Definitions of Managed Objects for Routing Bridges (RBridges)
Extracted elements (25)
Separate confidence levels (0–255) are configurable for native-learned, decap-learned, and statically configured MAC entries. Static entries default to 255, giving operators fine-grained control over which source can displace an existing FDB entry.
The RBridge MIB is designed to interoperate with either the IETF Bridge MIBs (BRIDGE-MIB, Q-BRIDGE-MIB) or the IEEE 802.1 Bridge MIBs (IEEE8021-BRIDGE-MIB, IEEE8021-Q-BRIDGE-MIB), because both sets have been widely deployed. Per RFC 4663, IETF transferred Bridge MIBs to IEEE 802.1.
The rbridgeFdb subtree is a deliberate superset of the BRIDGE-MIB and Q-BRIDGE-MIB FDB subtrees, adding the egress nickname and ESADI-source status fields needed for TRILL forwarding that have no equivalent in 802.1D/Q management.
For TRILL (RFC 6325), IS-IS is constrained to a single Level 1 area with fixed area address zero, used for TRILL only with no IP address advertisement. ISIS-MIB tables for IP reachability, multiple areas, multiple levels, or multiple protocols will be empty for TRILL instances.
rbridgeBasePortStpWiringCloset must be set to the same Bridge ID value on all RBridge ports participating in the Wiring Closet topology solution (RFC 6325 Appendix A.3.3); a non-zero value signals that the solution is active on that port.
When both RBridge and IS-IS IP router functions run on the same device, multiple IS-IS MIB instances are distinguished using SNMPv3 contexts or SNMPv1 communities.
Full compliance requires implementing nine mandatory object groups: rbridgeBaseGroup, rbridgeBaseNicknameGroup, rbridgeBasePortGroup, rbridgeFdbGroup, rbridgeFibGroup, rbridgeVlanGroup, rbridgeDtreeGroup, rbridgeTrillGroup, and rbridgeNotificationGroup. Port counters, ESADI, and snooping groups are optional.
IF-MIB port identification elements MUST be implemented to allow cross-referencing between per-port parameters and higher-level physical device functions, per RFC 2863 Section 4 requirements for media-specific MIB adjuncts.
The value of all configurable MIB objects (read-write and read-create) MUST be retained across re-initializations of the management system. This applies to ForwardDelay, multipath enables, port flags, nickname configuration, ESADI parameters, and MTU settings.
RbridgeAddress is a 6-byte OCTET STRING textual convention (display-hint '1x:') representing the MAC address of an RBridge port, which may match the RBridge IS-IS SystemID.
rbridgeBaseNicknameTable manages up to rbridgeBaseNicknameNumber (1..256) nicknames per RBridge. Each entry carries a hold-priority (0..255, default 192 for configured entries with MSB set), distribution-tree-root priority (default 32768), and type (static or dynamic).
rbridgeBasePortTable provides per-port configuration: disable bit, trunk port (end-station service disable), access port (TRILL traffic disable except Hellos), P2P Hello mode, inhibition time (default 30 s), MAC learning disable, and desired/actual Designated VLAN.
rbridgeDtreeTable tracks distribution trees computed by the RBridge, providing tree number, root nickname, and ingress eligibility flag. Campus-wide scalars report active tree count, this RBridge's maximum computable trees, and desired usage count.
rbridgeEsadiTable manages per-VLAN ESADI (End-Station Address Distribution Information) instances with enable flag, confidence level (default 16), DRB election priority (0..127), current DRB MAC address, and holding time.
rbridgeMultiFibTable maps multi-destination distribution tree nicknames to the set of egress ports (PortList) for frame flooding, subject to further pruning based on other forwarding information.
RbridgeNickname is a 16-bit TRILL identifier (Unsigned32 0..65471) that abbreviates a RBridge's 48-bit IS-IS System ID. Value 0 means unspecified; 0xFFC0–0xFFFE are reserved for future allocation; 0xFFFF is permanently reserved.
rbridgePortCounterTable provides per-port 64-bit TRILL in/out frame counts (rbridgePortTrillInFrames, rbridgePortTrillOutFrames) and 32-bit drop counters for RPF check failures, hop-count-exceeded drops, and unsupported-option drops.
rbridgeSnoopingPortTable and rbridgeSnoopingAddrTable track IP multicast snooping: router type (ipv4, ipv6, ipv4v6) per port/VLAN, and listener port sets per multicast address. Only global IPv4 (4-byte) and IPv6 (16-byte) address types are required.
rbridgeTrillNbrTable indexes TRILL neighbors by MAC address, reporting the negotiated MTU for IS-IS communication and a boolean flag indicating whether the neighbor's MTU is below the campus minimum of 1470 bytes.
rbridgeUniFdbTable is the unicast forwarding database, indexed by FDB-ID and MAC address, providing egress RBridge nickname, confidence level (0..255), and entry status (other, invalid, learned, self, mgmt, esadi). It extends BRIDGE-MIB and Q-BRIDGE-MIB FDB tables with TRILL-specific fields.
rbridgeUniFibTable is the unicast Forwarding Information Base, indexed by destination nickname, egress port, and next-hop nickname, providing hop count. Multiple entries per nickname exist when ECMP paths are available.
Two SNMP notifications are defined: rbridgeBaseNewDrb (sent when the RBridge becomes the new Designated RBridge, after the Topology Change Timer expires) and rbridgeBaseTopologyChange (sent on VLAN-x designated forwarder transitions, unless a NewDrb notification covers the same event).
IANA assigned OID mib-2 214 as the root of the RBRIDGE-MIB module (rbridgeMIB), published as RFC 6850. Subtrees are: rbridgeNotifications (0), rbridgeObjects (1), rbridgeConformance (2).
The RBRIDGE-MIB contains numerous read-write and read-create objects that can alter forwarding behavior (port disable, VLAN forwarder, multipath, learning suppression). SNMP access should be restricted using SNMPv3 authentication and privacy. A read-only compliance variant (rbridgeReadOnlyCompliance) is provided for monitoring-only deployments that cannot allow configuration via SNMP.
RBridge port state (rbridgeBasePortState) has five states: uninhibited(1), portInhibited(2), vlanInhibited(3), disabled(4), broken(5). portInhibited/vlanInhibited are triggered by spanning tree root changes or conflicting forwarder information; disabled by operator; broken by detected malfunction.