Transcript Installing Template Theme Files

Cisco Networking
Training
(CCENT/CCT/CCNA R&S)
Rick Rowe
Ron Giannetti
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
1
• Operation of IP Data Networks
Routers/Switches
• IP Routing Technologies
Static vs Dynamic
• TCP/IP Transport and Applications
• Only talking about IPv4 for the next few sessions
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
2
• TCP/IP Network Layer (3)
Defines how to deliver IP packets over the entire trip
• Functions
IP Routing
The process of hosts and routers forwarding IP Packets, while relying on the
underlying LANs and WANs to forward the bits
IP Addressing
Used to identify the packets source and destination hosts – organized into groups
IP Routing Protocol
A Protocol that dynamically learns the IP address groups to help deliver packets
Other Utilities
Other utilities that help the network layer (DNS, ARP, PING, etc)
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
3
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
4
• Different Layer 2 Technologies
• Not Scalable
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
5
• What happens when there is no logical grouping of numbers?
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
6
• IP provides common protocol
• IP provides unique addresses
What if phone companies assigned the same number to two different phones?
For communication to be possible, you need uniqueness
• Provides a structured addressing
Allows grouping of common addresses
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
7
• TCP/IP model dominates protocols
Many have existed
Two options – IPv4 and IPv6
Same kinds of Network layer functions, just different details
IP focuses on routing data
Not concerned with the physical transmission
Relies on lower layers to do that dirty work
Focuses on the logical details
How packets travel end to end over a TCP/IP network
Layer 3 = Packet
Layer 2 = Frame
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
8
• Routers and computers (hosts) use TCP/IP software
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
9
• A LAN includes all devices in the same broadcast domain
To reduce CPU overhead on each device by reducing the number of devices that receive each broadcast frame
To reduce security risks by reducing the number of hosts that receive copies of frames that the switches flood
(broadcasts, multicasts, and unknown unicasts)
To improve security for hosts that send sensitive data by keeping those hosts on a separate VLAN
To create more flexible designs that group users by department, or by groups that work together, instead of by physical
location
To solve problems more quickly, because the failure domain for many problems is the same set of devices as those in
the same broadcast domain
To reduce the workload for the Spanning Tree Protocol (STP) by limiting a VLAN to a single access switch
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
10
• Moving Data Between VLANs (hint.. Layer 2 switches won’t)
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
11
• Where do I send it?
PC1 does some basic analysis
Is the destination host in my same logical grouping? (IP Network or IP subnet)
If it isn’t, send it to my default router (default gateway)
PC1 sends to the “next hop” via the data link layer (Layer 2)
Use the destination link layer address
Uses ARP to find the link layer address
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
12
• All routers use the same general process to route packets
Each router has an IP Routing table
Table lists IP address Groupings (IP Networks or IP subnets)
Router compares a packet’s destination address to the routing table
Makes a match, entry tells where to forward the packet
Last router uses the same logic, but instead delivers to the end host
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
13
• Network Layer routing ignores the physical transmission details
Routing process forwards the network layer packet from end to end
Data link frame only takes a smaller part of the trip
Each successive data link layer frame moves the packet to the next device
• ARP
Each host and router must build a new
data link headers and trailers
ARP dynamically learns the data link
address of an IP host connected to a
LAN
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
14
• IP defines network layer addresses that identify any host or router
interface that connects to a TCP/IP network
Just like the mail, if you expect to receive mail, you need a postal address. If
you expect to receive an IP packet, you need an IP address
TCP/IP groups IP addresses together so that IP addresses used on the same
physical network are part of the same group (IP network or IP subnet)
Same as the postal service, nearby addresses are in the same postal code (ZIP code),
while all “nearby” IP addresses are in the same IP Subnet
“Nearby” IP addresses share the same Network portion of an address
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
15
• Both Hosts and Routers need to know about the internetwork
Hosts need to know their default router
Routers need to know routes so they can forward packets to each and every
network and IP subnet
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
16
• Static
Routes are manually defined
• Dynamic
Routes are dynamically learned
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
17
• If a device wants to communicate using TCP/IP, it needs an
address
• Any device that has at least one interface with an IP address can
send and receive IP packets and is called a Host
• 32-bit number, usually written in dotted-decimal notation (DDN)
• Each byte (8 bits) of the 32-bit IP address is shown as its decimal
equivalent
• 10101000 00000001 00000001 00000001 = 168.1.1.1
• Each DDN has four decimal octets, separated by periods
Octet = byte Each 8-bit octet can be a number between 0 and 255
• Each network interface has a unique IP address
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
18
• 4,294,967,296 addresses
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
19
• Grouping
Original specification for TCP/IP grouped IP addresses into sets of consecutive
addresses(IP networks).
The addresses in a single IP network have the same numeric value in the first
part of all addresses in a network
All IP addresses in the same group must not be separated from each other by
a router
IP addresses separated from each other by a router must be in different
groups
Only (1) ip address group per VLAN
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
20
• IPv4 address space includes all possible combinations of
numbers for the 32-bit IPv4 address.
0.0.0.0 – 255.255.255.255
• IP standards divide into classes, identified by the first octet
Class A gets roughly half
Class B gets ¼
Class C gets 1/8
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
21
• Unicast
Class A, B, and C define unicast addresses, meaning single host interface
• Mulitcast
Class D define multicast addresses, used to send on packet to multiple hosts
• IPv4 uses classes to define different sizes
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
22
• Identified by their Network IDs
Class A – first octet
Class B – first and second octet
Class C – first, second, and third octet
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
23
• Class ranges
Note – classful IP network refers to any Class A, B, or C network
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
24
• Defines methods of further subdividing the IPv4 address space
into groups that are smaller than a single IP network
• Flexible way to take a single Class A, B, or C IP network and
further subdivide into smaller consecutive IP addresses
• Instead of wasting addresses from a complete Class A, B, or C,
you can use a smaller subset
5 networks using classful
networks and no subnetting
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
25
• Instead using basic subnetting to break the Class B network
150.9.0.0 into five subnets
One group of the 254 addresses that begin with 150.9.1
One group of the 254 addresses that begin with 150.9.2
One group of the 254 addresses that begin with 150.9.3
Etc..
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
26
• Hosts use some routing logic
If the destination IP address is in the same IP subnet as I am, send the packet
directly to that destination host
Otherwise, send the packet to my default gateway(default router) – the router
has an interface on the same subnet as the host
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
27
• After receiving a data link frame addressed to the router
Use the data link Frame Check Sequence (FCS) field to ensure that frame has no errors
Discard old data link header and trailer, leaving the IP packet
Compare the IP Packet’s destination IP address to the routing table, find the route that
best matches the destination, the route identifies the outgoing interface, and possibly the
next hop IP address
Encapsulate the IP packet inside a new data link header and trailer, forward the frame
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
28
• Goals
Optimal Path Selection
Loop-free routing
Fast Convergence
Scalable networks
Limited administration
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
29
• Easy to use in smaller networks
• Not Scalable
• Most common type is the “default route”
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
30
• Primary tool for testing basic network connecitvity
Ping
Packet Internet Groper uses Internet Control Message Protocol (ICMP)
Sends an ICMP Echo request to another IP address
Device with that address should reply with an ICMP echo reply
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
31
• Remember that Ethernet devices communicate using the MAC
address
• If we’re using IP as our layer 3 protocol how do we translate this
to a MAC address?
• Using ARP!
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
32
• Address Resolution Protocol (ARP) maps IP addresses to MAC
addresses
• Each computer maintains a ARP table which maps IP addresses
to MAC addresses
• If the MAC address isn’t in the ARP table the computer
broadcasts a message to find the address
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
33
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
34
PC 1
Network
PC 2
“Where is PC 2?”
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
35
Broadcast Frame
PC 1
Layer 2
Layer 3
fffff…f
255.255.255.255
MAC DA
Protocol DA
Send Broadcast
to Everyone
192.168.1.2
Send Broadcast
to Everyone on
This Subnet
Network
What is the MAC
address of the
computer with this IP
address?
PC 1 Sends a Broadcast to find PC 2
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
36
Broadcast
PC 1
fffff…f
Switch Sees ffffff As
the Destination and
Sends This Frame to
Everyone
255.255.255.255
• Switch sends the broadcast frame out all
the ports within the broadcast domain
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
37
Server
Request for PC 2
Request for PC 2
Request for PC 2
Request for PC 2
PC 1
•
Request for PC 2
PC 2
All PCs see MAC address of FFFFFFFFFFFF so they all process the packet. PC2
responds with its IP and MAC address. PC1 uses this information to update it’s ARP
table.
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
38
© 2013 Cisco and/or its affiliates. All rights reserved.
Cisco Confidential
39