system support & management protocols
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System support & Management Protocols. Lesson 13 NETS2150/2850. School of Information Technologies. Lecture Outline. Simple Network Management Protocol- SNMP Domain Name System- DNS Dynamic Host Configuration Protocol- DHCP. Network Management - SNMP. Simple Network Management Protocol - PowerPoint PPT PresentationTRANSCRIPT
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System support & Management Protocols
Lesson 13
NETS2150/2850School of Information Technologies
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Lecture Outline
Simple Network Management Protocol- SNMP
Domain Name System- DNS Dynamic Host Configuration Protocol-
DHCP
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Network Management - SNMP Simple Network Management Protocol Networks are becoming indispensable More complexity makes failure more likely Require automatic network management tools Standards required to allow multi-vendor networks Covering:
– Services– Protocols
– Management information base (MIB)
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Network Management Systems
Collection of tools for network management Single operator interface Powerful, user friendly command set Performing most or all management tasks Minimal amount of separate equipment
– i.e. use existing equipment View entire network as unified architecture Active elements provide regular feedback
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Key Elements
Management station or manager Agent Management information base Network management protocol
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Management Station Stand alone system or part of shared system Interface for human network manager Set of management applications
– Data analysis– Fault recovery
Interface to monitor and control network Translate manager’s requirements into monitoring
and control of remote elements Data base of network management information
extracted from managed entities
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Management Agent
Hosts, bridges, hubs, routers equipped with agent software
Allow them to be managed from management station
Respond to requests for information Respond to requests for action Asynchronously supply unsolicited
information
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Management Information Base MIB Representation of network resources as
objects Each object a variable representing one aspect
of managed object MIB is collection of access points at agent for
management of station Objects standardized across class of system
– Bridge, router etc.
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Network Management Protocol Link between management station and
agent TCP/IP uses SNMP OSI uses Common Management
Information Protocol (CMIP)
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Protocol Capabilities
Get Set Notify
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Management Layout
May be centralized in simple network May be distributed in large, complex
network– Multiple management servers– Each manages pool of agents– Management may be delegated to
intermediate manager
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Example of Distributed Network Management Configuration
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Network Management Protocol Architecture Application-level protocol Part of TCP/IP protocol suite Runs over UDP From management station, three types of SNMP messages
issued– GetRequest, GetNextRequest, and SetRequest – Port 161
Agent replies with GetResponse Agent may issue trap message in response to event that
affects MIB and underlying managed – Port 162
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SNMP v3: The latest version
Addresses security issues of SNMP v1/2
RFC 2570-2575 Proposed standard January 1998 Defines overall architecture and security
capability To be used with SNMP v2
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SNMP v3 Services Authentication
– Part of User-Based Security (UBS)– Assures that message:
• Came from identified source• Has not been altered• Has not been delayed or replayed
Privacy– Encrypted messages using DES
Access control– Can configure agents to provide a number of levels of access
to MIB– Access to information– Limit operations
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Domain Name System – DNSDomain Name System – DNS
Name Space Flat Hierarchical
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Domain Name Space
Was designed in order to have a hierarchical name space
Label Domain Name
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Domain name space
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Domain names and labels
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Domain Names: FQDN and PQDN
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Domains
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Distribution of Name SpacesDistribution of Name Spaces
Hierarchy of Name Servers Zone Root Server Primary and Secondary Servers
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Hierarchy of name servers
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Zones and domains
A primary server loads all information from the disk file; the secondary server loads all information from the primary server.
Note
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DNS In The InternetDNS In The Internet
Generic Domain
Country Domain
Inverse Domain
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DNS in the Internet
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Generic domains
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New generic domain labels New generic domain labels
Label Description
aero Airlines and aerospace companies
biz Businesses or firms (similar to com)
coop Cooperative business organizations
info Information service providers
museum Museums and other nonprofit organizations
name Personal names (individuals)
pro Professional individual organizations
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Country domains
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Inverse domain
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ResolutionResolution
Resolver Mapping Names to Addresses Mapping Addresses to Names Recursive Resolution Iterative Resolution Caching
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Recursive resolution
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Query and response messages
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DNS can use the services of UDP or TCP,
using the well-known port 53.
NoteNote::
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Dynamic Address Configuration
Each computer attached to the Internet must have:– Its own IP address– Its subnet mask– The IP address of a Router– The IP address of a name server
Usually stored in a config file– Used at bootup
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Dynamic Address Configuration…
How about first-time bootup? Diskless terminal? Or, the movement of a computer from
one subnet to another?– Protocols needed for on-demand config
(dynamically)– Example: DHCP
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DHCP Client-server program DHCP server: two databases
– First one: Statically binds physical addresses to IP addresses (Static db)
– Second one: makes DHCP dynamic (Dynamic db)• Temporary IP addresses are assigned consulting available
(unused) address pool• Valid for a negotiated time period only (leased)
– Must renew or stop using after the lease expires
– Renewal may or may not be granted by the server
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DHCP: Client Transition States
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Recommended Reading:– Stallings 22.3 (SNMP), – Forouzan 25 (DNS) & 19.2 (DHCP)