Cisco® CCDA Exam Cram Notes : Routed And Switched Networks Involving Lan, Wan, And Dial Up Access

CCDA certification is a foundation exam for testing Cisco network design fundamentals for the small office/home office (SOHO) market. CCDA certified professionals could design routed and switched networks involving LAN, WAN, and dial up access for small businesses.The exam is of 2 hours duration and there will be approximately 65 questions. Many questions are scenario based. Click here to visit official Cisco website to know more about this certification. CCDA is a pre-requisite for CCDP (Cisco Certified Design Professional) certification offered by Cisco Systems.

1. When designing a network, document the application characteristics. This should include present and future applications. Following are some important characteristics that need to be documented.

  • Application name
  • Application type: Browser (HTTP), e-mail, database etc.
  • Protocols - IP, IPX, SNA, AppleTalk etc.
  • Number of users
  • Number of hosts

2. Ethernet, Token Ring, and Fiber Optic:

  • Token ring frame doesn't have a preamble, whereas Ethernet frame has 7/8 bytes preamble for each frame transmitted. A Token Ring frame starts with an SD (Starting Delimiter) of size 1 byte. FDDI frame have a preamble of 8 bytes (64 bits).
  • Maximum size of collision domains for 100BaseFX multimode fiber is 412 meters in half duplex and 2000m if full duplex is used.
  • Loop back and collision detection should be disabled when you are running full duplex Ethernet.
  • The Routing Information Field (RIF) of a Token Ring frame contains the Route Descriptor. The route descriptor in turn contains the Ring Number and Bridge Number.
  • In Source Route Bridging (SRB), the source node finds the routes to the destinations on a network using explorer frames. This is different from Ethernet transparent bridging; the bridges build and maintain tables (MAC tables) containing paths to destinations.
  • Source Route Transparent bridging (SRT) enables a bridge to function as both a source-routing bridge and a transparent bridge.
  • In Token Ring network, when an explorer frame arrive at the destination, the destination node sets the D - bit (Direction bit) to 1 and sends the frame back to the source node, indicating successful route discovery.
  • There are four different Ethernet framing types. Although several encapsulation types can share the same interface, clients and servers with different types cannot communicate without a router.
    • Ethernet_802.3 - The default for NetWare versions 2.x through 3.11. This is also the default for Cisco routers. Cisco refers to this as Novell-ether.
    • Ethernet_802.2 - The default for NetWare 3.12 and later versions. Cisco refers to this as SAP.
    • Ethernet_II - This is also used with TCP/IP and DECnet. Cisco refers to this as ARPA.
    • Ethernet_SNAP - This is also used with TCP/IP and AppleTalk. Cisco refers to this as SNAP.

3. Traffic pattern:

  • Terminal / Host: Applications based on Terminal / Host are low - volume character traffic. The traffic from the terminal will be a few characters while the Host returns screen full of characters.
  • Client / Server: The traffic flow in Client / server environment is bi-directional and asymmetric. Traffic sent to the host is usually less than 100 bytes and the return traffic from the host can be more than 1500 bytes. HHTP, FTP are examples of Client / Server Protocols.
  • Peer/ Peer: In peer-to-peer environment, traffic flow is bi-directional and symmetric. Peer to peer communication is commonly used in work groups.

4. Routing protocols:

  • RIP is useful for small networks.
  • OSPF is a standards based, scalable protocol.
  • IGRP and EIGRP are Cisco proprietary routing protocols. EIGRP is preferred when there are multiple routed protocols such as IP, IPX etc. Cisco's IGRP and EIGRP can load balance traffic across multiple routes that have unequal metrics by using "variance" command.
  • Category     Routing Protocol
    • Classless/ VLSM support   EIGRP, OSPF, ISIS, RIP v2, BGP
    • Classful / No VLSM   RIP v1, IGRP
  • Category   Routing Protocol
    • Distance Vector   IP RIP, IPX RIP, IGRP, RTMP
    • Link - State   OSPF, NLSP, ISIS
    • Hybrid   EIGRP
  • NLSP (Netware Link Services Protocol) is a Link State Routing Protocol, and supports hierarchical routing with area, domain, and global internetwork components. Group of networks form an area. A group of areas form a domain. A group of domains form a global internetwork. Novell NetWare networks have three options for routing:
    • IPX RIP
    • NetWare Link Services Protocol (NLSP)
    • Enhanced IGRP for IPX
  • APPN stands for Advanced Peer-to-Peer Networking. IBM introduced APPN to overcome the limitations of traditional Systems Network Architecture (SNA).
  • IP RIP based networks send the complete routing table during update. The default update interval is 30 seconds. Major distance vector protocol Update timers are as below:
  • Routing Protocol   Default update time (Sec)
    • IP RIP   30
    • IP IGRP   90
    • RTMP   10
    • IPX RIP   60
  • AppleTalk networks have three possible routing protocols:
    • Routing Table Maintenance Protocol (RTMP)
    • Apple Talk Update - Based Routing Protocol (AURP)
    • Enhanced IGRP for Apple Talk
    • Of these, RTMP is the most commonly used routing protocol
  • IGRP, EIGRP metrics:
    • Bandwidth: This is represents the maximum throughput of a link.
    • MTU (Maximum Transmission Unit): This is the maximum message length that is acceptable to all links on the path. The larger MTU means faster transmission of packets.
    • Reliability: This is a measurement of reliability of a network link. It is assigned by the administrator or can be calculated by using protocol statistics.
    • Delay: This is affected by the bandwidth and queuing delay.
    • Load: Load is based among many things, CPU usage, packets processed per sec.

5. IP, IPX are examples of routed protocols. RIP, EIGRP are examples of routing protocols.

6. Identifying information and traffic flows is part of characterizing the customer's application. The following fields can help identify the traffic flows:

  • Application: Identify the applications that run on your customer's network
  • Application type: Categorize the application as a database, groupware, Web etc.
  • Number of Servers, hosts, and users: Note the number of servers, hosts, and users using the specified application.
  • Segments: Locate the segments that the application flows.

7. Hierarchical layer model:

  • Core layer: Designed for high availability and redundancy. Core layer is the high-speed switching backbone of any network. The core layer has the following characteristics:
    • High reliability
    • Adapt to changes quickly
    • Lower latency
  • Distribution layer: Address summarization and media translation are applied in the distribution layer. Distribution layer lies in between the Core layer and Access layer. It usually addresses the following:
    • Security
    • Access Control Lists
    • Route Summarization
    • Media translation
  • Access layer: The access layer consists of the remote office sites using ISDN, Frame Relay etc. Local area networks segments are also part of the access layer.

8. Cisco ConfigMaker is used for configuring networks using Cisco Switches and Cisco routers. At present, ConfigMaker can't support some high-end devices like 7000 series routers. It can be used to configure small networks of Cisco routers (800, 1000, 1600, 1700, 2500, 2600, 3600, and 4000 series), switches, and Hubs from a single PC.

9. CiscoWorks is a suite of integrated network management tools that will help an administrator in maintenance of small to medium sized business networks.

Cisco View is a GUI based device management software application that provides dynamic status, statistics, and configuration information. Cisco View graphically displays a real time physical view of Cisco devices.

TACAC+ (Terminal Access Controller Access Control System +): provides complete network access security (NAS) for dial-in connections.

10. Configuration management refers to base lining, modifying, and tracking configuration changes of network devices.

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