CST3607 Class Notes 2021-03-25

News & Tools

Subnetting Tutorial & Reference

Troubleshooting & Verifying Networks


  • At this point in the semester, you should be confident in your understanding of Cisco IOS, routing protocols, etc., to complete this Lab-04 (OSPF, Serial, DHCP), using only the network diagram as your guide, with 100% accuracy, in less than 30 minutes.
  • If that’s not the case, then you must practice, practice, practice, to gain the necessary skills and confidence.
  • Practice makes improvement.

OSPF Hello and Dead Interval

OSPF uses hello packets and two timers to check if a neighbor is still alive or not:

  • Hello Interval: defines how often we send the hello packet.
  • Dead Interval: defines how long we should wait for hello packets before we declare the neighbor dead.

Set the hello and dead intervals on interfaces which communicate with neighboring routers.

(config)# interface FastEthernet 0/0
(config-if)# ip ospf hello-interval <seconds>
(config-if)# ip ospf dead-interval <seconds> [ Defaults to four times the value of the hello interval ]

Show the Router ID, Hello, and Dead Intervals on an Interface

2621-A# show ip ospf interface s0/0

Serial0/0 is up, line protocol is up
   Internet address is, Area 0
   Process ID 100, Router ID, Network Type POINT-TO-POINT, Cost: 64
   Transmit Delay is 1 sec, State POINT-TO-POINT,
   Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
     Hello due in 00:00:02
   Index 2/2, flood queue length 0
   Next 0x0(0)/0x0(0)
   Last flood scan length is 1, maximum is 1
   Last flood scan time is 0 msec, maximum is 0 msec
   Neighbor Count is 1 , Adjacent neighbor count is 1
     Adjacent with neighbor
   Suppress hello for 0 neighbor(s)



VLAN (Virtual Local Area Network)

  • VLAN 1 is the default Ethernet VLAN
  • VLANs 1002 through 1005 are automatically created and cannot be deleted
  • What are the maximum number of VLANs, including the reserved VLANs?
  • Trunking
    • What is the purpose of a Trunk port?
  • IEEE 802.1Q Encapsulation

InterVLAN Routing

  • A Stub router, One-armed router or Router on a Stick (RonS) is a router configured to route traffic between virtual local area networks (VLANs).
  • It has only a single Ethernet NIC that is part of two or more Virtual LANs, enabling them to be joined.
  • The physical interface is divided into logical interfaces (known as sub-interfaces), one for each VLAN, configured as trunk interfaces.
  • Search: Router on a Stick

SVI (Switched Virtual Interface)

  • A Switch Virtual Interfaces (SVI) represents a logical Layer 3 interface on a switch.
  • VLANs divide broadcast domains in a LAN environment. Whenever hosts in one VLAN need to communicate with hosts in another VLAN, the traffic must be routed between them. This is known as inter-VLAN routing. On Layer 3 switches it is accomplished by the creation of Layer 3 interfaces (SVIs).

VLAN Diagnostic Commands

  • S1# show vlan
  • S1# show vlan brief
  • S1# show interface trunk
  • S1# show interfaces switchport
  • S1# show interface fa0/15 switchport
  • S1# show running-config
  • S1# show arp
  • S1# clear arp

VLAN Resources

Hands-On Lab-06: Troubleshooting Single Area OSPF

  • Use Cisco Packet Tracer v8.x
  • You must be present for this class, and submit your 100% Packet Tracer file, to get full credit for this lab.
  • This lab is due tonight before you sign off.
  1. Log into Cisco Packet Tracer
  2. Download and unzip the Lab-06 Packet Tracer file
  3. Rename the Packet Tracer with your last and first names
  4. Open Lab-06 Packet Tracer in Packet Tracer
  5. Save As: CST3607 Lab-06 YourLastName, YourFirstName v01
  6. Read the instructions!!!!!
  7. E-mail your 100% Lab-06 to me before you sign off. Subject: CST3607 Lab-06 YourLastName, YourFirstName
  • 1st password to log into a switch or router is the “console” password
  • 2nd password to get into privileged mode is the secret password

Read / Watch / Do

CCNA Certification Study Guide, Volume 2

  • Read Chapter 10 Access Lists
  • Do the Written Labs
  • Answer the Review Questions
    • Do not submit your answers for this chapter. The answers are in Appendix.

Read / Watch

Study for Exam 2

Better Focus and Efficient Studying When Not Multitasking