1. SNMP Management: Organization and Information Model
In the Name of the Most High
SNMP Management: Organization and Information Model by
Behzad Akbari
Fall 2011

2. Overview SNMP is the most widely used network management protocol
When we say SNMP management, we are really referring to Internet management.
SNMP management model:
Organization Model
Relationship between network element, agent, and manager
Hierarchical architecture
Information Model
Uses ASN.1 syntax
SMI (Structure of Management Information
MIB ( Management Information Base)
Communication Model
Transfer syntax
SNMP over TCP/IP
Communication services addressed by messages
Security framework community-based model

3. Managed LAN
NMS on subnet manages the router and the hubs on subnet across the backbone network
Figure 4.1 A Managed LAN Network

4. Managed Hubs: System Information
Information obtained querying the hubs
Data truly reflects what is stored in the hub
Title: System Information:
Name or IP Address:
System Name:
System Description: 3Com LinkBuilder FMS, SW version:3.02
System Contact:
System Location:
System Object ID: .iso.org.dod.internet.private.enterprises
System Up Time: ( ) 286 days, 12:03:24.37
Title: System Information:
Name or IP Address:
System Name:
System Description: 3Com LinkBuilder FMS, SW version:3.12
System Contact:
System Location:
System Object ID: .iso.org.dod.internet.private.enterprises
System Up Time: ( ) 364 days, 12:55:51.82

5. Managed Router: System Information
Title: System Information: router1.gatech.edu
Name or IP Address:
System Name: router1.gatech.edu
System Description: Cisco Internetwork Operating System Software
: IOS (tm) 7000 Software (C7000-JS-M), Version
: 11.2(6),RELEASE SOFTWARE (ge1)
: Copyright (c) by Cisco Systems, Inc.
: Compiled Tue 06-May-97 19:11 by kuong
System Contact:
System Location:
System Object ID:
iso.org.dod.internet.private.enterprises.cisco.ciscoProducts.cisco 7000
System Up Time: ( ) 36 days, 11:21:57.95

6. Managed Hub: Port Addresses
Information acquired by the NMS on hub interfaces
Index refers to the interface on the hub
Link address is the MAC address
The second row data is a serial link

7. Managed Router: Port Addresses
Information acquired by NMS on the router interfaces
Index refers to the interface on the router
LEC is the LAN emulation card
Ethernet 2/0 interface refers to the interface card 2 and port 0 in that card

8. Internet Management History
1970s: Advanced Research Project Agency Network
(ARPANET) comes up with Internet control Message Protocol (ICMP)
Internet Engineering Task Force (IETF)
1990 SNMPv1
1995 SNMPv2
1998 SNMPv3
Internet documents:
Request for Comments (RFC)
IETF STD Internet Standard
FYI For your information

9. SNMP Related RFCs
Figure 4.4 SNMP Document Evolution

10. 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

11. 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
Object
agent
Managed Objects
Managers may have restricted
access to managed objects

12. 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
Object
agent
Managed Objects
RMON Probe
Managers may have restricted
access to managed objects
3-tier architecture

13. Organization Model
Proxy server converts non-SNMP data from non-SNMP objects to SNMP compatible objects and messages
MIB
SNMP Manager
Proxy Server
Managed
Object
agent
Wireless LAN
Managed Objects
unmanaged Objects

14. System Overview Manages objects SNMP messages
SNMP Manager
Application
Get-Response
Get-Request
GetNext-Request
Set-Request
Trap
UDP IP
DLC
PHY
SNMP Agent
SNMP agent
Physical Medium
Manage-
ment
Data
Network or
Internet
Manages objects
SNMP messages
Figure 4.9 SNMP Network Management Architecture

15. SNMP System Architecture
Management
Station
Network Elements (NEs)
Host
Router
Manager
Agent
Agent
SNMP
Network
Management
Protocol
SNMP
SNMP
. . .
UDP
UDP
UDP IP IP IP DL DL DL
SNMP
Network

16. SNMP Services Manager Agent(s) Four Services Five SNMP Messages
Get, Set, GetNext Request
Get Response
Trap
Manager
Agent(s)
Four Services
Get, Set, GetNext, Trap
Five SNMP Messages
GetRequest, SetRequest, GetNextRequest, GetResponse, Trap

17. SNMP Services Get GetNext Set Trap Get Request Get Response
Manager
Agent
GetNext Request
Set Request
Trap Request
Get
GetNext
Set
Trap

18. SNMP Services (cont.) Get Request: Get-Next Request: Set Request:
Retrieve the values of objects in the MIB of an agent.
Get-Next Request:
Retrieve the values of the next objects in the MIB of an agent.
Set Request:
Update the values of objects in the MIB of an agent.
Trap Request
Report extraordinary events to the manager.

19. Information Model
Structure of Management Information (SMI) (RFC 1155, RFC 1212)
Managed Object
Scalar
Aggregate or tabular object
Management Information Base (RFC 1213)

20. Managed Object
Object Type
Object Instance

21. Managed Object: Multiple Instances
Object Type
Object Instance

22. Object Name
Object is uniquely defined by
DESCRIPTOR
OBJECT IDENTIFIER

23. Internet Subnodes directory OBJECT IDENTIFIER ::= {internet 1}
mgmt OBJECT IDENTIFIER ::= {internet 2}
experimental OBJECT IDENTIFIER ::= {internet 3}
private OBJECT IDENTIFIER ::= {internet 4}

24. root 2 1
ccitt
iso
joint-iso-ccitt 3 2 1
std
reg
authority
org
member
body 6
dod 1
internet 1 4 2 3
directory
mgmt
experimental
private 1 1
MIB II
MIB II
enterprises
enterprises
system 1
interface 2
interface at 3 IP 4
ICMP 5
TCP 6
UDP 7
EGP 8
Trans. 10
SNMP 11

25. Private MIB Example http://www.iana.org/ Enterprise Number

26. SNMP ASN.1 Data Type

27. Primitive Data Types subtype: INTEGER (0..255)
OCTET STRING (SIZE )
OCTET STRING (SIZE 8)

28. Enumerated
Special case of INTEGER data type

29. Defined or Application Data Type

30. Constructor or Structured Data Type: SEQUENCE
List Marker
SEQUENCE { <type1>, <type2>,…, <typeN> }
IpAddrEntry ::=
SEQUENCE {
ipAdEntAddr IpAddress,
ipAdEntIfIndex INTEGER,
ipAdEntNetMask IpAddress,
ipAdEntBcastAddr INTEGER,
ipAdEntReasmMaxSize INTEGER ( ) }

31. Constructor or Structured Data Type: SEQUENCE OF
SEQUENCE OF <entry>
where <entry> is a list constructor
ipAddrTable OBJECT-TYPE
SYNTAX SEQUENCE OF IpAddrEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"The table of addressing information relevant to
this entity's IP addresses."
::= { ip 20 }

32. Example: IP Address Table
Each row (table entry) is a sequence: IpAddrEntry.
The ipAddrTable table is a sequence of rows (entries), i.e. a sequence of ipAddrEntry.

33. Encoding
Basic Encoding Rules (BER)
- Type, Length, and Value (TLV)

34. SNMP Data Types and Tags
Type Tag
OBJECT IDENTIFIER UNIVERSAL 6
SEQUENCE UNIVERSAL 16
IpAddress APPLICATION 0
Counter APPLICATION 1
Gauge APPLICATION 2
TimeTicks APPLICATION 3
Opaque APPLICATION 4

35. Managed Object: Structure

36. SMIv1, SMIv2 SMIv1: SMIv2: SMI (RFC 1155) Concise MIB (RFC 1212)
Trap-Type (RFC 1215)
SMIv2:
SMIv2 (RFC 2578)
Textual Conventions (RFC 2579)
Conformance Statements (RFC 2580)

37. Object-Type Macro (RFC 1155)
OBJECT-TYPE MACRO ::= BEGIN
TYPE NOTATION ::= "SYNTAX" type (TYPE ObjectSyntax)
“ACCESS" Access
"STATUS" Status
VALUE NOTATION ::= value (VALUE ObjectName)
Access ::= "read-only" | "read-write“ | "write-only | "not-accessible"
Status ::= "mandatory” | "optional“ | "obsolete"
END

38. OBJECT-TYPE MACRO (RFC1212)
BEGIN
TYPE NOTATION ::=
"SYNTAX" type(ObjectSyntax)
"ACCESS" Access
"STATUS" Status
DescrPart
ReferPart
IndexPart
DefValPart
VALUE NOTATION ::= value (VALUE ObjectName)       
ObjectName ::= OBJECT IDENTIFIER

39. OBJECT-TYPE Example sysLocation OBJECT-TYPE
SYNTAX DisplayString (SIZE (0..255))
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The physical location of this node (e.g.,
`telephone closet, 3rd floor')."
::= { system 6 }
DisplayString ::=
OCTET STRING (SIZE (0..255))

40. "SYNTAX" type(ObjectSyntax)
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 }

41. ApplicationSyntax 0 .. 232-1 NetworkAddress ::= CHOICE {
internet IpAddress }
IpAddress ::=
[APPLICATION 0] IMPLICIT OCTET STRING (SIZE (4))
Counter ::=
[APPLICATION 1] IMPLICIT INTEGER ( )
Gauge ::=
[APPLICATION 2] IMPLICIT INTEGER ( )
TimeTicks ::=
[APPLICATION 3] IMPLICIT INTEGER ( ) Opaque ::=
[APPLICATION 4] IMPLICIT OCTET STRING
Back to OBJECT TYPE

42. "ACCESS" Access "STATUS" Status
Access ::= "read-only"
| "read-write"
| "write-only"
| "not-accessible
Status ::= "mandatory"
| "optional"
| "obsolete"
| "deprecated"
Back to OBJECT TYPE

43. DescrPart DescrPart ::=
DescrPart ::=
"DESCRIPTION" value (description DisplayString)
| empty
ReferPart ::=
"REFERENCE" value (reference DisplayString)
ReferPart 
Back to OBJECT TYPE

44. DefValPart DefValPart ::=
"DEFVAL" "{" value (defvalue ObjectSyntax) "}"
| empty
Example:
ifNumber OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DEFVAL 1
DESCRIPTION
"The number of network interfaces (regardless of
their current state) present on this system.“
::= { interfaces 1 }
Back to OBJECT TYPE

45. IndexPart IndexPart ::= "INDEX" "{" IndexTypes "}" IndexTypes ::=
value (indexobject ObjectName)
| type (indextype)
IndexSyntax ::=
CHOICE {
number
INTEGER (0..MAX),
string
OCTET STRING,
object
OBJECT IDENTIFIER,
address
NetworkAddress,
ipAddress
IpAddress }

46. instance-identifier (INDEX)
integer-valued
3  3
string-valued, fixed-length strings
‘ c2e’H 
string-valued, variable-length strings
“IIS Admin” 
object identifier-valued 
NetworkAddress-valued 
IpAddress-valued 

47. Index - variable-length string
svSvcTable OBJECT-TYPE
SYNTAX SEQUENCE OF SvSvcEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"A list of service entries describing
network services installed on this
server.“
::= { server 3 }
svSvcEntry OBJECT-TYPE
SYNTAX SvSvcEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"The names of the network services
installed on this server."
INDEX { svSvcName }
::= { svSvcTable 1 }
Back to OBJECT TYPE

48. OBJECT-TYPE Example dot1dBasePortEntry OBJECT-TYPE
SYNTAX Dot1dBasePortEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"A list of information for each port of the bridge."
REFERENCE
"IEEE 802.1D-1990: Section 6.4.2, 6.6.1"
INDEX { dot1dBasePort }
::= { dot1dBasePortTable 1 }

49. Aggregate Object A group of objects Also called tabular objects
Can be represented by a table with
Columns of objects
Rows of instances
Table of Objects
List of Objects
Objects

50. Aggregate M.O. Macro: Table Object
ipAddrTable OBJECT-TYPE
SYNTAX SEQUENCE OF IpAddrEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"The table of addressing information
relevant to this entity's IP addresses."
::= {ip 20}

51. Aggregate M.O. Macro: Entry Object
ipAddrEntry OBJECT-TYPE
SYNTAX IpAddrEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"The addressing information for one of this entity's IP addresses."
INDEX { ipAdEntAddr }
::= { ipAddrTable 1 }
ipAddrEntry: OBJECT-TYPE
IpaddrEntry: SYNTAX

52. Aggregate M.O. Macro: Entry Object
IpAddrEntry ::=
SEQUENCE {
ipAdEntAddr IpAddress,
ipAdEntIfIndex INTEGER,
ipAdEntNetMask IpAddress,
ipAdEntBcastAddr INTEGER,
ipAdEntReasmMaxSize INTEGER ( ) }

53. Aggregate M.O. Macro: Columnar Objects
ipAdEntAddr OBJECT-TYPE
SYNTAX IpAddress
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The IP address to which this entry's
addressing information pertains.”
::= { ipAddrEntry 1 }

54. Tabular Representation of Aggregate Object

55. Tabular Representation of Aggregate Object

56. Multiple Instances of Aggregate Managed Object

57. Example

58. Identification of Managed Objects
Use Object Identifier (OID)
OID = Object Type OID . Instance Identifier
Object Type OID:
Each Object type has a unique OID
Instance Identifier:
Identify instances of object type
E.g .mib-2.interface.ifTable.ifEntry.ifDescr.2

59. Two Kinds of Managed Objects
Type-Specific Objects:
sysDescr OBJECT-TYPE
SYNTAX DisplayString (SIZE(0..255))
::= {system 1}
OID: mib-2.system.1.0
Columnar Objects
OID:
mib-2.interface.ifTable.ifEntry.ifDescr.2
mib-2.interface.ifTable.ifEntry.ifDescr.6
mib-2.interface.ifTable.ifEntry.ifType.2
mib-2.interface.ifTable.ifEntry.ifType.6

60. Columnar Objects IfEntry ::= SEQUENCE { ifTable OBJECT-TYPE
ifIndex INTEGER,
ifDescr DisplayString,
ifType INTEGER, … }
ifTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfEntry …
::= { interface 2 }
ifEntry OBJECT-TYPE
SYNTAX IfEntry …
INDEX {ifIndex }
::= { ifTable 1}
ifDescr OBJECT-TYPE
SYNTAX DisplayString (SIZE(0..255))
ACCESS read-only
STATUS madatory
...
::= {ifEntry 2}

61. Columnar Objects
.ifTable.ifEntry.1 ( ) ifTable.ifEntry.2 ( )
.ifTable.ifEntry.3 ( )
ifIndex ifDescr ifType le
llc lo le

62. Index in MIB II ifEntry {ifIndex} atEntry {atNetIfIndex, atNetAddress}
ipAddrEntry {ipAdEntAddr }
ipRouteEntry {ipRouteDest}
ipNetToMediaEntry {ipNetToMediaIfIndex,
ipNetToMediaNetAddress}
tcpConnEntry
{tcpConnLocalAddress, tcpConnLocalPort,
tcpConnRemoteAddress, tcpConnRemotePort}
udpEntry {udpLocalAddress, udpLocalPort}
egpNeighEntry {egpNeighAddr}

63. Index Example To get the state of the TCP connection:
: ===> : 80
Use snmp_get_req. to get the “tcpConnState” of the tcpConnTable in MIB II.
tcpConnState ==>

64. tcpConnTable

65. 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

66. MIB, RFC1213
mgmt
(2)
directory
(1)
experimental
(3)
private
(4)
Internet
{ }
mib-2
Internet MIB-II Group
system (1)
interfaces (2)
at (3)
ip (4)
icmp (5)
snmp (11)
transmission (10)
cmot (9)
egp (8)
udp (7)
tcp (6)
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)
<module name> DEFINITIONS ::= BEGIN
<imports>
<definitions>
END

67. MIB, RFC1213 -- groups in MIB-II RFC1213-MIB DEFINITIONS ::= BEGIN
system OBJECT IDENTIFIER ::= { mib-2 1}
interfaces 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}
snmp OBJECT IDENTIFIER ::= { mib-2 11 } .
END
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 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)
PhysAddress ::=
-- 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.

68. MIB, System Group sysServices (7) sysLocation (6) sysDescr (1) system
-- 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 "A textual description of the entity. ……."
::= { system 1 }
sysServices (7)
sysLocation (6)
sysDescr (1)
system
(mib-2 1)
sysObjectId
(2)
sysUpTime (3)
sysName (5)
sysContact (4)
sysObjectID OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
ACCESS read-only
STATUS mandatory
DESCRIPTION "The vendor's authoritative identification of the network management subsystem contained in the entity."
::= { system 2 }
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 reinitialized."
::= { system 3 }

69. 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!
Programmed by vendor of objects during manufacturing time

70. MIB, Interface Group
ifTable
(2)
ifNumber
(1)
interfaces
(mib-2 2)
ifEntry
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)
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
interfaces OBJECT IDENTIFIER ::= { mib-2 2 }

71. MIB, Interface Group ifNumber OBJECT-TYPE SYNTAX INTEGER
ifTable
(2)
ifNumber
(1)
interfaces
(mib-2 2)
ifEntry
ifNumber OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION "The number of network interfaces (regardless of their current state) present on this system."
::= { interfaces 1 }
ifEntry OBJECT-TYPE
SYNTAX IfEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION "An interface entry containing objects at the sub-network layer and below for a particular interface."
INDEX { ifIndex }
::= { ifTable 1 }
ifTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION "A list of interface entries. The number of entries is given by the value of ifNumber."
::= { interfaces 2 }
IfEntry ::= SEQUENCE {ifIndex INTEGER, ifDescr DisplayString, ifType INTEGER,
ifMtu INTEGER, ifSpeed Gauge, ifPhysAddress PhysAddress, ifAdminStatus INTEGER,
ifOperStatus INTEGER, ifLastChange TimeTicks, ifInOctets Counter, ……}

72. MIB, Interface Group
ifTable
(2)
ifNumber
(1)
interfaces
(mib-2 2)
ifEntry
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)
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!

73. MIB, IP Group
ipRoutingDiscards (23) ip
(mib-2 4)
ipForwarding (1)
ipDefaultTTL (2)
ipInReceives (3)
ipInHdrErrors (4)
ipInAddrErrors (5)
ipForwDatagrams (6)
ipInUnknownProtos (7)
ipInDiscards (8)
ipInDelivers (9)
ipOutRequests(10)
ipNetToMediaTable (22)
ipRouteTable (21)
ipAddrTable (20)
ipFragCreates (19)
ipFragFails (18)
ipFragOKs (17)
ipReasmFails (16)
ipReasmOKs (15)
ipReasmReqds (14)
ipOutDiscards (11)
ipReasmTimeout (13)
ipOutNoRoutes (12)
Contains information relevant to the implementation and operation of IP at a node
Routers periodically execute routing algorithms and update routing tables
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

74. MIB, IP Group Gateway or router TTL in IP header Total # packets
ipRoutingDiscards (23) ip
(mib-2 4)
ipForwarding (1)
ipDefaultTTL (2)
ipInReceives (3)
ipInHdrErrors (4)
ipInAddrErrors (5)
ipForwDatagrams (6)
ipInUnknownProtos (7)
ipInDiscards (8)
ipInDelivers (9)
ipOutRequests(10)
ipNetToMediaTable (22)
ipRouteTable (21)
ipAddrTable (20)
ipFragCreates (19)
ipFragFails (18)
ipFragOKs (17)
ipReasmFails (16)
ipReasmOKs (15)
ipReasmReqds (14)
ipOutDiscards (11)
ipReasmTimeout (13)
ipOutNoRoutes (12)
Gateway or router
TTL in IP header
Total # packets
received from interfaces
# of discarded datagrams
due to header errors

75. MIB, IP Group ipAddrTable (ip 20) ipAddrEntry (ipAddrTable 1)
ipAdEntAddr (1)
ipAddrEntry
(ipAddrTable 1)
ipAdEntReasmMaxSize (5)
ipAdEntBcastAddr (4)
ipAddrTable
(ip 20)
ipAdEntIfIndex (2)
ipAdEntNetMask
(3)

76. MIB, IP Group Contains information used for Internet routing
ipRouteEntry
ipRouteTable (1)
ipRouteDest
(1)
ipRouteIfIndex (2)
ipRouteMetric1 (3)
ipRouteMetric2 (4)
ipRouteMetric3 (5)
ipRouteInfo (13)
ipRouteMetric5
(12)
ipRouteMask 11)
ipRouteAge (10)
ipRouteProto (9)
ipRouteMetric4 (6)
ipRouteType (8)
ipRouteNextHop (7)
ipRouteTable
(ip 21)
Contains information used for Internet routing
ipRouteTable information is useful for: configuration monitoring, controlling the routing process as well as fault isolation

77. MIB, TCP Group
Contains info. relevant to the implementation/operation of connection-oriented TCP
tcp
(mib-2 6)
tcpRtoAlgorithm
(1)
tcpRtoMin (2)
tcpRtoMax (3)
tcpMaxConn (4)
tcpActiveOpens (5)
tcpOutRsts (15)
tcpInErrors (14)
tcpConnTable 13)
tcpRetranSegs (12)
tcpOutSegs (11)
tcpPassiveOpens (6)
tcpInSegs (10)
tcpCurrEstab (9)
tcpAttemptFails (7)
tcpEstabResets (8)
Timeout algorithm for retransmission
Minimum value for
retransmission timer
# segments
retransmitted
Maximum value for
retransmission timer
# segments
received
# segments
sent
Maximum nb of
TCP connections

78. MIB, TCP Group tcpConnEntry (1) tcpConnState (1)
tcpConnLocalAddress (2)
tcpCommRemPort (5)
tcpConnRemAddress(4)
tcpConnLocalPort (3)
tcpConnTable
(tcp 13)