CCNA Complete Guide 2nd Edition.pdf - Cisco Learning Home

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- Below lists the <strong>Cisco</strong> IOS ping response codes: Response Code Description ! ICMP Echo Reply message received. . The ping command timed out while waiting for a reply. N ICMP Network Unreachable message received. ICMP Destination Unreachable – Host Unreachable (ICMP Type 3 Code 1) U message received. M ICMP Can’t Fragment message received. ICMP Source Quench message received, which normally indicates the Q destination host does not have sufficient processing buffer. ICMP Destination Unreachable – Port Unreachable (ICMP Type 3 Code 3) P message received. A Packet denied by access list. & TTL of packet (packet lifetime) was exceeded. ? Unknown packet received. - Troubleshooting scenario: Q: A host is able to ping to other hosts in the same subnet, but is unable to ping to a server in another subnet. What are the potential causes of this problem? A: Most likely due to subnet mask or default gateway misconfiguration on the host. - ICMP Source Quench messages are used for congestion control. They are sent by a congested router to notify the sending host to reduce its transmission rate as packets were discarded due to insufficient packet queue buffer. It is seldom being used as congestion control is often being performed by TCP at the transport layer. - ICMP Time Exceeded messages utilize the Time-to-Live (TTL) field in the IP header that indicates the period a packet can exist on a network when being delivered to the destination. Routers decrement the TTL by 1 whenever they forward a packet. Packets with TTL = 0 will be discarded, which can prevent IP packets from being circulated forever when routing loops occur. Upon decrementing the TTL value, a router must recalculate the Header Checksum of a packet. - Figure 10-2 shows how the Traceroute program on PC1, a Windows workstation, utilizes the IP TTL field (in ICMP Echo Requests) and ICMP TTL Exceeded messages to find the path to PC2. PC1 RT1 RT2 PC2 10.10.10.2 10.10.10.1 11.11.11.1 .2 12.12.12.1 TTL = 1 ICMP Echo Request ICMP TTL Exceeded Message TTL = 2 ICMP Echo Request ICMP TTL Exceeded Message TTL = 3 ICMP Echo Request ICMP Echo Reply Figure 10-2: Traceroute and ICMP TTL Exceeded Messages 73 12.12.12.2 Copyright © 2008 Yap Chin Hoong yapchinhoong@hotmail.com
- Firstly, PC1 purposely sends out an ICMP Echo Request packet with TTL = 1. RT1 which receives the packet will discard it and send out a ICMP TTL Exceeded message to PC1 as the TTL of the packet is decremented to 0. PC1 continues to send out another ICMP packet with TTL = 2, which causes RT2 to discard the packet and send out another ICMP TTL Exceeded message. - Standard Traceroute program sends sets of 3 ICMP Echo Requests for each increased TTL value. Hence the output provides 3 results for each TTL. Below shows the output of the tracert command on PC1: C:\>tracert -d 12.12.12.2 Tracing route to 12.12.12.2 over a maximum of 30 hops 1
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CCNA Complete Guide 2nd Edition Yap
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CCNA Complete Guide 2nd Edition Cop
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Upper Layers Lower Layers Applicati
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Cisco Hierarchical Model - Defined
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Header Length (4) Source Port (16)
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- Socket is a communication channel
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- The length of an IP address is 32
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- The following section discusses s
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- Below lists the 2 sublayers in th
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- Each switch port does not share t
Page 25 and 26: - Below lists the switch internal p
Page 27 and 28: Physical Layer - The physical layer
Page 29 and 30: - Another way to reduce emissions i
Page 31 and 32: Figure 3-7: Single-Mode and Multimo
Page 33 and 34: Wireless AP Switch Figure 3-8: 802.
Page 35 and 36: - Below lists the common IOS CLI er
Page 37 and 38: RT1#show running-config interface F
Page 39 and 40: - Cisco IOS treats a mistyped comma
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Page 43 and 44: - Below describes the STP convergen
Page 45 and 46: - Refer back to Figure 5-1B, assume
Page 47 and 48: - A switch running RSTP only need 6
Page 49 and 50: Port Security Configuration - Port
Page 51 and 52: SW2# 00:25:00: STP: VLAN0001 new ro
Page 55 and 56: - Both protocols utilize a 12-bit V
Page 57 and 58: Layer 4 Switching (Content Switchin
Page 59 and 60: - VTP Pruning provides a way to pre
Page 61 and 62: VLAN Trunking Protocol Configuratio
Page 63 and 64: - VLAN information will not be prop
Page 65 and 66: - Private IP addresses are non-rout
Page 67 and 68: - Some materials calculate the numb
Page 71 and 72: Cisco Discovery Protocol (CDP) c250
Page 73 and 74: - CDP is enabled by default. The no
Page 75: Troubleshooting IP - Internet Contr
Page 79 and 80: - Below describes the operation of
Page 81 and 82: Maximum Hop Count Hop count metric
Page 83 and 84: - Invalid Timer specifies how long
Page 85 and 86: - Initial configuration on RT2: Rou
Page 87 and 88: - Static Routing configuration on R
Page 89 and 90: - RIPv1 and IGRP are classful routi
Page 91 and 92: - IGRP configuration on RT2: RT2(co
Page 93 and 94: MISC IP Routing Commands - The pass
Page 95 and 96: - OSPF uses a reliable protocol to
Page 97 and 98: - OSPF areas break up a network so
Page 99 and 100: - EIGRP uses the same formula as us
Page 101 and 102: - Autosummarization EIGRP supports
Page 103 and 104: - OSPF Single-Area configuration on
Page 105 and 106: - The show ip ospf database EXEC co
Page 107 and 108: OSPF Multiarea Configuration Area 1
Page 109 and 110: - Below lists the different termino
Page 111 and 112: - Verify the EIGRP configuration on
Page 113 and 114: - When a link to a neighbor fails,
Page 115 and 116: - Below shows the beauty of VLSM. B
Page 117 and 118: - RT1 and RT3 are summarizing route
Page 121 and 122: - RIPv1 and IGRP perform autosummar
Page 123 and 124: RT1#sh ip route Gateway of last res
Page 125 and 126: MTU and Fragmentation - Maximum Tra
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- Figure 17-1 shows the usage of CI
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- Static NAT performs one-to-one ma
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172.16.1.1 172.16.1.2 172.16.1.3 17
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- Below shows the IP NAT debugging
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- The access list indicates whether
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- Access Control List (ACL) is the
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- Below lists some other usages of
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- Standard IP Access Lists configur
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RT2#sh access-lists example01 Exten
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WAN Network RT1 CSU/DSU CSU/DSU RT2
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Remote Access Technologies - Remote
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Digital Subscriber Lines (DSL) - DS
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Point-to-Point Serial Links (Leased
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- Comparisons between synchronous a
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- PPP Encapsulation configuration o
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- The function of the username {rem
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- 3 LMI protocol options are availa
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- Comparisons between Frame Relay L
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RT1 RT2 RT3 Figure 23-7A: RT1 with
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- IETF Frame Relay encapsulation ty
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RT1 Frame Relay RT2 DLCI 101 Frame
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- The interface serialx.y point-to-
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- Frame Relay Multipoint Subinterfa
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- Rate Shifting or Adaptive Rate Se
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- By operating in the 5GHz radio ba
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- Every packet from every access po
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Virtual Interface (mandatory) Servi
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Wireless Security - Organizations t
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Wireless Management - WLANs require
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Cisco Wireless LAN Configuration -
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- ISDN offers very fast call setup
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- ISDN was designed to reuse the ex
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- ISDN PRIs are often being used fo
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- Routing protocols are unable to l
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DDR Step 4: Determining when to ter
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- The show interfaces bri{num:0 | 1
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DDR Dialer Profiles Configuration -
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- Note: IP addresses are configured
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- Below show the routing tables on
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- The configuration above defines 2
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cisco Systems, Inc. 170 West Tasman
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Catalyst Switch IOS Upgrade Procedu
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Catalyst Switch IOS Upgrade Procedu
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Cisco Router Password Recovery Proc
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Catalyst Switch Password Recovery P
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Switch> Switch>en Switch#rename con
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- The 3 possible Frame Relay PVC st
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Constructing a Compound Frame Relay
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8. Once the frame is completed, it
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Decimal Hex Binary Decimal Hex Bina
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MISC Basic Networking Notes - The m
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MISC Data Link Layer Notes - Ethern
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- The 5-4-3 repeater deployment rul
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Ethernet Autonegotiation and Duplex
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The TCP Connection States timeout s
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- Q: How does a client application
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- Urgent Data Pointer (16 bits) ind
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TCP Selective Acknowledgment (SACK)
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- Local Proxy ARP is used when ther
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Spanning Tree Protocol Port ID - Wh
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The Problem of Router-on-a-Stick Co
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- Sample Subnet Zero configuration:
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The permanent keyword in the Static
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RIPv1 and VLSM RT1 RT4 Figure A6-9:
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- Below shows the NAT operations on
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Bidirectional (2-Way) NAT PC1 172.1
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- Note: A router does not require a
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The Access Control List established
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Switch Port Access Control Lists -
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- Below shows a sample Dynamic Acce
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Router(config)#ip access-list exten
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Optional PPP Commands - The compres
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- Below shows the output of the PPP
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- Below shows the output of the PPP
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- Below configure the username and
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IEEE 802.11 Standards and Specifica
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- Figure A6-20 shows the frame form
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- Below lists the IEEE 802.11 manag
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IEEE 802.11 Types and Subtypes Type
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Client (Supplicant) EAPOL-Start EAP
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- IPsec-based VPN is comprised of 2
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- IPsec supports the following 3 ty
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Version Header Length Time To Live
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- The authentication pre-share ISAK
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Troubleshooting ISDN E1/T1 Physical
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- Below addresses ISDN E1/T1 contro
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Troubleshooting ISDN Layer 2 - Unde
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Troubleshooting ISDN Layer 3 - Only
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ISDN Loopback Test Call - In a loop
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96 Number changed. The called numbe
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C2 Channel type not implemented. Th
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locking state, STP, 39 BNC, 27 bool
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show vlan, 57 show vtp status, 58 s
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framing, 22 MAC addresses, 22 stand
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K keepalives EIGRP, 95 Frame Relay,
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PAT (Port Address Translation), 127
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star topologies, 25 startup-config
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