CN2668Routers and SwitchesKemtis KunanuraksapongMSIS with DistinctionMCTS, MCDST, MCP, A+

Agenda

•Chapter 3: TCP/IP•Exercise•Quiz

Overview of the TCP/IP

•Transmission Control Protocol/Internet Protocol▫A protocol suite

•TCP/IP Model▫Application▫Transport (TCP and UDP)▫Internetwork (IP Address)▫Network Interface▫See Figure 3-1 on Page 55

Application Layer

•Includes protocol for e-mail, remote logins, files transfer, web browsing, etc▫FTP/TFTP▫NFS (Network File System)▫SMTP▫Telnet▫DNS▫HTTP

Transport Layer

•Performs end-to-end packet delivery, reliability, and flow control▫TCP▫UDP

•Ports▫Well known Ports (1 – 1023)▫Registered Ports (1024 – 49151)▫Dynamic/Private Ports (49152 – 65535)

TCP Three-Way Handshake

•See Figure 3-3 on Page 59▫Src Port/Dest Port▫Seq. Nmber▫Ack. Number

•Initial sequence numbers (ISN) is required before two computers can communicatate▫Host A send SYN to Host B▫Host B send ACK to Host A▫Host A send ACK to Host B▫See Figure 3-4 on Page 60

TCP Sliding Windows

•Sliding windows control the flow and efficiency of communication▫After three-way handshake is complete▫Allows multiple packets to be sent and

affirmed with a single ACK packet▫Sender control the window’s size

Flow control method

•TCP Sliding Windows•Buffering

▫Store packets in the memory•Congestion avoidance

▫Slow down the transmission rate request

Internetwork Layer

•Handles software (logical) addressing•Four main protocols

▫IP▫ICMP▫ARP (Address Resolution Protocol)

Resolves IP address to MAC for source hosts▫RARP

Replaced by DHCP

Internetwork Layer (Cont.)

•ARP Tables▫Maintain in volatile RAM▫Contains MAC and IP addresses of other

devices on the network•ARP Request

▫Source host broadcast request when it can’t find the matching in the cache/ ARP Table. (Knows IP but no MAC)

Internetwork Layer (Cont.)

•ARP Request Frame▫See Figure 3-7 on Page 65▫Actual packets have 28 octets▫Destination MAC is FF:FF:FF:FF:FF:FF▫The destination send ARP reply back as

unicast•2 to 10 minute cache life

▫If used twice in the first 2 minutes, then it is extend to 10 minutes

Internetwork Layer (Cont.)

•RARP▫Same as ARP, except that it used for

diskless machine▫A client IP must be stored on a RARP

server•RARP Request Frame

▫See Figure 3-8 on Page 66•RARP Client

▫Receives a RARP reply from server and copy IP’s configuration to RAM till it’s reboot or shutdown

Internetwork Layer (Cont.)

•Routers and ARP▫Router maintain ARP table

•Ping Utility▫Use ICMP echo request/reply messages▫! means ping success▫See Table 3-1 on Page 68 for Ping

responses▫Standard Ping and Extended Ping

See Figure 3-10 on Page 69

Internetwork Layer (Cont.)

•Trace Utility▫Uses ICMP echo request/reply messages▫Shows the exact path a packet takes from

the source to destination

Frame Transmission

•The frame are sent to router when the packet is not on their segment

•Router remove the MAC address and determine which segment to forward the packet

Dynamic or Static Tables

•Static Table▫Has to be update manually by Network

Admin•Dynamic Table

▫Update are provided through routing protocols

▫Distance-vector algorithm Considers the number of hops between two

points▫Link state algorithm

Consider network traffic, connection speed, and other factors

Routing Packets

•See Figure 3-14 on Page 74▫Host A send packet to Router A▫Router 1 analyze the packet then forward

to Router 2 Router strip the Network Interface layer

information off the packet. Check the routing table for destination port Repack the packet with new MAC (MAC of

Router 2)▫Router 2 do the same and forward to

Router 3▫Router 3 analyze and send it to Host B

Cisco Three-Layer Hierarchical

•Core Layer▫Responsible for switching large amounts of

data quickly and efficiently•Distribution Layer

▫Provides networking services such as NAT, Firewall, QoS

▫IP addressing is managed at this layer•Access Layer (Desktop Layer)

▫Workstations / printers / End node•See Figure 3-15 on Page 77

Assignment

•Review Questions▫1 – 22

•Case Projects▫1, 2