CCNA 4

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CCNA 4 Module 6 Network Management
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6.1.1 Workstations
UNIX or Linux can also serve as a desktop
operating system but are usually found on
high-end computers
Docking Station
Work Station

• Intercepts user data and application commands
• Directs the command to either
• the local operating system or
• the network interface card (NIC)
• Delivers transmissions from the network to the
  application

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6.1.1 Workstations

• A diskless workstation is a special computer that
  runs on a network.
• It has no disk drives but otherwise is a normal
  computer.
• Because they have no disk drives, it is not
  possible to upload data from the workstation or
  download anything to it.
• A diskless workstation cannot pass a virus onto
  the network, nor can it be used to take data from
  the network by copying this information to a disk
  drive.
• For this reason, such workstations are used in
  networks where security is paramount.

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6.1.2 Servers

• Hypertext Transfer Protocol (HTTP)
• File Transfer Protocol (FTP)
• Domain Name System (DNS)
• Simple Mail Transfer Protocol (SMTP)
• Post Office Protocol 3 (POP3)
• Internet Messaging Access Protocol (IMAP)
• File sharing protocols include Sun Microsystems
  Network File System (NFS)
• Microsoft Server Message Block (SMB).  
• Print services
• Dynamic Host Configuration Protocol (DHCP)
• Firewall Proxy or Network Address Translation
  (NAT) 

Some Windows operating systems may be installed
on both workstations and servers. The NT/2000/XP
versions of Windows software provide network
server capability.
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6.1.2 Servers

• Servers are typically larger systems than
  workstations
• Extra memory for multiple tasks that are active
  or resident in memory at the same time.
• Extra disk space for shared files and as an
  extension to the internal memory on the system.
• Extra expansion slots to connect shared devices,
  such as printers and multiple network interfaces.
• Multiprocessor systems are capable of executing
  multiple tasks in parallel by assigning each task
  to a different processor.
• Must function effectively under heavy loads.
• Redundancy is a feature of fault tolerant systems
  that are designed to survive failures and can be
  repaired without interruption while the systems
  are up and running.

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6.1.2 Servers
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6.1.2 Servers
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6.1.2 Servers

• One server running a NOS may work well when
  serving only a handful of clients.
• Most organizations use several servers.
• Typically
• one server for e-mail
• one server for file sharing
• one for FTP.

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6.1.3 Client-server relationship
From a NETWORK point of view, any computer
running TCP/IP (workstation or a server) is
considered a host.

• In a typical file server environment, the client
  would retrieve large portions of the database
  files to process the files locally.
• With client-server computing, the large database
  is stored, and the processing takes place on the
  server.
• A relatively small amount of data or results
  might be passed across the network.
• The workstation and server normally would be
  connected to the LAN by a hub or switch.

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6.1.4 Introduction to NOS
6.1.4 Introduction to NOS

• PerformanceA NOS must perform well at reading
  and writing files across the network between
  clients and servers. It must be able to maintain
  fast performance under heavy loads, when many
  clients are making requests. Consistent
  performance under heavy demand is an important
  standard for a NOS.
• Management and MonitoringThe management
  interface on the NOS server provides the tools
  for server monitoring, client administration,
  file, print, and disk storage management. The
  management interface provides tools for the
  installation of new services and the
  configuration of those services. Additionally,
  servers require regular monitoring and adjustment.

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6.1.4 Introduction to NOS
6.1.4 Introduction to NOS

• SecurityA NOS must protect the shared resources
  under its control. Security includes
  authenticating user access to services to prevent
  unauthorized access to the network resources.
  Security also performs encryption to protect
  information as it travels between clients and
  servers.
• ScalabilityScalability is the ability of a NOS
  to grow without degradation in performance. The
  NOS must be capable of sustaining performance as
  new users join the network and new servers are
  added to support them.
• Robustness/fault toleranceA measure of
  robustness is the ability to deliver services
  consistently under heavy load and to sustain its
  services if components or processes fail. Using
  redundant disk devices and balancing the workload
  across multiple servers can improve NOS
  robustness.

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6.1.5 Microsoft NT, 2000, and .NET
Windows 2000 Professional is not designed to be a
full NOS. It does not provide a domain
controller, DNS server, DHCP server, or render
any of the services that can be deployed with
Windows 2000 Server.

• Windows 2000 Server adds the normal
  server-specific functions.
• It provides integrated connectivity with Novell
  NetWare, UNIX, and AppleTalk systems and can also
  be configured as a communications server.
• Windows .NET Server is built on the Windows 2000
  Server kernel to run enterprise-level web and FTP
  sites.
• Equivalent to Linux and UNIX server operating
  systems.

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6.1.6 UNIX, Sun, HP, and LINUX

• Since its inception, UNIX was designed to support
  multiple users and multitasking.
• It was originally sold to run powerful network
  servers, not desktop computers.
• Solaris is currently the most widely used version
  of UNIX in the world for large networks and
  Internet websites.

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6.1.6 UNIX, Sun, HP, and LINUX

• Torvald's work led to a world-wide collaborative
  effort to develop Linux, an open source operating
  system that looks and feels like UNIX.
• Some advantages of Linux as a desktop operating
  system and network client
• It is a true 32-bit operating system.
• It supports preemptive multitasking and virtual
  memory.
• The code is open source and thus available for
  anyone to enhance and improve.
• Linux is less often deployed as a corporate
  desktop operating system.
• Recent distributions of Linux have networking
  components built in for connecting to a LAN,
  establishing a dialup connection to the Internet,
  or other remote network.
• TCP/IP is integrated into the Linux kernel
  instead of being implemented as a separate
  subsystem.

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6.1.7 Apple

• Mac OS X provides a new feature that allows for
  AppleTalk and Windows connectivity.
• The Mac OS X core operating system is UNIX-based.
• The Mac GUI resembles a cross between Windows XP
  and Linux X-windows GUI.

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6.1.8 Concept of service on servers

• Remote management allows administrators to
  configure networked systems that are miles apart.
  
• Network processes are referred to as
• services in Windows 2000
• daemons in UNIX and Linux.

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6.1.8 Concept of service on servers

• The two most common web server software packages
  are
• Microsoft Internet Information Services (IIS)
  Windows platform
• Apache Web Server Unix and Linux platform

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TCP/IP Based Services
6.1.8 Concept of service on servers

• Most popular network processes rely on the TCP/IP
  suite of protocols.
• TCP/IP are vulnerable to unauthorized scans and
  malicious attacks.
• Denial of service (DoS) attacks
• computer viruses
• fast-spreading Internet worms
• Recent versions of popular NOSs restrict the
  default network services.

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6.2.1 Introduction to network management
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6.2.1 Introduction to network management
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6.2.3 SNMP and CMIP standards

• Simple Network Management Protocol IETF
  community
• Common Management Information Protocol
  Telecommunications community

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6.2.4 SNMP operation

• Four elements of SNMP-based network management
• Management station (NMS)
• Management Agent
• Management Information Base (MIB)
• Network management protocol

• Things an Agent may track (items stored in MIB)
• Port and interface data
• TCP data
• ICMP data
• Number and state of its virtual circuits
• Number of certain kinds of error messages
  received
• Number of bytes and packets in and out of the
  device
• Maximum output queue length, for routers and
  other internetworking devices
• Broadcast messages sent and received
• Network interfaces going down and coming up

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6.2.4 SNMP operation

• The NMS is an ordinary workstation.   
• Large RAM, to hold all the co-resident management
  applications.
• Typical network protocol stack, such as TCP/IP.

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6.2.4 SNMP operation
Simple Network Management Protocol (SNMP) -
application layer protocol that facilitates the
exchange of management information between
network devices.
SNMP uses UDP over ports 161 and 162.
Eg. Packets per second sent on an interface
Eg. Color of the technicians shirt.
Eg. Number of open TCP connections
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6.2.4 SNMP operation

• SNMP protocol operates over UDP using port
  numbers 161/162
• Three message types common to SNMP
• Get management station retrieves information
  from an Agent
• Set/Put management station to set values on
  agent
• Trap agent notifies the management station of
  significant events.

SNMP can be enhanced through RMON (remote
monitoring). SNMP is required for RMON to
operate. RMON Agents are known as PROBES that
are located on each network segment. RMON probes
gather data about all frames on the segment and
transfer information to the NMS.
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6.2.4 SNMP operation
The RMON probe gathers management information
locally, The network manager periodically
retrieves a summary of this data.
SNMP
Proprietary
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6.2.4 SNMP operation
Central Manager sends out queries to all agents,
no matter where they are located.
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6.2.4 SNMP operation

• In a distributed network NMS can act in a
  client-server architecture.
• The clients send their data to the master server
  for centralized storage

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6.2.4 SNMP operation

• Distributed NMSs have equal responsibility, with
  their own manager databases.
• Management information is distributed over the
  peer NMSs.

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6.2.6 SNMP protocol
The agent is a software function embedded in most
networked devices, such as routers, switches,
managed hubs, printers, and servers.
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6.2.6 SNMP protocol
The initial protocol specification is referred to
as SNMPv1

• Interaction between the manager and the agent is
  facilitated by (SNMP).
• The term simple comes from the restricted number
  of message types that are part of the initial
  protocol specification.

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6.2.6 SNMP protocol

• MISCELLANEOUS FACTS
• The interaction between the manager and the
  managed device introduces traffic to the network.
  
• Aggressive monitoring strategies can negatively
  affect network performance.
• Bandwidth utilizations will go up, which may be
  an issue for WAN environments.
• Moreover, monitoring has a performance impact on
  the devices themselves being monitored, since
  they are required to process the manager
  requests.
• This processing should not take precedence over
  production services.
• A general rule is that a minimum amount of
  information should be polled as infrequently as
  possible.
• Determine which devices and links are most
  critical and what type of data is required.

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6.2.6 SNMP protocol
Each SNMP message contains a clear text string,
called a community string. The community string
is used like a password to restrict access to
managed devices.
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6.2.7 Configuring SNMP
ro (Optional) Specifies read-only access.
Authorized management stations are only able to
retrieve MIB objects.
rw (Optional) Specifies read-write access.
Authorized management stations are able to both
retrieve and modify MIB objects
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6.2.8 RMON

• RMON was developed to overcome limitations in the
  capabilities of SNMP. SNMP can store only limited
  amounts of information (counters for overall
  traffic, number of errors, etc.), and, as it is a
  polled system, network loading is high.
• RMON on the other hand, provides much more
  detailed information and offers a simplified
  manner of data collection.
• RMON makes use of a client (like a Network
  Management Console, a Protocol Analyzer, or a
  Network Analyzer like the new Fluke Networks
  OptiView). The client then gathers the statistics
  from either one or more agents. These agents can
  be stand-alone RMON probes (located in strategic
  spots in the network) and/or embedded RMON agents
  in routers and switches.

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6.2.9 Syslog

• The syslog utility is a mechanism for
  applications, processes, and the operating system
  of Cisco devices to report activity and error
  conditions.
• The syslog protocol is used to allow Cisco
  devices to issue these unsolicited messages to a
  network management station.
• To enable logging to all supported destinations
• Router(config)logging on
• To send log messages to a syslog server host,
  such as CiscoWorks2000
• Router(config)logging hostname ip address

To set logging severity level to level 6,
informational Router(config)logging trap
informational To include timestamp with syslog
message Router(config)service timestamps log
datetime