Discovery | SNMP GetBulk VS SNMP WalkSummary<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } This purpose of this Knowledge Base article is to provide more insight into SNMP Probe boolean parameter use_getbulk to help our Customer's better evaluate if, when, and where to change this parameter. From ServiceNow Product Documentation on SNMP Probe Parameters. Parameter Name: use_getbulk Enables the use of SNMP GETBULK requests to retrieve tabular data from SNMP devices instead of using multiple SNMP GETNEXT requests.For tabular data, GETBULK is more efficient. Regardless of the request type, certain devices may not return any results when they are busy with other tasks. This parameter is used to configure at the probe level. GETBULK can also be set for an individual MID Server or globally for all MID servers. Settings are listed in the order of precedence: SNMP probe parameterMID Server configuration parameterMID Server properties In summary, Discovery uses SNMP GetBulk when use_getbulk is set to true, and SNMP Walk when it is set to false. Below is a summary on SNMP GetBulk and SNMP Walk in general for most SNMP applications or tools. SNMP GetBulk and Walk are both methods used to retrieve information from SNMP-enabled devices, but they differ in their underlying mechanism and efficiency, especially when dealing with large datasets. SNMP Walk (using GetNext requests): An SNMP walk operation, often performed by tools like snmpwalk, essentially performs a series of GetNext requests.The GetNext request retrieves the next lexicographically ordered object identifier (OID) and its corresponding value after a specified OID.To "walk" an entire MIB subtree or table, the manager repeatedly sends GetNext requests, each time requesting the next OID until it reaches the end of the desired subtree or table.This process involves multiple round trips between the manager and the agent, with each GetNext request and its response being a separate transaction. SNMP GetBulk: GetBulk is an SNMPv2c and SNMPv3 operation designed for more efficient retrieval of large amounts of data, particularly tables or long lists of variables.Instead of requesting one OID at a time, a single GetBulk request can specify a starting OID and parameters like max-repetitions and non-repeaters.The max-repetitions parameter tells the agent how many OIDs to retrieve in a single response for repeating variables (like table entries).The non-repeaters parameter specifies how many initial OIDs in the request should be treated as non-repeating variables (like scalar values).The agent then attempts to return as many requested OIDs as possible in a single response, significantly reducing the number of network round trips. Key Differences and Advantages of GetBulk: Efficiency: GetBulk is significantly more efficient than walk for retrieving large datasets because it minimizes the number of request/response exchanges, reducing network latency and bandwidth usage. Performance: This efficiency translates to faster data retrieval, especially in high-latency environments or when dealing with large tables. Reduced Agent Load: By consolidating multiple requests into one, GetBulk can also reduce the processing load on the SNMP agent. Compatibility: GetBulk is only available in SNMPv2c and SNMPv3. SNMPv1 devices do not support GetBulk and will require the traditional walk method using GetNext. In summary, while both walk and GetBulk achieve the goal of retrieving multiple SNMP variables, GetBulk offers a more optimized and efficient approach for bulk data retrieval. Related Links<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } ServiceNow Product Documentation Links SNMP Probe Parameters