Protocol Independent Multicast (PIM) Bootstrap Router MIB
Extracted elements (25)
The BSR-specific MIB tables were separated from the earlier PIM MIB (RFC 5060) into this standalone module to provide a focused, independently deployable MIB for managing the BSR mechanism without requiring the full PIM MIB.
Object definitions for C-RP advertisement interval, holdtime, C-BSR priority election, and RP priority semantics directly reference RFC 5059 (Bootstrap Router mechanism for PIM). Implementations must align MIB object behavior with the protocol semantics defined there.
The MIB uses textual conventions from INET-ADDRESS-MIB (RFC 4001), including InetAddressType, InetAddress, InetAddressPrefixLength, and InetZoneIndex, enabling dual IPv4/IPv6 address handling throughout all four tables.
Zone-scope information for pimBsrCandidateBSRZoneIndex and pimBsrElectedBSRZoneIndex must be correlated with the ipMcastZoneTable defined in the IP Multicast MIB (RFC 5132). The value zero is reserved as a default-zone request and is not a valid index value in this MIB.
Deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, SNMPv3 with cryptographic security enabled is RECOMMENDED, with access restricted to principals with legitimate rights.
Implementations of this MIB module MUST include the pimBsrObjectGroup as a mandatory conformance group. The pimBsrDiagnosticsGroup (notifications) is optional.
It is RECOMMENDED that implementers consider the security features provided by the SNMPv3 framework, including full support for SNMPv3 cryptographic mechanisms for authentication and privacy.
pimBsrCandidateBSRHashMaskLength (Unsigned32 0..128) controls the hash mask length advertised in Bootstrap messages. It defaults to 30 for IPv4/IPv4z address types and to 126 for IPv6/IPv6z address types.
pimBsrCandidateRPHoldtime (Unsigned32 0..65535 seconds, default 150) represents the validity period of the C-RP advertisement entry. A value of zero is only valid when the C-RP is shutting down.
The PIM-BSR-MIB module contains four conceptual tables: the Candidate-RP Table (C-RP configurations), the Elected BSR RP-Set Table (Group-to-RP mappings on the E-BSR), the Candidate-BSR Table (C-BSR configurations), and the Elected-BSR Table (per-zone elected BSR state).
The pimBsrCandidateBSREntry includes address type and address, priority (Unsigned32 0..255, higher=higher priority, default 0), hash mask length (default 30 for IPv4, 126 for IPv6), elected-BSR flag (read-only), bootstrap timer (read-only, zero when not elected), row status, and storage type.
The pimBsrCandidateBSRTable contains one row per zone for which the local router is configured as a Candidate-BSR. It is indexed by pimBsrCandidateBSRZoneIndex (InetZoneIndex, range 1..4294967295; zero is invalid).
The pimBsrCandidateBSRWinElection SNMP notification is generated when a C-BSR wins the BSR election, i.e., when pimBsrCandidateBSRElectedBSR transitions to TRUE. It carries pimBsrCandidateBSRElectedBSR as its varbind.
The pimBsrCandidateRPEntry includes fields for RP address, group prefix, BIDIR-PIM flag (pimBsrCandidateRPBidir), advertisement timer, priority (Unsigned32 0..255, default 192), advertisement interval (default 60s), holdtime (default 150s), row status, and storage type.
The pimBsrCandidateRPGroupAddress index field is significant only up to pimBsrCandidateRPGroupPrefixLength bits; remaining bits must be zero. Non-zero remainder bits would identify an entirely different table entry.
The pimBsrCandidateRPTable lists multicast group address prefixes for which the local router advertises itself as a Candidate-RP. It is indexed by address type, RP address, group address, and group prefix length.
The pimBsrElectedBSRLostElection SNMP notification is generated when the current E-BSR loses election to a new C-BSR, i.e., when pimBsrCandidateBSRElectedBSR transitions to FALSE. It carries the outgoing E-BSR's address type, address, and priority.
The pimBsrElectedBSRRPSetEntry is indexed by address type, group address, group prefix length, and RP address. It exposes RP priority (0..255, higher=lower priority), holdtime, expiry time, and a BIDIR-PIM flag; all fields are read-only.
The pimBsrElectedBSRRPSetTable exists only on an elected BSR and lists Group-to-RP mappings received via C-RP advertisements or local configuration. The E-BSR applies local policy to select which entries to include in Bootstrap messages.
The pimBsrElectedBSRTable contains one read-only row per zone for which there is an elected BSR, exposing address type, address, priority, hash mask length, and expiry time (time until the E-BSR is declared down).
IANA assigned the OID { mib-2 172 } to pimBsrMIB, recorded in the SMI Numbers registry under the descriptor 'pimBsrMIB'.
A new or modified Candidate-BSR with a manipulated high priority (bsrCandidateBSRPriority) can usurp the Elected BSR role, preventing and disrupting multicast services across the zone.
A new or modified Candidate-RP with a manipulated low priority (bsrCandidateRPPriority) can force routers to select it as the RP for a particular group prefix, enabling traffic interception or service disruption.
Read access (GET/NOTIFY) to objects such as pimBsrElectedBSRAddress, pimBsrElectedBSRPriority, and related fields reveals the multicast network topology (elected BSR, candidate BSRs, candidate RPs), which can be used to prepare Denial-of-Service attacks. These values should be protected and possibly encrypted in transit.
SNMP versions prior to SNMPv3 provide no access control independent of network-level security (e.g., IPsec). Even on a secure network, there is no per-principal control over who may read, write, create, or delete MIB objects.