1 Based on Behzad Akbari Fall 2011 Network Management lectures

 SNMPv1 was developed as a temporary solution to an adoption of OSI.  SNMPv2, released in 1996, was basically major revisions added to SNMP. 2

 Bulk data transfer  Request and receive bulk data using the get-bulk message  Manager-to-manager message  Enhances interoperability and allows for managing large distributed networks  Enhancements to SMI: SMIv2  Module definitions: MODULE-IDENTITY macro  Object definitions: OBJECT-TYPE macro (same as before)  Trap definitions: NOTIFICATION-TYPE macro  Textual conventions: define new data types  Conformance statements  Help customers compare features of various products  Keeps vendors open to their product’s compatibility with SNMP 3

 Row creation and deletion in table  A table can also be expanded by augmenting another table  MIB enhancements  Two new subgroups: security and snmpV2  Transport mappings  UDP remains the preferred transport protocol; however, other protocols can also be used with SNMPv2  Security features, originally to be in SNMPv2 moved to SNMPv3  SNMPv2 is community-based administrative framework 4 SNMPv2 mgmt (2) directory (1) experimental (3) private (4) Internet { } security (5) snmpv2 (6) SNMPv2 Internet Group

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 inform-request  manager-to-manager message  The receiving manager responds with a response message  Enhances interoperability  get-bulk-request  transfer of large data, e.g. retrieval of table data  SNMPv2-trap  Similar to trap messages in SNMPv1 6

 Defines and describe semantics of an information module (info. related to network management)  MODULE-IDENTITY macro defines the module definitions 7

r OBJECT IDENTIFIER, OBJECT-IDENTITY, OBJECT-TYPE m OBJECT IDENTIFIER defines the administrative identification of a node in the MIB m OBJECT-IDENTITY macro (defines info. about OID) assigns an object identifier to a class of managed objects in the MIB (e.g., defining a class of routers!) m OBJECT-TYPE macro defines the type of a managed object (e.g., a specific router type) Focuses on the details of implementation m NOTE: OBJECT-IDENTITY is high level description OBJECT-TYPE details description needed for implementation 8

9 OBJECT-TYPE MACRO ::= BEGIN TYPE NOTATION ::= "SYNTAX" Syntax UnitsPart "MAX-ACCESS" Access "STATUS" Status "DESCRIPTION" Text ReferPart IndexPart DefValPart VALUE NOTATION ::= value(VALUE ObjectName)

10 Access ::= "not-accessible" | "accessible-for-notify" | "read-only" | "read-write" | "read-create" ordered from least to greatest: not-accessible "not-accessible": indicates an assistant object accessible-for-notify "accessible-for-notify": accessible only via a notification read-only "read-only": read only read-write "read-write": read and write, but create does not. read-create "read-create": read, write and create

11 Status ::= "current" | "deprecated" | "obsolete" current “current”: the definition is current and valid. deprecated “deprecated”:indicates an ignored definition, it allows new/continued implementation. obsolete “obsolete”: the definition is ignored and should not be implemented.

12 ReferPart ::= "REFERENCE" Text | empty ipForwardTable OBJECT-TYPE SYNTAX SEQUENCE OF IpForwardEntry MAX-ACCESS not-accessible STATUS obsolete DESCRIPTION "This entity's IP Routing table." REFERENCE "RFC 1213 Section 6.6, The IP Group“ ::= { ipForward 2 }

13 NOTE: A specific instance of routerIsi123 could be identified by its IP address

 Static Tables o Tables completely controlled by the agent. o Access is read-only, and read-write o These are useful when the number of rows corresponds to a fixed attribute (e.g., # physical interfaces)  Dynamic Table o Allows row creation/deletion by a manager o Access includes read-only, read-write, and read-create o A table can be initialized with no rows and expanded as needed  SNMPv2: Augmentation of a table (dependent table) o Adds additional columns to an existing table (base table) o Number of rows is not affected o INDEX of the second table is the same as the first table o One-to-one relation between rows of two tables 14

15 T1.E1.C1.1 table1 (T1) table1Entry (E1) T1.E1.C2.1T1.E1.C3.1 T1.E1.C1.2 T1.E1.C2.2T1.E1.C3.2 T1.E1.C1.3 T1.E1.C2.3T1.E1.C3.3 T1.E1.C1.4 T1.E1.C2.4T.E1.C3.4 table 2 (T2) table2Entry (E2) T2.E2.C4.1T2.E2.C5.1 T2.E2.C4.2T2.E2.C5.2 T2.E2.C4.3T2.E2.C5.3 T2.E2.C4.4T2.E2.C5.4 Index: First columnar object in Table 1 Conceptual rows: 1. T1.E1.C T1.E1.C T1.E1.C T1.E1.C1.4 Table 1 Table 2 Base tableAugmented table Example Columnar object:T2.E2.C4 Index: T1.E1.C1.2 Value: T2.E2.C4.2

16 Example: a vendor can easily specify vendor-specific objects as extensions to standard MIB table. It should be easier for applications to access these objects than if they were defined as new, separate table --Conceptual row extension A clause used to increase the number of columns in a table w/out rewriting the table definition  The resulting table is therefore treated the same way as if it was defined in a single table definition

17  A new feature in SMIv2  2 methods  Create a row and make it active (or available)  Create a row and make it available at a later time   definition of the status of a row Used by manager for row creation/deletion Used by agent to send responses to a manager

18 Row to be created/deleted entry1 status.1 table1 index.1data.1 status.2 status.3 index.2 index.3 data.2 data.3

19  Manager initiates a SetRequest-PDU to create a new row  status = 4, i.e., create and go  Agent interacts with the management entity and successfully create an instance; subsequently a response is transmitted to the manager  status = 1, indicates that the row is active SetRequest ( status.3 = 4, index.3 = 3, data.3 = DefData ) Response ( status.3 = 1, index.3 = 3, data.3 = DefData ) Manager Process Agent Process Managed Entity Create Instance Instance Created

20 Manager Process Agent Process SetRequest ( status.3 = 5, index.3 = 3 ) Create and wait, no default data specified Response ( status.3 = 3, index.3 = 3 ) Agent responds with “notReady” (no default value) GetRequest ( data.3 ) Get the data for the row Response ( data.3 = noSuchInstance) Data value is missing SetRequest ( data.3 = DefData ) Value of data is sent Response ( status.3 = 2 data.3 = DefData ) Agent responds with notInServcie SetRequest ( status.3 = 1 ) Manager requests to activate the row Response ( status.3 = 1 ) Row activated

21 SetRequest ( status.3 = 6 ) Response ( status.3 = 6 ) Manager Process Agent Process Managed Entity Delete Instance Instance Deleted

22  Overall, 8 messages with almost common message format to improve the efficiency and performance  Significant improvement is that trap message has the same format SNMPv2 PDU PDU Type RequestID Error Status Error Index VarBind 1 name VarBind 1 value... VarBind n name VarBind n value Indicate the type of PDU (e.g., Request-PDU, etc) Indicate the status of the error (e.g., noError, tooBig, etc.) identifies the first variable binding in the variable-binding list that caused the error NOTE: SNMPv1 operations (e.g., GET-REQUEST ) are atomic: either all values are returned or none! In SNMPv2: a binding list (with corresponding values) is prepared even if one variable cannot be returned  an (error-status), (error-index) are returned in this case.

23 SNMPv2 Protocol Error index is set to “0” if there is no error; otherwise, it identifies the first variable binding in the variable binding list that caused the error

24  GetBulkRequest enables the retrieval of data in bulk  Uses the same selection principle as GetNexRequest (i.e., next object instance)  Retrieval of multiple rows of data from table (constrained by the max. message size)  Error status field replaced by Non-repeaters  Non-repeaters indicates the number of non repetitive (scalar) field values requested  Error index field replaced by Max repetitions  Max repetitions determine the maximum number of table rows requested to be returned in the response message  NOTE 1: value depends on the size of the SNMP message and buffer size in implementation  NOTE 2: no one to one relationship between the VarBindList of request and response messages SNMPv2 GetBulkRequest PDU PDU Type RequestID Non- Repeaters Max Repetitions VarBind 1 name VarBind 1 value... VarBind n name VarBind n value

25 TZAB 1.1 E T.E.1.1T.E.2.1T.E.3.1 T.E.1.2T.E.2.2T.E.3.2 E T Z A B T.E.1.3T.E.2.3T.E.3.3 T.E.1.4T.E.2.4T.E.3.4

26 GetRequest ( A,B ) GetNextRequest (T.E.1,T.E.2,T.E.3) GetResponse (T.E.1.1,T.E.2.1,T.E.3.1) GetNextRequest (T.E.1.1,T.E.2.1,T.E.3.1) GetResponse (T.E.1.2,T.E.2.2,T.E.3.2) GetResponse (T.E.1.3,T.E.2.3,T.E.3.3) GetNextRequest (T.E.1.3,T.E.2.3,T.E.3.3) GetResponse (T.E.1.4,T.E.2.4,T.E.3.4) GetResponse (T.E.2.1,T.E.3.1,Z) Manager Process Agent Process GetResponse (A,B) GetNextRequest (T.E.1.4,T.E.2.4,T.E.3.4) GetNextRequest (T.E.1.2,T.E.2.2,T.E.3.2)

27 T.E.1.1T.E.2.1T.E.3.1 T.E.1.2T.E.2.2T.E.3.2 E T Z A B T.E.1.3T.E.2.3T.E.3.3 T.E.1.4T.E.2.4T.E.3.4 GetBulkRequest ( 2,3, A,B,T.E.1, T.E.2, T.E.3 ) Response ( A, B, T.E.1.1, T.E.2.1, T.E.3.1 T.E.1.2, T.E.2.2, T.E.3.2 T.E.1.3, T.E.2.3, T.E.3.3 ) GetBulkRequest ( 0,3, T.E.1.3, T.E.2.3, T.E.3.3 ) Response ( T.E.1.4, T.E.2.4, T.E.3.4, Z, "endOfMibView") Manager Process Agent Process 2 non repetitive objects (A, B) 3 repetitive instances Of the columnar object T.E.1, T.E.2, T.E.3 3 more rows Z is next in the lexicographic order

28 MIB SNMPv2 agent MIB SNMPv2 agent MIB SNMPv2 agent MIB SNMPv2 Manager/agent MIB SNMPv2 Manager/agent MIB Management Applications SNMPv2 manager Management server Element manager Agent SNMPv2 Configuration

29  SNMPv2 MIB is not backward compatible with SNMPv1  Compatibility with SNMPv1  2 evolution paths: o Bilingual Manager o Proxy Server  Bilingual Manager expensive in resource and operation SNMPv1 Agents Bilingual Manager SNMPv1 Interpreter SNMPv2 Interpreter Agent Profile SNMPv2 Agents SNMP Bilingual Manager Both interpreters are required!

30 SNMPv1 Agents SNMPv2 Manager Proxy Server SNMPv2 Agents Pass-Through SNMPv2 ManagerSNMPv1 Agent GetNextRequest GetRequest Pass-Through SetRequest Set: 1. non-repeaters = 0 2. max-repetitions = 0 GetBulkRequest Pass-Through Exception: For 'tooBig' error, contents of variable-bindings field removed. Response Prepend VarBind: 1. sysUpTime.0 2. snmpTrapOID.0 SNMPv2-Trap GetRequest GetResponse GetNextRequest SetRequest GetNextRequest Trap SNMP v2-v1 Proxy Server

31 SNMPv2 MIB