are in “red” in the examples below. Question 1 (18 points): Please complete the next three problems: A) Address: 138.128.129.5 / 19 (or 138.128.129.5/255.255.224.0) Subnet chart: Byte 1 Byte 2 Byte 3 Byte 4 Address Mask Subnet Number First Address Last Address Broadcast Address Class: ________ Number of usable IP addresses: _________________ B) Address: 200.129.4.20 / 255.255.255.224 (or 200.129.4.20/27) Subnet chart: Byte 1 Byte 2 Byte 3 Byte 4 Address Mask Subnet Number First Address Last Address Broadcast Address Class: ________ Spring 2023 1

ESET 315: Local And Metropolitan Area Networks Introduction to Layer 3 - Practice Problems Number of usable IP addresses: _________________ C) Address: 200.129.4.25 / 255.255.255.252 (or 200.129.4.25/30) Subnet chart: Byte 1 Byte 2 Byte 3 Byte 4 Address Mask Subnet Number First Address Last Address Broadcast Address Class: ________ Number of usable IP addresses: _________________ Question 2 (Learning bridges) (18 points) As you remember, a Layer 2 switch is an example of a learning bridge. Then, let us consider hosts X, Y, Z, W and learning bridges B1, B2, and B3, with initially empty forwarding tables, as in Figure 2. Figure 2 – A single subnet with 3 bridges a) Suppose Y sends to Z. Which bridges learn where Y is? _________Does X’s network interface see this packet? ______ Show the current tables for B1, B2, and B3 Spring 2023 2

ESET 315: Local And Metropolitan Area Networks Introduction to Layer 3 - Practice Problems b) After the FTP server replies to Host D in VLAN3 (Room 1003) (make sure to show the cumulative table) Spring 2023 4