Cisco Certified Design
Associate
CCDA
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The
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.
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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.
1.
Application name
2.
Application type: Browser (HTTP), e-mail, database etc.
3.
Protocols - IP, IPX, SNA, AppleTalk etc.
4.
Number of users
5.
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.
1.
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.
2.
Ethernet_802.2 - The
default for NetWare 3.12 and later versions. Cisco
refers to this as SAP.
3.
Ethernet_II - This is also used with TCP/IP and DECnet.
Cisco refers to this as ARPA.
4.
Ethernet_SNAP - This
is also used with TCP/IP and AppleTalk. Cisco refers to
this as SNAP.
-
The specification 802.3z describes gigabit Ethernet over
fiber or shielded copper.
-
The specification 802.3ab (1000BaseT) describes gigabit
Ethernet over Category 5 UTP.
3.
Traffic pattern:
1.
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.
2.
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.
3.
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:
1.
RIP is useful for small networks.
2.
OSPF is a standards based, scalable protocol.
3.
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.
4.
Category
Routing Protocol
a.
Classless/ VLSM support EIGRP, OSPF, ISIS, RIP
v2, BGP
b.
Classful / No VLSM
RIP v1, IGRP
5.
Category
Routing Protocol
a.
Distance Vector
IP RIP, IPX RIP, IGRP, RTMP
b.
Link - State
OSPF, NLSP, ISIS
c.
Hybrid
EIGRP
6.
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:
1.
IPX RIP
2.
NetWare Link Services Protocol (NLSP)
3.
Enhanced IGRP for IPX
7.
APPN stands for Advanced Peer-to-Peer Networking. IBM
introduced APPN to overcome the limitations of
traditional Systems Network Architecture (SNA).
8.
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:
9.
Routing Protocol
Default update time (Sec)
IP RIP
30
IP IGRP
90
RTMP
10
IPX RIP
60
10. AppleTalk networks have three possible routing
protocols:
1.
Routing Table Maintenance Protocol (RTMP)
2.
Apple Talk Update - Based Routing Protocol (AURP)
3.
Enhanced IGRP for Apple Talk
Of these, RTMP is the most commonly used routing
protocol
11.
IGRP, EIGRP metrics:
i.
Bandwidth: This is represents the maximum throughput of a
link.
ii.
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.
iii.
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.
iv.
Delay: This is affected by the bandwidth and queuing delay.
v.
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:
1.
Application: Identify the applications that run on your
customer's network
2.
Application type: Categorize the application as a database,
groupware, Web etc.
3.
Number of Servers, hosts, and users: Note the number of
servers, hosts, and users using the specified
application.
4.
Segments: Locate the segments that the application flows.
7.
Hierarchical layer model:
1.
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:
i.
High reliability
ii.
Adapt to changes quickly
iii.
Lower latency
2.
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:
i.
Security
ii.
Access Control Lists
iii.
Route Summarization
iv.
Media translation
3.
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.
