Chabot College
ELEC 99.08
Router Introduction
CISCO NETWORKING ACADEMY
What is a Router?
• A special purpose computer
• Hardware and software dedicated to path
selection and packet switching
• Cisco routers derived from Unix
computers
CISCO NETWORKING ACADEMY
PC vs. Router
• Temporary Storage (volatile)
RAM
RAM
RAM - Random Access Memory
DRAM - Dynamic Random Access Memory
Contents are lost when router is powered off.
CISCO NETWORKING ACADEMY
PC vs. Router
• Long-Term Storage (non-volatile)
Hard Disk
NVRAM
Non Volatile RAM
Contents are saved when router is powered off.
CISCO NETWORKING ACADEMY
PC vs. Router
• Serial Communications
Serial Interfaces
(COM1,COM2)
Used for
printers, modems
CISCO NETWORKING ACADEMY
Serial Interfaces
(S0, S1)
Used for WAN
PC vs. Router
• LAN Communications
Ethernet NIC
CISCO NETWORKING ACADEMY
Ethernet Interfaces
(E0, E1)
PC vs. Router
• Boot Instruction Sequence
ROM
CISCO NETWORKING ACADEMY
ROM
PC vs. Router
• Operating System
Windows
IOS
Internet Operating System
CISCO NETWORKING ACADEMY
PC vs. Router
• Flash memory function
Stores BIOS
CISCO NETWORKING ACADEMY
Stores IOS
PC vs. Router
• User interaction
Monitor
Keyboard
Mouse
CISCO NETWORKING ACADEMY
Terminal
(connects to console
port via “rollover” cable)
What is a Terminal?
• User box
– Monitor
– Keyboard
– Serial port (connects to host)
• Has no:
– CPU
– Storage
– Operating system
CISCO NETWORKING ACADEMY
Input: 100-240VAC
Freq: 50.60 Hz
Current: 1.2-0.6A
Watts: 40W
AUI
AUI
SERIAL 0
SERIAL 1
CONSOLE
AUX
CISCO 2514
SD
What is a “rollover” cable?
• Straight-through cable with connections
at one end completely reversed.
(Turn the rj-45 plug upside down on one end.)
• Connects to Cisco router console port.
CISCO NETWORKING ACADEMY
Router Port Summary
• Serial Interfaces
– WAN links
– Names: S0, S1
– V.35 Cable
• Ethernet Interfaces
– LAN links
– Names: E0, E1
– Transceiver / Twisted-pair cable
CISCO NETWORKING ACADEMY
Router Port Summary
• Console Port
– Terminal connection to configure router
– Name: con0
– Rollover cable
• Aux Port
– Modem connection to configure router
– Name: aux0
– Rollover cable
CISCO NETWORKING ACADEMY
Router Port Summary
• Virtual Terminal ports
– Virtual, not physical ports
– Users reach these ports via Telnet
– Names: vty0, vty1, vty2, vty3, vty4
CISCO NETWORKING ACADEMY
Router Capabilities
• Main Functions
– Path selection
– Packet switching
• Additional Functions
– Broadcast containment
– VLAN links
– Security / Access control
CISCO NETWORKING ACADEMY
Router Roles
• Network Edge
– WAN links to other sites in the enterprise
– WAN gateway to Internet
• Network Core
– Backbone links
– Collapsed backbone
• Anywhere
– Network segmentation device
– Security device
CISCO NETWORKING ACADEMY
Router Roles
• WAN links to other sites in the enterprise
– Example: connect Chabot to Las Positas
– Use serial ports
– Low bandwidth, compared to LAN (T-1 is
1.54 mbs)
– Cisco 2500 series router used frequently for
this role.
CISCO NETWORKING ACADEMY
Router Roles
• WAN Gateway to Internet
– Example: connects CLPCCD network to ISP
– Uses serial port
– Low bandwidth, compared to LAN (T-1 is
1.54 mbs)
– Cisco 2500 series router used frequently for
this role
CISCO NETWORKING ACADEMY
Router Roles
• Backbone links
– Connect user groups to backbone
– Use ethernet ports (or other LAN ports such
as token ring or FDDI)
– High bandwidth, (Typically 10 or 100 mbs)
– An older network design
– Cisco modular routers used frequently for
this role (e.g. 3600, 4000 series), but can be
done with 2514 in low traffic situations
CISCO NETWORKING ACADEMY
Router Roles
• “Collapsed Backbone”
– Backbone in a box; center of extended star
– Uses ethernet ports or fast ethernet ports
– A modern network design
– Uses high-end Cisco routers (e.g.7500 series)
– Router often works with large switches to
manage VLANS.
CISCO NETWORKING ACADEMY
Router Roles
• Network segmentation device
– Router links:
• networks
• subnets
• switch VLANS
– Broadcasts (usually) not forwarded
– Router works together with high-end switch
(ISL) or router module is part of the switch
CISCO NETWORKING ACADEMY
Router Roles
• Security device
– Access control rules allow router to control
traffic between:
• networks
• subnets
• switch VLANS
– Traffic regulated by “Access Control Lists”
CISCO NETWORKING ACADEMY
Router Roles
• The Cisco 7507 at the core of Chabot’s
net performs all these roles:
– WAN links to other sites in the enterprise
– Collapsed backbone
– Network segmentation device (VLAN links,
broadcast containment)
– Security device
CISCO NETWORKING ACADEMY
What is this router’s role?
Gateway to Internet
CISCO NETWORKING ACADEMY
What is this router’s role?
WAN link to a remote site in the company
San Francisco
Network
CISCO NETWORKING ACADEMY
San Jose
Network
What is this router’s role?
Backbone access
Science
Dept
CISCO NETWORKING ACADEMY
Engineering
Dept
Business
Dept
What is this router’s role?
“Collapsed Backbone”
RemoteOffice
Science
Dept
Administration
Dept
Engineering
Dept
CISCO NETWORKING ACADEMY
Business
Dept
What is this router’s role?
Network segmentation device
192.168.4.0
net
CISCO NETWORKING ACADEMY
192.168.5.0
net
What is this router’s role?
Network segmentation device
(linking VLANs)
VLAN
1
VLAN
1
CISCO NETWORKING ACADEMY
VLAN
2
VLAN
2
What is this router’s role?
Network segmentation device
(linking VLANs)
ISL Trunk
ISL, Cisco’s
Inter Switch Link,
manages traffic
from multiple
VLANs over a
single Ethernet pipe.
ISL is covered in
Semester 3.
CISCO NETWORKING ACADEMY
VLAN
1
VLAN
2
What is this router’s role?
Security device (firewall)
Access control rules:
1. Outbound traffic to Internet: YES
2. Inbound traffic from Internet: NO
CISCO NETWORKING ACADEMY
Assignment: Create a Visio drawing
showing routers in at least two of these
roles. Use logical network symbols.
• Network Edge
– WAN links to other sites in the enterprise
– WAN gateway to Internet
• Network Core
– Backbone links
– Collapsed backbone
• Anywhere
– Network segmentation device
– Security device
CISCO NETWORKING ACADEMY