Andrew Smith 1 VLSM and CIDR Variable Length Subnet Masking and Classless inter-domain routing.
111 © 2003, Cisco Systems, Inc. All rights reserved. RECAP VLSM and CIDR.
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Transcript of 111 © 2003, Cisco Systems, Inc. All rights reserved. RECAP VLSM and CIDR.
111© 2003, Cisco Systems, Inc. All rights reserved.
RECAP
• VLSM and CIDR
222© 2003, Cisco Systems, Inc. All rights reserved.
VLSM Labs
333© 2003, Cisco Systems, Inc. All rights reserved.
• The largest subnet requires 400 hosts = 29
– 2 = 510 possible hosts
• 192.168.0001100x.xxxxxxxx = .24.0/23
• The next largest subnet requires 200 hosts = 2 8 – 2 = 254 possible hosts
• 192.168.00011010.xxxxxxxx = .26.0 /24
444© 2003, Cisco Systems, Inc. All rights reserved.
• The next largest subnet requires 50 hosts = 26 – 2 = 62 possible hosts
• 192.168.00011011.00xxxxxx = .27.0/ 26
• The next largest subnet requires 50 hosts = 26 – 2 = 62 possible hosts
• 192.168.00011011.01xxxxxx = .27.64/ 26
555© 2003, Cisco Systems, Inc. All rights reserved.
CIDR / Supernetting Example
• Company A requires 945 IP addresses
• Using the old system it can be assigned either a Class B address or 4 Class C address
• This would generate 4 entries in the ISP routing table
666© 2003, Cisco Systems, Inc. All rights reserved.
• Using CIDR the ISP is able to use four consecutive IP address
• 200.10.0.0 / 24
• 200.10.1.0 / 24
• 200.10.2.0 / 24
• 200.10.3.0 /24
• This block can be summarised as 200.10.0.0/ 22
777© 2003, Cisco Systems, Inc. All rights reserved.
In Binary
• 200.10.00000000.0 / 22
• 200.10.00000001.0 / 22
• 200.10.00000010.0 / 22
• 200.10.00000011.0 /22
• This allows bits borrowed from the network portion to be given to host addresses
8© 2003, Cisco Systems, Inc. All rights reserved.
CCNA 3 v3.0 Module 2 Single-Area OSPF
999© 2003, Cisco Systems, Inc. All rights reserved.
Objectives
• Link-state routing protocol
• Single-area OSPF concepts
• Single-area OSPF configuration
101010© 2003, Cisco Systems, Inc. All rights reserved.
Link-state routing protocols perform the following functions:
• Respond quickly to network changes
• Send triggered updates only when a network change has occurred
• Send periodic updates known as link-state refreshes
• Use a hello mechanism to determine the reachability of neighbors
111111© 2003, Cisco Systems, Inc. All rights reserved.
Overview of Link-State and Distance Vector Routing
121212© 2003, Cisco Systems, Inc. All rights reserved.
How Routing Information Is Maintained
131313© 2003, Cisco Systems, Inc. All rights reserved.
Link-State Routing Features
P4 knows about its neighbors, P1 and P3, on Perth3 network
141414© 2003, Cisco Systems, Inc. All rights reserved.
Link-State Routing Protocol Algorithms
151515© 2003, Cisco Systems, Inc. All rights reserved.
Advantages and Disadvantages of Link-State Routing
161616© 2003, Cisco Systems, Inc. All rights reserved.
Comparing Distance Vector and Link-State Routing
171717© 2003, Cisco Systems, Inc. All rights reserved.
OSPF Overview
OSPF is becoming the preferred IGP protocol when compared with RIPv1 and RIPv2 because it is scalable.
181818© 2003, Cisco Systems, Inc. All rights reserved.
OSPF Terminology
191919© 2003, Cisco Systems, Inc. All rights reserved.
More OSPF Terminology
Cost = 100,000,000 / Bandwidth
202020© 2003, Cisco Systems, Inc. All rights reserved.
OSPF Databases
212121© 2003, Cisco Systems, Inc. All rights reserved.
Comparing OSPF Link State with Distance Vector Routing Protocols
222222© 2003, Cisco Systems, Inc. All rights reserved.
Shortest Path Algorithm
The best path is the lowest-cost path.
Router B has calculated the best path to D
232323© 2003, Cisco Systems, Inc. All rights reserved.
OSPF Network Types
242424© 2003, Cisco Systems, Inc. All rights reserved.
OSPF Hello Protocol
252525© 2003, Cisco Systems, Inc. All rights reserved.
Steps in the Operation of OSPF
Discover neighbors
262626© 2003, Cisco Systems, Inc. All rights reserved.
Steps in the Operation of OSPF
Elect DR and BDR on Multi Access Network
272727© 2003, Cisco Systems, Inc. All rights reserved.
Steps in the Operation of OSPF
Selecting the Best Route
282828© 2003, Cisco Systems, Inc. All rights reserved.
Basic OSPF Configuration
292929© 2003, Cisco Systems, Inc. All rights reserved.
Basic OSPF Configuration
303030© 2003, Cisco Systems, Inc. All rights reserved.
Configuring OSPF Loopback Address and Router Priority
313131© 2003, Cisco Systems, Inc. All rights reserved.
Setting OSPF Priority
The priorities can be set to any value from 0 to 255. A value of 0 prevents that router from being elected. A router with the highest OSPF priority will win the election for DR.
323232© 2003, Cisco Systems, Inc. All rights reserved.
Modifying OSPF Cost Metric
333333© 2003, Cisco Systems, Inc. All rights reserved.
Configuring OSPF Authentication
343434© 2003, Cisco Systems, Inc. All rights reserved.
Configuring OSPF Timers
353535© 2003, Cisco Systems, Inc. All rights reserved.
OSPF - Propagating a Default Route
363636© 2003, Cisco Systems, Inc. All rights reserved.
Common OSPF Configuration Issues
373737© 2003, Cisco Systems, Inc. All rights reserved.
Verifying OSPF Configuration
• show ip protocol
• show ip route
• show ip ospf interface
• shop ip ospf
• show ip ospf neighbor detail
• show ip ospf database
383838© 2003, Cisco Systems, Inc. All rights reserved.
The debug and clear Commands for OSPF Verification