CTRON-Q-BRIDGE-MIB-EXT

MIB Reference — IPNetwork Monitor · Updated October 05, 2026

All MIBs › CTRON-Q-BRIDGE-MIB-EXT

Organization: Enterasys Networks, Inc.

Last Updated: 2007-02-16

Category: VLAN and Bridging, Vendor: Cabletron/Enterasys

Description: Extends IEEE 802.1Q bridge MIB with Cabletron-specific VLAN configuration and per-port VLAN attributes.

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What Is CTRON-Q-BRIDGE-MIB-EXT?

CTRON-Q-BRIDGE-MIB-EXT is a Cabletron (Enterasys) enterprise MIB that extends the standard IEEE 802.1Q Q-BRIDGE-MIB (RFC 2674) with Cabletron-specific per-port and per-VLAN attributes for switches supporting 802.1Q VLAN tagging. It exposes configuration objects covering per-port VLAN forwarding behavior (default forward mode, tagged-frame discard, TCI replacement) and per-VLAN dynamic egress port sets, both current and forbidden. It is primarily a configuration/software-state MIB: an operator uses it to confirm a port's VLAN tagging and forwarding policy actually match intent, and to see which ports have been dynamically added to (or explicitly forbidden from) a VLAN's egress set, rather than to monitor physical hardware sensors. As its module description states, it explicitly builds on and extends the IEEE 802.1Q standard and the IETF Q-BRIDGE-MIB, so it must be interpreted together with the base standard MIB's VLAN and bridge port tables. It is deployed on Cabletron/Enterasys managed Ethernet switches that support IEEE 802.1Q VLAN tagging in mixed vendor/standards-based network environments. Network engineers evaluating or troubleshooting this functionality can download the CTRON-Q-BRIDGE-MIB-EXT file directly to load it into their MIB browser.

IPNetwork Monitor allows you to monitor SNMP objects defined in CTRON-Q-BRIDGE-MIB-EXT. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

  • Cabletron/Enterasys managed Ethernet switch (IEEE 802.1Q VLAN capable)

Monitoring Examples

An administrator would poll ctDot1qPortVlanExtTable entries for a given port to check ctDot1qPortDefaultForwardMode, ctDot1qPortDiscardTagged, and ctDot1qPortReplaceTCI, confirming the port is set to discard or accept tagged frames as configured. Walking ctDot1qVlanCurrentExtTable/ctDot1qVlanCurrentEntryExt alongside ctDot1qVlanForbidEgressPorts for a VLAN reveals which ports are actually forwarding that VLAN's traffic versus explicitly barred from it. If ctDot1qVlanDynamicEgressTable shows a port dynamically added to a VLAN's egress set unexpectedly, that would flag an unintended VLAN leak via dynamic learning.

What Can Be Monitored

  • per-port default VLAN forward mode
  • tagged-frame discard setting per port
  • TCI replacement setting per port
  • VLAN dynamic egress port membership
  • VLAN forbidden egress ports
Imported Objects

From BRIDGE-MIB

dot1dBasePortOBJECT-TYPE
dot1dBasePortEntryOBJECT-TYPE

From CTRON-MIB-NAMES

ctVlanExtOBJECT-IDENTITY

From P-BRIDGE-MIB

EnabledStatus

From Q-BRIDGE-MIB

PortList
VlanIndex
dot1qFdbIdOBJECT-TYPE
dot1qTpFdbAddressOBJECT-TYPE
dot1qVlanCurrentEntryOBJECT-TYPE
dot1qVlanIndexOBJECT-TYPE

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-SMI

MODULE-IDENTITY
OBJECT-TYPE

From SNMPv2-TC

TruthValue
OIDs

RFC description

IEEE 802.1Q VLAN and Q-BRIDGE configuration extensions for Enterasys and Cabletron switches.

Start monitoring Cabletron/Enterasys managed Ethernet switch (802.1Q VLAN extension) with a free 30-day trial of IPNetwork Monitor. Import MIBs, browse SNMP OIDs, create custom SNMP monitors, configure alerts, and monitor any SNMP-enabled network device from a single console.

Download CTRON-Q-BRIDGE-MIB-EXT