Managed Object - Telkom University

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Transcript Managed Object - Telkom University

SNMP Network Management (I)*
*Mani
Subramanian “Network Management: Principles and
practice”, Addison-Wesley, 2000.
SNMP Network Management
 Organization Model
 Communication Model
 Information Model
o Structure
of
Management
Information (SMI)
o Managed Objects
o Management
Information
Base
(MIB)
 SNMP Administrative Model
 SNMP Protocol Specs
Organization Model
 Describes components of a




network management system
Focuses on functions and
infrastructure
Objects are network elements
such as hubs, bridges, routers,
etc.
Managed elements have a
process running on them called
an agent
Manager queries the agent,
gets information, processes it
and stores it in the MIB
MIB
SNMP Manager
agent
agent
Managed Objects
Unmanaged Objects
A simplified hierarchical
(2-tier) setup
Organization Model
Multiple managers, 1 agent
 An agent responds to any
management system that
communicates with it
using SNMP
 A NMS provided by a
vendor is in a better
position to manage,
monitor and configure all
NEs coming from that
same vendor
MIB
SNMP Manager
SNMP Manager
Managed
agent
Object
Managed Objects
Managers may have restricted
access to managed objects
Organization Model
 Limiting the data that a
manager wishes to obtain!
 RMON (Remote
Monitoring): acts as an
agent and a manager


RMON gathers data from
MO, analyses the data, and
stores the data
Communicates the
statistics to the manager
MIB
SNMP Manager
SNMP Manager
Managed
agent
Object
Managed Objects
RMON Probe
Managers may have restricted
access to managed objects
3-tier architecture
Organization Model
 Proxy server converts
non-SNMP data from nonSNMP objects to SNMP
compatible objects and
messages
MIB
SNMP Manager
Proxy Server
Managed
agent
Object
Wireless LAN
Managed Objects
unmanaged
Objects
Introduction to SNMP
SNMP Network Management
 Organization Model
 Communication Model
 Information Model
o Structure
of
Management
Information (SMI)
o Managed Objects
o Management
Information
Base
(MIB)
 SNMP Administrative Model
 SNMP Protocol Specs
Communication Model
MANAGER
AGENTS
MIB
Communication Model
 Communicate mgnt information between network
mgnt stations and managed elements
 Goals:
o
o
o
Management functions maintained by agents are kept
simple
Protocol flexibility (addition of new aspects of operation
and management)
Transparency (should not be affected by the architecture
of particular hosts and gateways)
 Operation: 5 messages
o
o
get-request, get-next request, set-request
get-response, trap
 SNMP messages are exchanged using UDP (connection
less) transport protocol: ports 161 and 162
Communication Model
SNMP Manager
SNMP messages
SNMP agent
UDP
UDP
IP
IP
DLC
DLC
PHY
PHY
Network or
Internet
Physical Medium
Trap
Get-Response
SNMP Agent
Application
Set-Request
Application
Manages objects
Trap
Get-Response
Set-Request
GetNext-Request
Get-Request
SNMP Manager
Application
GetNext-Request
Management
Data
SNMP Agent
Get-Request
SNMP Manager
Communication Model-SNMP Traps
Type
Cold-start of a system
Warm-start of a system
Indication
Agent is reinitializing itself since its
configuration has changed
Agent is reinitializing itself but
its configuration has not changed
Link down
Link failure
Link up
Link restoral
Failure of Authentication
Request does not have proper authentication
e.g., wrong SNMP community string
EGP neighbor loss
Exterior Gateway protocol neighbor gone
Enterprise specific
Specific to vendor implementing it
Communication Model-SNMP Traps
Type
Format
Cold-start of a system
Warm-start of a system
Link down
Link up
Failure of Authentication
EGP neighbor
loss
Enterprise
specific
generic-trap
INTEGER {
coldStart
(0),
warmStart
(1),
linkDown
(2),
linkUp
(3),
authenticationFailure (4),
egpNeighborLoss
(5),
enterpriseSpecific
(6)
}
SNMP Network Management
 Organization Model
 Communication Model
 Information Model
o Structure of Management Information
(SMI)
o Managed Objects
o Management Information Base (MIB)
 SNMP Administrative Model
 SNMP Protocol Specs
Structure of Management Information
 RFC 1155: Structure of Management Information
 A common representation for data between both
manager and agent
 Defines the syntax (using ASN.1) to describe
management information
o
o
Data types and
Rules used to define managed objects in a MIB
 Generic objects and private (vendor specific) objects
conforming to SMI rules (RFC 1155) can be managed
by SNMP
SMI, Objects and Instances
 Objects have: object
types and object
instances
 SMI is concerned with
types and not instances
 Object type



Name (unique descriptor
and object identifier)
Syntax (ASN.1)
Encoding (BER)
Object
Object
Type
Name:
OBJECT
IDENTIFIER
Syntax:
ASN.1
Object
Instance
Encoding:
BER
Managed Object : Type and Instance
SMI, Objects and Instances
Object
NMS
192.168.252.110
Object
Type
172.17.252.1
Name:
OBJECT
IDENTIFIER
Router 2
Backbone Network
Syntax:
ASN.1
Object
Instance
Encoding:
BER
Managed Object : Type and Instance
Router 1
172.16.46.1
Hub 1
172.16.46.2
Hub 2
172.16.46.3
A Managed LAN Network
A hub is an object type
A hub with IP 172.16.46.3 is an
instance of the object
SMI, Objects and Instances
Title: System Information: 172.16.46.2
Name or IP Address: 172.16.46.2
System Name
System Description
System Contact :
System Location
System Object ID
System Up Time
:
: 3Com LinkBuilder FMS, SW version:3.02
:
: .iso.org.dod.internet.private.enterprises.43.1.8.5
: (2475380437) 286 days, 12:03:24.37
System Information on 172.16.46.2 Hub
Name:
OBJECT
IDENTIFIER
Title: System Information: 172.16.46.3
Name or IP Address: 172.16.46.3
System Name
System Description
System Contact :
System Location
System Object ID
System Up Time
:
: 3Com LinkBuilder FMS, SW version:3.12
:
: .iso.org.dod.internet.private.enterprises.43.1.8.5
: (3146735182) 364 days,4:55:51.82
System Information on 172.16.46.3 Hub
Object
Object
Type
Syntax:
ASN.1
Encoding:
BER
Object
Instance 3
Object
Instance 2
Object
Instance 1
Managed Object : Type with Multiple Instances
SMI, Names
root
 Each managed object is
associated with an
identifier (OBJECT
IDENTIFIER)


Identifiers are used to
name objects and they are
unique for managed
objects
identifier is a sequence of
integers
ccitt(0)
iso(1)
joint-iso-ccitt(2)
org(3)
internet(1)
mgmt(2)
mib-2(1)
dod(6)
private(4)
experimental(3)
enterprise(1)
internet OBJECT IDENTIFIER ::= { iso(1) org(3) dod(6) 1 }
::= {1 3 6 1 }
Name of managed object
::= {iso standard dod internet}
SMI, Names
Internet
{1 3 6 1}
directory
(1)
Reserved for
future use
mgmt
(2)
experimental
(3)
private
(4)
To identify objects used
in Internet experiments
Used for objects defined in
IAB-approved documents
Used heavily by
commercial vendors
Sub-nodes under Internet
SMI, Names
Internet
{1 3 6 1}
directory
(1)
mgmt
(2)
experimental
(3)
mib-2
(1)
system (1)
interfaces (2)
at (3)
ip (4)
icmp (5)
snmp (11)
transmission (10)
cmot (9)
egp (8)
udp (7)
tcp (6)
private
(4)
SMI, Names
Internet
{1 3 6 1}
directory
(1)
mgmt
(2)
experimental
(3)
private
(4)
enterprises
(1)
cisco
(9)
hp
(11)
3Com
(43)
Cabletron
(52)
SMI, SNMP Syntax
SNMP ASN.1
Data Type
Tag
Structure
Number
Class
Simple
or
Primitive
Defined
or
Application
Constructor
or
Structured
Universal
Application
Contextspecific
Private
SNMP Primitive Data Types
Data Type
INTEGER
Comments
Subtype INTEGER (n1..nN)
Special case: Enumerated INTEGER type
OCTET STRING
8-bit bytes binary and textual data
Subtypes can be specified by either
range or fixed
OBJECT IDENTIFIER Object position in MIB
NULL
Placeholder
 Special case of INTEGER
 Subtype:



INTEGER (0..255)
OCTET STRING (SIZE 0..255)
OCTET STRING (SIZE 8)
data type (enumeration):
error-status INTEGER {
noError(0)
tooBig(1)
genErr(5)
authorizationError(16)
}
Application-Wide SNMP Types
IpAddress ::= [APPLICATION 0] IMPLICIT
160.85.128.1
OCTET STRING (SIZE (4)) A0 55 80 01
Counter
::= [APPLICATION 1] IMPLICIT
INTEGER (0..4294967295)
0
231
Gauge
::= [APPLICATION 2] IMPLICIT
INTEGER (0..4294967295)
0
231
0 1 2
TimeTicks ::= [APPLICATION 3] IMPLICIT
INTEGER (0..4294967295)
0 10 20 [ms]
Opaque
::= [APPLICATION 4] IMPLICIT
OCTET STRING
SNMP Structured Types
 SEQUENCE,SEQUENCE OF
 SET and SET OF of ASN.1 are not included in SNMP-
based management
 Used to build lists and tables
SEQUENCE {<type1>, <type2>,….., <typeN>}
1
2
3
4
5
6
Object
ipAdEntAddr
ipAdEntIfIndex
ipAdEntNetMask
ipAdEntBcastAddr
ipAdEntReasmMaxSize
ipAddrEntry
Managed objects
OBJECT IDENTIFIER
{ipAddrEntry 1}
{ipAddrEntry 2}
{ipAddrEntry 3}
{ipAddrEntry 4}
{ipAddrEntry 5}
{ipAddrTable 1}
ObjectSyntax
IpAddress
INTEGER
IpAddress
INTEGER
INTEGER
SEQUENCE
Their location in Their data types
the MIB
SNMP Structured Types
List:
IpAddrEntry ::=
SEQUENCE {
ipAdEntAddr
IpAddress
ipAdEntIfIndex
INTEGER
ipAdEntNetMask
IpAddress
ipAdEntBcastAddr
INTEGER
ipAdEntReasmMaxSize
INTEGER (0..65535)
}
Managed Object IpAddrEntry as a list
7
Object Name
ipAddrTable
Table: ipAddrTable ::=
SEQUENCE OF
OBJECT IDENTIFIER
{ip 20}
Syntax
SEQUENCE OF
IpAddrEntry
Managed Object ipAddrTable as a table
ipAddrTable is made up of instances of IpAddrEntry object
SMI, Encoding
 Basic Encoding Rules, BER
 Data Types and Tags
Type
Tag
OBJECT IDENTIFIER
UNIVERSAL 6
SEQUENCE
UNIVERSAL 16
IpAddress
APPLICATION 0
Counter
APPLICATION 1
Gauge
APPLICATION 2
TimeTicks
Opaque
APPLICATION 3
APPLICATION 4
 Encoding of Object Identifiers: Packs the first two
integers into a single sub-identifier
SMI, Encoding
enterprise OBJECT IDENTIFIER ::=
{iso(1) org(3) dod(6) internet(1) private(4) 1}
X
Y
Z = 40·X + Y
43
0
06
6
1
0
05
2B
0
06
4
0
01
04
1
0
01
Managed Objects
system(1)
sysDescr(1) sysObjectID(2) sysUpTime(3)
sysContact(4)
 Textual name: mnemonic; always begins with lower case
o
OBJECT IDENTIFIER: unique position of the managed object
in the MIB
 Syntax: the ASN.1 definition of the object type
 Access: read-only, read-write, not-accessible (e.g., tables)
 Status: mandatory, optional, obsolete
 Definition: textual description of the object type
Managed Objects
system(1)
sysDescr(1) sysObjectID(2) sysUpTime(3)
OBJECT:
sysDescr:
Syntax:
Definition:
Access:
Status:
sysContact(4)
{ system 1 }
OCTET STRING
"A textual description of the entity. This value
should include the full name and version
identification of the system's hardware type,
software operating-system, and networking
software. It is mandatory that this only contain
printable ASCII characters."
read-only
mandatory
Specifications for System Description
Macros for Managed Objects
 A formal definition for managed objects
IMPORTS
ObjectName, ObjectSyntax FROM RFC-1155-SMI
OBJECT-TYPE MACRO ::=
BEGIN
TYPE NOTATION ::=
“SYNTAX” type(TYPE ObjectSyntax)
“ACCESS” Access
“STATUS” Status
VALUE NOTATION ::= value(VALUE ObjectName)
Access ::= “read-only” | “write-only” | “notaccessible”
Status ::= “mandatory” | “optional” | “obsolete”
END
OBJECT-TYPE Macro
SMI Definitions
RFC1155-SMI DEFINITIONS ::= BEGIN
EXPORTS
--EVERYTHING
internet, directory, mgmt, … OBJECT-TYPE, ObjectName, ObjectSyntax,…
-- the path to the root
internet
OBJECT IDENTIFIER ::= {iso org(3) dod(6) 1}
directory …
…
-- definition of object types
OBJECT-TYPE MACRO ::=
BEGIN
TYPE NOTATION ::= “SYNTAX” type(TYPE ObjectSyntax)
“ACCESS” Access
“STATUS” Status
VALUE NOTATION ::= value(VALUE ObjectName)
Access ::= “read-only” | “write-only” | “not-accessible”
Status ::= “mandatory” | “optional” | “obsolete”
END
-- names of objects in the MIB
ObjectName ::= OBJECT IDENTIFIER
-- syntax of objects in the MIB
ObjectSnytax ::= CHOICE{simple SimpleSyntax, application-wide ApplicationSyntax}
SimpleSyntax :: CHOICE{number INTEGER, string OCTET STRING, object OBJECT
IDENTIFIER, empty NULL}
ApplicationSyntax :: CHOICE{address NetworkAddress, counter Counter, gauge Gauge,
ticks TimeTicks, arbitrary Opaque}
…
…
END
Macros for Managed Objects
 Using OBJECT-TYPE MACRO to define a managed object
of the system group in the MIB
sysDescr OBJECT-TYPE
SYNTAX DisplayString (SIZE(0..255))
ACCESS read-only
STATUS mandatory
DESCRIPTION
“A textual description of the entity. This
value should include the full name and version
identification of the system’s hardware type,
software operating-system, and networking software.
It is mandatory that this only contain printable
ASCII characters.”
::= { system 1 }
Macros for Managed Objects
system(1)
sysDescr(1) sysObjectID(2) sysUpTime(3)
sysContact(4)
sysUpTime OBJECT-TYPE
SYNTAX TimeTicks
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The time (in hundredths of a second)
since the network management portion of
the system was last re-initialized."
::= { system 3 }
Aggregate Objects
 A group of related objects (also called tabular objects)
 Represented by a table with
o
o
Columns of objects
Rows of instances
 Example: IP address table
 Consists of objects:






IP address
Interface
Subnet mask (which subnet this address belongs to)
Broadcast address (value of l.s.b. in IP broadcast address)
Largest IP datagram that can be assembled
Multiple instances of these objects associated with the node
Aggregate Object Macro-ipAddrTable (RFC 1155)
ipAddrTable OBJECT-TYPE
Syntax SEQUENCE OF IpAddrEntry
Access not-accessible
STATUS mandatory
Definition "The table of addressing information
relevant to this entity's IP addresses."
::={ip 20}
ipAddrEntry OBJECT-TYPE
Syntax IpAddrEntry
Access not-accessible
STATUS mandatory
Definition "The addressing information for one of this
entity's IP addresses..„
INDEX {ipAdEntAddr}
::={ipAddrTable 1}
IpAddrEntry ::= SEQUENCE {
ipAdEntAddr
ipAdEntIfIndex
ipAdEntNetMask
ipAdEntBcastAddr
ipAdEntReasmMaxSize
IpAddress,
INTEGER,
IpAddress,
INTEGER,
INTEGER (0..65535)}
Aggregate Object Macro-ipAddrTable (RFC 1155)
ipAdEntAddr OBJECT-TYPE
Syntax IpAddress
Access read-only
STATUS mandatory
Definition "The IP address to which this entry's
addressing information pertains."
::={ipAddrEntry 1}
ipAdEntIfIndex OBJECT-TYPE
Syntax INTEGER
Access read-only
STATUS mandatory
Definition "The index value that uniquely identifies the
interface to which this entry is applicable. The interface identified
by a particular value of this index is the same interface as identified
by the same value of IfIndex."
INDEX {ipAdEntAddr}
::={ipAddrEntry 2}
.
.
.
.
Columnar Objects
 Aggregate objects type contains one or more subtypes
each could have multiple instances, with a value associated with
each instance
 It is convenient to conceptually define a tabular structure for objects
with multiple values
o e.g., IP address table
o
 The objects TABLE T and ENTRY E are
logical objects
o
TABLE
T
ENTRY
E
define grouping, are not accessible
 Columnar objects are objects that
represent the attributes
o
hence are accessible
 Each instance of E is a row of columnar
COLUMNAR COLUMNAR COLUMNAR COLUMNAR COLUMNAR
OBJECT 1
OBJECT 4 OBJECT 5
OBJECT 2 OBJECT 3
objects 1 through 5
 Multiple instances of E are represented
by multiple rows
Multiple Instance Managed Object
Columnar Objects
T
Object ID
Not accessible
{Table, Entry, Object, Index}
Row 3:
the third
instance of
the object
T.E
T.E.1.1
T.E.2.1
T.E.3.1
T.E.4.1
T.E.5.1
T.E.1.2
T.E.2.2
T.E.3.2
T.E.4.2
T.E.5.2
T.E.1.3
T.E.2.3
T.E.3.3
T.E.4.3
T.E.5.3
T.E.1.4
T.E.2.4
T.E.3.4
T.E.4.4
T.E.5.4
Example of 5 Columnar Object with 4 Instances (rows)
Notice that the column-row numeric designation is
reverse of that used in matrix representation (row-column)
Columnar Objects - Example
ipAddrTable {1.3.6.1.2.1.4.20}
ipAddrEntry (1)
ipAdEntAddr (1)
ipAdEntIfIndex (2)
ipAdEntNetMask (3)
ipAdEntBcastAddr (4)
ipAdEntReasmMaxSize (5)
Columnar object ID
of ipAdEntBcastAddr is (1.3.6.1.2.1.4.20.1.4):
iso org dod internet mgmt mib ip ipAddrTable ipAddrEntry ipAdEntBcastAddr
1 3 6
1
2 1 4
20
1
4
Columnar objects under ipAddrEntry
Row
ipAdEntAddr
ipAdEntIfIndex
IpAdEntNetMask
IpAdEntBcastAddr
IpAdEntReasmMaxSize
1
123.45.2.1
1
255.255.255.0
0
12000
2
123.45.3.4
3
255.255.0.0
1
12000
3
165.8.9.25
2
255.255.255.0
0
10000
4
9.96.8.138
4
255.255.255.0
0
15000
4 instances of the
Columnar object
Index of table
Object instances of ipAddrTable (1.3.6.1.2.1.4.20)
Columnar Objects - Example
Row
ipAdEntAddr
ipAdEntIfIndex
IpAdEntNetMask
IpAdEntBcastAddr
IpAdEntReasmMaxSize
1
123.45.2.1
1
255.255.255.0
0
12000
2
123.45.3.4
3
255.255.0.0
1
12000
3
165.8.9.25
2
255.255.255.0
0
10000
4
9.96.8.138
4
255.255.255.0
0
15000
Node 1 under
ipAddrEntry
Object instances of ipAddrTable (1.3.6.1.2.1.4.20)
Columnar Object
Object ID for
ipAddrEntry
Row #
Object Identifier
ipAdEntAddr
1.3.6.1.2.1.4.20.1.1
2
{1.3.6.1.2.1.4.20.1.1.123.45.3.4}
ipAdEntIfIndex
1.3.6.1.2.1.4.20.1.2
3
{1.3.6.1.2.1.4.20.1.2.165.8.9.25}
ipAdEntBcastAddr
1.3.6.1.2.1.4.20.1.4
1
{1.3.6.1.2.1.4.20.1.4.123.45.2.1}
IpAdEntReasmMaxSize
1.3.6.1.2.1.4.20.1.5
4
{1.3.6.1.2.1.4.20.1.5.9.96.8.138}
Object Id for specific instances
Index of the
object instance
Management Information Base (MIB)
 RFC 1213
 MIB is a database containing information about




elements to be managed
For SNMP, the MIB is a structured database (tree)
Each resource to be managed is represented by an
object
Each system (e.g., a router) maintains a MIB that
reflects the status of its managed resources
A NMS monitors/controls the resources by
reading/modifying the values of objects in the MIB
MIB, RFC1213
Internet
{1 3 6 1}
 Implementation can be done
as needed (e.g., objects
essential for fault or
configuration management
are added)
 If a group is implemented by
a vendor, all its components
are implemented (e.g.
OSPF and all its group
objects)
directory
(1)
mgmt
(2)
experimental
(3)
mib-2
(1)
system (1)
interfaces (2)
at (3)
ip (4)
icmp (5)
snmp (11)
transmission (10)
cmot (9)
egp (8)
udp (7)
tcp (6)
<module name>
<imports>
<definitions>
END
private
(4)
DEFINITIONS ::= BEGIN
Internet MIB-II Group
MIB, RFC1213
-- groups in MIB-II
RFC1213-MIB DEFINITIONS ::= BEGIN
IMPORT mgmt, NetworkAddress, IpAddress,
Counter, Gauge, TimeTicks
FROM RFC1155-SMI
OBJECT-TYPE
FROM RFC-1212;
-- This MIB module uses the extended
-- OBJET-TYPE macro as defined in [14];
--
MIB-II (same prefix as MIB-I)
mib-2
OBJECT IDENTIFIER ::= { mgmt 1 }
-- textual conventions
DisplayString ::=
OCTET STRING
-- This data type is used to model textual
-- information taken from the NVT ASCII character
-- set. By convention, objects
-- with this syntax are declared as having
--SIZE (0..255)
system
interfaces
OBJECT IDENTIFIER ::= { mib-2 1}
OBJECT IDENTIFIER ::= { mib-2 2 }
at
OBJECT IDENTIFIER ::= { mib-2 3 }
ip
OBJECT IDENTIFIER ::= { mib-2 4 }
icmp
OBJECT IDENTIFIER ::= { mib-2 5 }
tcp
OBJECT IDENTIFIER ::= { mib-2 6 }
udp
OBJECT IDENTIFIER ::= { mib-2 7 }
egp
OBJECT IDENTIFIER ::= { mib-2 8 }
cmot
OBJECT IDENTIFIER ::= { mib-2 9 }
transmission OBJECT IDENTIFIER ::= {mib-2 10}
PhysAddress ::=
OCTET STRING
-- This data type is used to model media
-- addresses. For many types of media, this will
-- be in a binary representation. For example,
-- an ethernet address would be represented as
-- a string of 6 octets.
snmp
.
.
.
.
END
OBJECT IDENTIFIER ::= { mib-2 11 }
MIB, System Group
-- the System group
-----
Implementation of the System group is
mandatory for all systems. If an agent is not
configured to have a value for any of these
variables, a string of length 0 is returned.
sysDescr OBJECT-TYPE
SYNTAX DisplayString (SIZE (0..255))
ACCESS read-only
STATUS mandatory
DESCRIPTION
the entity. ……."
::= { system 1 }
"A textual description of
system
(mib-2 1)
sysDescr (1)
sysObjectId
(2)
sysUpTime (3)
sysServices (7)
sysLocation (6)
sysName (5)
sysContact (4)
sysObjectID OBJECT-TYPE
sysUpTime OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
SYNTAX TimeTicks
ACCESS read-only
ACCESS read-only
STATUS mandatory
STATUS mandatory
DESCRIPTION "The vendor's
DESCRIPTION
authoritative identification of the network
"The time (in hundredths of
management subsystem contained in the
a
second)
since
the
network management
entity."
portion of the system was last
::= { system 2 }
reinitialized."
::= { system 3 }
MIB, System Group
Fault monitoring:
By periodically polling each agent for this value; if the current
value is less than the most recent value, then the agent has
been restarted since last poll!
Entity
sysDescr
sysObjectID
sysUpTime
sysContact
sysName
sysLocation
sysServices
OID
system 1
system 2
system 3
system 4
system 5
system 6
system 7
Description (brief)
Textual description
OBJECT IDENTIFIER of the entity
Time (in hundredths of a second since last reset)
Contact person for the node
Administrative name of the system
Physical location of the node
Value designating the layer services provided by the
entity
Programmed by vendor of
objects during
manufacturing time
MIB, Interface Group
interfaces
(mib-2 2)
 It specifies the number of
interfaces in a network
component and the
managed objects
associated with each
interface

E.g., Ethernet bridge with
many network interface
cards
 Implementation: mandatory
ifNumber
(1)
ifTable
(2)
ifEntry
(1)
ifIndex (1)
ifDescr (2)
ifType (3)
ifMtu (4)
ifSpeed (5)
ifPhysAddress (6)
ifAdminstatus (7)
ifOperStatus (8)
ifLastChange (9)
ifInOctets (10)
ifInUcastPkts (11)
interfaces OBJECT IDENTIFIER ::= { mib-2 2 }
ifSpecific (22)
ifOutQLen (21)
ifOutErrors (20)
ifOutDiscards (19)
ifOutNUcastPkts (18)
ifOutUcastPkts (17)
ifOutOctets (16)
ifUnknownProtos (15)
ifInErrors (14)
ifInDiscards (13)
ifInNUcastPkts (12)
MIB, Interface Group
interfaces
(mib-2 2)
ifNumber OBJECT-TYPE
SYNTAX INTEGER
ifNumber
ifTable
ACCESS read-only
(1)
(2)
STATUS mandatory
DESCRIPTION "The number of network
ifEntry
interfaces (regardless of their current
(1)
state) present on this system."
ifEntry OBJECT-TYPE
::= { interfaces 1 }
SYNTAX IfEntry
ifTable OBJECT-TYPE
ACCESS not-accessible
SYNTAX SEQUENCE OF IfEntry
STATUS mandatory
ACCESS not-accessible
DESCRIPTION "An interface entry
STATUS mandatory
containing objects at the sub-network
layer and below for a particular
DESCRIPTION "A list of interface
interface."
entries. The number of entries is
given by the value of ifNumber."
INDEX
{ ifIndex }
::= { interfaces 2 }
::= { ifTable 1 }
IfEntry ::= SEQUENCE {ifIndex INTEGER, ifDescr DisplayString, ifType INTEGER,
ifMtu INTEGER, ifSpeed Gauge, ifPhysAddress PhysAddress, ifAdminStatus INTEGER,
ifOperStatus INTEGER, ifLastChange TimeTicks, ifInOctets Counter, ……}
MIB, Interface Group
interfaces
(mib-2 2)
 Basic information useful for
network management such as
performance monitoring and
fault control
Examples
 1)-measuring the queue length
or the total number of octets
into/out of the system-
indicators for detecting
congestion
 2)- measuring the traffic rate on
a given interface!


ifInUcastPkts/second,
ifOutUcastPkts/second
Counter data types, always
incrementing!
ifNumber
(1)
ifTable
(2)
ifEntry
(1)
ifIndex (1)
ifDescr (2)
ifType (3)
ifMtu (4)
ifSpeed (5)
ifPhysAddress (6)
ifAdminstatus (7)
ifOperStatus (8)
ifLastChange (9)
ifInOctets (10)
ifInUcastPkts (11)
ifSpecific (22)
ifOutQLen (21)
ifOutErrors (20)
ifOutDiscards (19)
ifOutNUcastPkts (18)
ifOutUcastPkts (17)
ifOutOctets (16)
ifUnknownProtos (15)
ifInErrors (14)
ifInDiscards (13)
ifInNUcastPkts (12)
MIB, IP Group
ip
(mib-2 4)
 Contains information relevant
to the implementation and
operation of IP at a node
ipForwarding (1)
 Routers periodically execute
routing algorithms and update
routing tables
ipRoutingDiscards (23)
ipDefaultTTL (2)
ipNetToMediaTable (22)
ipInReceives (3)
ipRouteTable (21)
ipInHdrErrors (4)
ipAddrTable (20)
ipInAddrErrors (5)
ipFragCreates (19)
ipFragFails (18)
ipForwDatagrams (6)



IP Address Table contains
table of IP addresses
IP Route Table contains an
entry for each route
IP Network-to-Media Table
is address translation table
mapping IP addresses to
physical addresses
ipInUnknownProtos (7)
ipFragOKs (17)
ipInDiscards (8)
ipReasmFails (16)
ipInDelivers (9)
ipOutRequests(10)
ipOutDiscards (11)
ipReasmOKs (15)
ipReasmReqds (14)
ipReasmTimeout (13)
ipOutNoRoutes (12)
MIB, IP Group
ip
(mib-2 4)
Gateway or router
TTL in IP header
Total # packets
received from interfaces
# of discarded datagrams
due to header errors
ipForwarding (1)
ipRoutingDiscards (23)
ipDefaultTTL (2)
ipNetToMediaTable (22)
ipInReceives (3)
ipRouteTable (21)
ipInHdrErrors (4)
ipAddrTable (20)
ipInAddrErrors (5)
ipFragCreates (19)
ipFragFails (18)
ipForwDatagrams (6)
ipInUnknownProtos (7)
ipFragOKs (17)
ipInDiscards (8)
ipReasmFails (16)
ipInDelivers (9)
ipOutRequests(10)
ipOutDiscards (11)
ipReasmOKs (15)
ipReasmReqds (14)
ipReasmTimeout (13)
ipOutNoRoutes (12)
MIB, IP Group
ipAddrTable
(ip 20)
ipAddrEntry
(ipAddrTable 1)
ipAdEntReasmMaxSize (5)
ipAdEntAddr (1)
ipAdEntBcastAddr (4)
ipAdEntIfIndex (2)
ipAdEntNetMask
(3)
Entity
ipAddrTable
ipAddrEntry
OID
ip 20
IpAddrTable 1
ipAdEntAddr
IpAddrEntry 1
ipAdEntIfIndex
IpAddrEntry 2
ipAdEntNetMask
IpAddrEntry 3
ipAdEntBcastAddr
ipAdEntReasmMaxSize
IpAddrEntry 4
IpAddrEntry 5
Description (brief)
Table of IP addresses
One of the entries in the IP address
table
The IP address to which this entry's
addressing information pertains
Index value of the entry, same as
ifIndex
Subnet mask for the IP address of
the entry
Broadcast address indicator bit
Largest IP datagram that can be
reassembled on this interface
MIB, IP Group
Contains information used for
Internet routing
 ipRouteTable information is
useful for: configuration
monitoring, controlling the
routing process as well as fault
isolation
ipRouteTable
(ip 21)
ipRouteEntry
ipRouteTable (1)

Entity
ipRouteTable
ipRouteEntry
ipRouteDest
ipRouteIfIndex
ipRouteMetric1
ipRouteMetric2
ipRouteMetric3
ipRouteMetric4
ipRouteNextHop
ipRouteType
ipRouteProto
OID
ip 21
ipRouteTable 1
ipRouteEntry 1
ipRouteEntry 2
ipRouteEntry 3
ipRouteEntry 4
ipRouteEntry 5
ipRouteEntry 6
ipRouteEntry 7
ipRouteEntry 8
ipRouteEntry 9
ipRouteAge
ipRouteMask
ipRouteEntry 10
ipRouteEntry 11
ipRouteMetric5
ipRouteInfo
ipRouteEntry 12
ipRouteEntry 13
ipRouteDest (1)
ipRouteInfo (13)
ipRouteMetric5
ipRouteIfIndex (2)
(12)
ipRouteMetric1 (3)
ipRouteMask 11)
ipRouteMetric2 (4)
ipRouteAge (10)
ipRouteMetric3 (5)
ipRouteProto (9)
ipRouteMetric4 (6)
ipRouteType (8)
ipRouteNextHop (7)
Description (brief)
IP routing table
Route to a particular destination
Destination IP address of this route
Index of interface, same as ifIndex
Primary routing metric for this route
An alternative routing metric for this route
An alternative routing metric for this route
An alternative routing metric for this route
IP address of the next hop
Type of route
Routing mechanism by which this route was
learned
Number of seconds since routing was last updated
Mask to be logically ANDed with the destination
address before comparing with the ipRouteDest
field
An alternative metric for this route
Reference to MIB definition specific to the routing
protocol
MIB, TCP Group
 Contains info. relevant to the implementation/operation of
connection-oriented TCP
Timeout algorithm for retransmission
tcp
(mib-2 6)
tcpOutRsts (15)
tcpRtoAlgorithm (1)
tcpInErrors (14)
tcpRtoMin (2)
tcpConnTable 13)
tcpRtoMax (3)
tcpRetranSegs (12)
tcpMaxConn (4)
tcpOutSegs (11)
tcpActiveOpens (5)
tcpPassiveOpens (6)
tcpInSegs (10)
Minimum value for
tcpAttemptFails (7)
tcpCurrEstab (9)
retransmission timer
tcpEstabResets (8)
# segments
retransmitted
Maximum value for
retransmission timer
Maximum nb of
TCP connections
# segments
received
# segments
sent
MIB, TCP Group
tcpConnTable
(tcp 13)
tcpConnEntry
(1)
tcpConnState (1)
tcpConnLocalAddress (2)
tcpCommRemPort (5)
tcpConnRemAddress(4)
tcpConnLocalPort (3)
Entity
tcpConnTable
tcpconnEntry
OID
tcp 13
TcpConnTable 1
tcpConnState
TcpConnEntry 1
tcpConnLocalAddress TcpConnEntry 2
TcpConnEntry 3
tcpConnLocalPort
tcpConnRemAddress TcpConnEntry 4
TcpConnEntry 5
tcpConnRemPort
Description (brief)
TCP connection table
Information about a particular TCP
connection
State of the TCP connection
Local IP address
Local port number
Remote IP address
Remote port number
SNMP Network Management
 Organization Model
 Communication Model
 Information Model
o Structure of Management Information
(SMI)
o Managed Objects
o Management Information Base (MIB)
 SNMP Administrative Model
 SNMP Protocol Specs
SNMPv1 Administrator Model
SNMP Entities:
 SNMP application entities
o
o
o
Reside in management
stations and network
elements
Manager and agent
Pairing of both entities forms
SNMP community
 Administrative model
defines administrative
relationship between
communicating entities
 Management stations, each
manages all or a subset of
the managed stations in
the configuration
o
 SNMP protocol entities


Communication processes
(PDU handlers)
Peer processes that support
application entities
Subsets may overlap
 Each managed station
controls its local MIB
o
control the use of MIB by
a number of management
stations
SNMPv1 Administrator Model
SNMP Community
It is a relation:
 between one SNMP
agent and a set of
managers
 defines authentication,
access control and
proxy charct.
SNMP Manager
SNMP Manager
SNMP Manager
Authentication Scheme
Authentication Scheme
Authentication Scheme
Authentic Messages
Authentication Scheme
SNMP Agent
 Multiple pairs can belong to the same community
 A community name is a string of octets
 Two application entities in the same community can
communicate with each other
o
This essentially defines a filter module or authentication
scheme between manager and agent
 Security in SNMPv1 is therefore community-based
o
no encryption
SNMPv1 Administrator Model
SNMP Community Profile
only get, and trap are
performed on objects 2,3,4
Operations such as get, set and trap
can be performed on objects 2,3,4
SNMP Agent
READONLY
READWRITE
SNMP Access Mode
not-accessible
read-only
write-only
read-write
Object 1
Object 2
Object 3
Object 4
MIB Access
SNMP MIB View
 Community profile: MIB view + SNMP  Operations on an object is
access mode
o
o
MIB View: a subset of the managed
objects an agent is permitted to
manage/view
A community name is also assigned an
SNMP access mode
 READ ONLY, READ-WRITE
determined by community profile
and the access mode of the
object
o
Total of four access privileges
 Read-only, write-only, readwrite, not-accessible
 Some objects, such as table and
table entry, are non-accessible
SNMPv1 Administrator Model
SNMP Access Policy
Manager
Community
Agent 1
Community Profile 1
Community Profile 2
Agent 2
 Pair of “SNMP community” and “community profile” define SNMP access
policy

Access policy allow a managed agent to give different access privileges to
different managers
 Manager manages network components of communities 1 and 2 via
Agents 1 and 2



Agent 1 has only view of Community Profile 1, e.g. Cisco components
Agent 2 has only view of Community Profile 2, e.g. 3Com components
Manager has total view of both Cisco and 3Com components
SNMPv1 Administrator Model
SNMP Access Policy
Manager 1
(Community 1)
 Manager 1 manages
community 1, manager 2
community 2,and manager
3 (MoM) both communities
1 and 2
Community 1
Agent 1
Community Profile 1
Community Profile 2
Agent 2
 Example: Enterprise
Manager 3
(Community 1, Community 2)
management
Community 2
Agent 3
Community Profile 3
Community Profile 4
Manager 2
(Community 2)
Agent 4
SNMPv1 Administrator Model
 Proxy agent enables non-
SNMP Proxy Access Policy
SNMP community
elements to be managed
by an SNMP manager
 An SNMP MIB is created
to handle the non-SNMP
objects
SNMP Manager
(Community 1)
SNMP
Agent
Proxy Agent
SNMP Community
non-SNMP
Community
SNMP Network Management
 Organization Model
 Communication Model
 Information Model
o Structure of Management Information
(SMI)
o Managed Objects
o Management Information Base (MIB)
 SNMP Administrative Model
 SNMP Protocol Specs
Message Format
version
community
 Protocol entities support
application entities
 Communication between remote
peer processes Message
consists of :
o
o
Version identifier
Community name
 Protocol Data Unit
 Message encapsulated in UDP
datagrams and transmitted
data
 SNMP uses two well-known
ports to operate:


UDP Port 161 - SNMP
Messages
UDP Port 162 - SNMP Trap
Messages
Message Format
version
community
data
 SNMP message format is defined using ASN.1,
encoded for transmission over UDP using BER
Message ::= SEQUENCE {
version
INTEGER {version-1(0)},
community OCTET STRING,
data
PDUs
}
3 different versions:
SNMPv1, SNMPv2, SNMPv3
Message Format-Set/Get PDU
version
community
data
Message ::= SEQUENCE {
version
INTEGER {version-1(0)},
community OCTET STRING,
data
PDUs
}
PDUs::= CHOICE {
get-request
[0] IMPLICIT PDU,
get-next-request [1] IMPLICIT PDU,
get-response
[2] IMPLICIT PDU,
set-request
[3] IMPLICIT PDU,
trap
[4] IMPLICIT Trap-PDU
}
Message Format-Set/Get PDU
PDUtype
requestid
errorstatus
errorindex
PDU ::= SEQUENCE {
request-id
INTEGER,
error-status
INTEGER {
noError
(0),
tooBig
(1),
noSuchName(2),
badValue (3),
readOnly (4),
genErr
(5)
},
error-index
INTEGER,
variable-bindings VarBindList
}
variable-bindings
request-id:
track a message and
indicate loss of a message
(e.g., timeout, etc.)
error-status: indicate the
occurrence of error
error-index: indicate the
occurrence of error (position
in the list of variables)
variable-bindings: grouping of
number of operations in a
single message:
e.g., one request to get all
values and one response listing
all values
Message Format-variable bindings
var-bind 1
name
value
VarBindList
var-bind 2
name
value
var-bind n
...
::= SEQUENCE OF VarBind
VarBind
::= SEQUENCE {
name ObjectName,
value ObjectSyntax
}
ObjectName
::= OBJECT IDENTIFIER
ObjectSyntax ::= CHOICE {
simple
SimpleSyntax,
application-wide ApplicationSyntax
}
name
value
Message Format-variable bindings
SimpleSyntax ::= CHOICE {
number INTEGER,
string OCTET STRING,
object OBJECT IDENTIFIER,
empty NULL
}
ApplicationSyntax::= CHOICE {
address
NetworkAddress,
counter
Counter,
gauge
Gauge,
ticks
TimeTicks,
arbitrary Opaque
}
NetworkAddress::= CHOICE {
internet IpAddress
}
Message Format-Trap PDU
PDUAgent
Generic
Specific
Entreprise
type
Address Trap Type Trap Type
Time
Stamp
variable-bindings
Trap-PDU ::= SEQUENCE {
-Pertain to the system generating
enterprise
OBJECT IDENTIFIER,
the trap (sysObjectID)
agent-addr
NetworkAddress,
-IP address of the objetc
generic-trap
INTEGER {
coldStart
(0),
warmStart
(1),
linkDown
(2),
linkUp
(3),
authenticationFailure(4),
egpNeighborLoss
(5),
enterpriseSpecific
(6)
},
Specific code to identify the
specific-trap
INTEGER,
trap cause…
time-stamp
TimeTicks,
Elapsed time since last re-initialization
variable-bindings VarBindList
}