Simple Network Management Protocol (SNMP) over IEEE 802 Networks
obsoletes
- rfc-1089 — SNMP over Ethernet
updates
- rfc-3417 — Transport Mappings for the Simple Network Management Protocol (SNMP)
Extracted elements (15)
SNMP over IEEE 802 is an optional transport mapping intended for managing simple devices directly over an 802 LAN without IP. The motivation was identified in applications like the Two-Port MAC Relay (IEEE 802.1 project P802.1aj), which require management at the link layer.
Using the SNMP over IEEE 802 transport mapping inherently restricts messages to a single logical IEEE 802 LAN, bridged LAN, or VLAN. Only a single SNMP engine can be addressed on a given IEEE 802 network interface, requiring command generators and notification receivers to share a single transport endpoint.
RFC 4789 obsoletes RFC 1089 (the original SNMP over Ethernet specification) and updates RFC 3417 (SNMP transport mappings) by adding the IEEE 802 transport domain as an additional optional transport mapping.
The snmpIeee802Domain OID constant can be assigned to TDomain objects in MIB modules such as SNMP-TARGET-MIB, NOTIFICATION-LOG-MIB, and ENTITY-MIB. When used, the corresponding TAddress value must conform to the MacAddress textual convention from SNMPv2-TC.
In IEEE 802 LANs that use LLC as the means of link layer protocol identification, such as IEEE 802.11 Wireless LANs, the SNAP encapsulation method described in subclause 10.5 of [IEEE802] MUST be used.
It is RECOMMENDED that implementations be capable of accepting SNMP messages of up to 1472 octets in size, and implementation of larger values is encouraged whenever possible.
When an SNMP entity uses this transport mapping, it MUST be capable of accepting SNMP messages up to and including 484 octets in size. It is RECOMMENDED that implementations be capable of accepting messages of up to 1472 octets in size.
When serialized SNMP messages are sent in IEEE 802.3 frames (and other IEEE 802 MAC frame types that can natively represent Ethernet type values), an Ethernet type field value of 33100 (hexadecimal 814C) MUST be used as the link layer protocol identifier.
Serialized SNMP messages are sent in IEEE 802.3 frames with an Ethernet type field of 33100 (hexadecimal 814C), identifying SNMP as the link-layer protocol.
The SNMP-IEEE802-TM-MIB module (OID: snmpModules 21) defines the SNMP over IEEE 802 transport mapping. It introduces snmpIeee802Domain as an OBJECT-IDENTITY constant.
The snmpIeee802Domain OBJECT-IDENTITY (OID: snmpDomains 6) defines the SNMP over IEEE 802 networks transport domain. The corresponding transport address is of type MacAddress as defined in the SNMPv2-TC module (RFC 2579).
IANA assigned OID 6 under snmpDomains (1.3.6.1.6.1.6) for snmpIeee802Domain (SNMP over IEEE 802), and assigned OID snmpModules 21 for the SNMP-IEEE802-TM-MIB module. A new IANA registry for OIDs under snmpDomains was established as part of this assignment.
It is the customer/user responsibility to ensure that the SNMP entity giving access to a MIB is properly configured to grant access only to principals with legitimate rights to GET or SET managed objects.
SNMPv1 and SNMPv2c messages are not considered secure. Implementors are recommended to use SNMPv3 with the User-based Security Model (USM, RFC 3414) and the View-based Access Control Model (VACM, RFC 3415) to provide authentication and access control.
SNMP messages are serialized per RFC 3417 Section 8 and placed in the data portion of an IEEE LAN MAC frame. The IEEE 802.3 frame carries a 6-byte destination Ethernet address, 6-byte source Ethernet address, a 2-byte Ethertype field (0x814C), followed by the variable-length SNMP message payload.