Figure 2-21: Combining Horizontal and vertical Communication Recap App Transmission Control Protocol (TCP) Or User Datagram Protocol (UDP) Tran Irans Internet Protoco Source SwitchSwitch Router Switch Router Destination Host 2 3 2 Host 8-78-7 Figure 2-21: Combining Horizontal and Vertical Communication Int App DL Trans Phy Int Trans Int Int Source Host Destination Host Switch 1 Switch 2 Router 1 Switch 3 Router 2 Transmission Control Protocol (TCP) Or User Datagram Protocol (UDP) Internet Protocol (IP) Recap IP