5.10 Module 10 -- Routing Fundamentals and Subnets
5.10 Module 10 -- Routing Fundamentals and Subnets
Routed/routable protocols -- between end-point hosts (Wikipedia:
Routing
)
IP (Wikipedia:
IPv4
)
TCP (Wikipedia:
Transmission_Control_Protocol
)
UDP (Wikipedia:
User_Datagram_Protocol
)
IPX, AppleTalk, Vines, DECnet, & XNS (Xerox Network System) ...
nonroutable protocols
NetBEUI (Wikipedia:
NetBEUI
)
bootp, dhcp
tunneling (Wikipedia:
Tunneling_protocol
)
Routing protocols router-to-router (Wikipedia:
Routing_Protocols
)
Router Information Protocol, RIP v1&v2 (Wikipedia:
Routing_Information_Protocol
)
Open Shortest Path First, OSPF (Wikipedia:
Open_Shortest_Path_First
)
Intermediate System to Intermediate System, IS-IS
Interior Gateway Routing Protocol, IGRP
Cisco Systems
proprietary "Enhanced IGRP", EIGRP
Exterior Gateway Protocol, EGP
Border Gateway Protocol, BGP
Interdomain Routing Protocol, IDRP
Constrained Shortest Path First, CSPF
IP packet -- Packet structure
Version
IP header length (Wikipedia:
IPv4
)
Type of Service -- Differentiated services/Explicit Congestion Notification
Total Length
Identification -- used during fragmentation
Flags
Fragment Offset
Time To Live, TTL Decremented by each router
Protocol --
>
137 (Wikipedia:
List_of_IPv4_protocol_numbers
)
1, Internet Control Message Protocol, ICMP (Wikipedia:
Internet_Control_Message_Protocol
)
6, Transmission Control Protocol, TCP (Wikipedia:
Transmission_Control_Protocol
)
17, User Datagram Protocol, UDP (Wikipedia:
User_Datagram_Protocol
)
89, Open Shortest Path First, OSPF (Wikipedia:
Open_Shortest_Path_First
)
Header Checksum -- Must be updated by each router
Source IP address
Destination IP address
Options
Date (Depends on protocol field)
Routing (Wikipedia:
Routing
)
Receive frame & remove from frame
use routing table and destination address to determine exit interface
fragment if necessary
decrement TTL and re-compute checksum
encapsulate in new frame & transmit frame
Routing protocols router-to-router (Wikipedia:
Routing_Protocols
)
Autonomous System (AS) (Wikipedia:
Autonomous_system_%28Internet%29
)
Interior
Exterior
Routing metrics
Hops (RIP (Wikipedia:
Routing_Information_Protocol
))
"Cost" (OSPF) (Wikipedia:
Open_Shortest_Path_First
)
Bandwidth (POTS modem/OC-192) (IGRP)
Link load (IGRP)
Delay (fiber/satellite) (IGRP)
Error rates (IGRP)
Sub-netting
Why? -- Reduce traffic & reduce broadcast domain sizes. Physical location.
Field width choices. Class A, B, & C. Zero and broadcast subnets.
Classless routing -- Classless Inter-Domain Routing (CIDR) (Wikipedia:
Classless_Inter-Domain_Routing
)
Subtract two. Both subnet field and host field.
Logical and-ing. IP address and subnet mask. Network determination. Subnet determination.
Subnet bit patterns
00000000 -- 0
10000000 -- 128 (
2
7
)
11000000 -- 192 (
128+64
)
11100000 -- 224 (
128+64+32
) (
255-31
)
11110000 -- 240 (
255-15
)
11111000 -- 248 (
255-7
)
11111100 -- 252 (
255-3
)
11111110 -- 254 (
255-1
)
11111111 -- 255 (
128+64+32+16+8+6+2+1
) (
256-1
) (
2
8
-1
)
Subnet configuration problems
UDP connectionless -- postcards (Wikipedia:
User_Datagram_Protocol
)
TCP connection-oriented -- bills/certified mail
TCP connection setup (from wikipedia) (Wikipedia:
Transmission_Control_Protocol
)
The active open is performed by sending a SYN to the server.
In response, the server replies with a SYN-ACK.
Finally the client sends an ACK (usually called SYN-ACK-ACK) back to the server.
Instructor: Louis Taber,
louis.taber.at.pima at gmail dot com
(520) 206-6850
My web
site
in
Cleveland
,
OH
The
Pima Community College
web site
5.10 Module 10 -- Routing Fundamentals and Subnets
