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.
