1. Objectives
• Describe the usage and rules of access lists
• Establish standard IP access lists
• Apply access lists to interfaces
• Monitor and verify access lists
• Named access lists
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2. What are ACLs
• ACLs are lists of conditions that are applied to traffic
traveling across a router's interface.
• These lists tell the router what types of packets to accept
or deny.
• Acceptance and denial can be based on specified
conditions.
• ACLs can be configured at the router to control access to
a network or subnet.
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3. OSI Reference Model
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4. IP Packet
From TCP/IP Protocol Suite p.180 by Behrouz Forouzan McGrawHill
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5. Types of ACL
• Standard
• Extended
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6. How ACL Works
Standard ACL
Permit
Or ?
deny
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7. How to Identify different ACLs
Access List Types Number Range / Identifier
Standard 1 - 99, 1300 - 1999
Extended 100 - 199, 2000 - 2600
Name Name
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8. Scenario
192.168.2.0/24
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9. 192.168.1.0 11000000.10101000.00000001.00000000
192.168.1.1
192.168.1.2 00000000.00000000.00000000.11111111
192.168.1.3
Wildcard mask 0.0.0.255
.
. Subnet mask 255.255.255.0
.
.
192.168.1.254
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10. Summary
• ACLs are lists of conditions that are applied to traffic
traveling across a router's interface.
• Standard ACLs work based on source IP address.
• Standard ACLs should be configured on the router and
interface closest to the destination.
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11. Reference
McQuerry, Stephen. (2008) Interconnecting Cisco Network Devices,
Part 1 (ICND1): CCNA Exam 640-802 and ICND1 Exam 640-822, 2nd
Edition Cisco Press ISBN: 978-1-58705-462-4
Forouzan, Behrouz. (2009). Tcp/ip protocol suite. McGrawHill.
ISBN: 978-0070166783
Kelly Cannon, Kelly Caudle ,Anthony V. Chiarella (2009) CCNA Guide
to Cisco Networking Fundamentals, International Edition, 4th Edition
ISBN-13:9780840031198
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