All MIBs › CISCO-VLAN-BRIDGING-MIB › cvbStpForwardingMap
cvbStpForwardingMap
Module: CISCO-VLAN-BRIDGING-MIB
OID (symbolic): CISCO-VLAN-BRIDGING-MIB::cvbStpForwardingMap
OID (numeric): 1.3.6.1.4.1.9.9.56.1.1.1.1.2
Node type: OBJECT-TYPE
Type: OCTET STRING
Access: read-only
Description: An indication of which ports are forwarding by spanning tree for the specified VLAN. The octet string contains one bit per port on the bridge for the specified VLAN.
Each octet within the value of this object specifies a set of eight ports, with the first octet specifying ports 1 through 8, the second octet specifying ports 9 through 16, etc. Within each octet, the most significant bit represents the lowest numbered port, and the least significant bit represents the highest numbered port.
The bit value interpretation is related to RFC 1493 dot1dStpPortState values is as follows: 1 = forwarding 0 = disabled, blocking, listening, learning, broken, or nonexistent
What is cvbStpForwardingMap?
This read-only OCTET STRING (0-128 bytes) indicates which ports are forwarding under Spanning Tree for a specific VLAN, with one bit per port, the first octet covering ports 1-8, the second 9-16, and so on, most significant bit representing the lowest port number in each octet. An admin cares because this map is a direct, per-VLAN snapshot of the bridge's actual STP forwarding topology, useful for confirming which ports are actively passing traffic versus blocked. For example, an operator diagnosing a VLAN with intermittent connectivity would decode this bit map to check whether an expected uplink port is actually shown as forwarding rather than blocked by STP.
Examples
Walk all instances (SNMPv2c):
snmpwalk -v2c -c public <target> 1.3.6.1.4.1.9.9.56.1.1.1.1.2 snmpwalk -v2c -c public <target> CISCO-VLAN-BRIDGING-MIB::cvbStpForwardingMap
Get a specific instance (index 1):
snmpget -v2c -c public <target> 1.3.6.1.4.1.9.9.56.1.1.1.1.2.1 snmpget -v2c -c public <target> CISCO-VLAN-BRIDGING-MIB::cvbStpForwardingMap.1
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OID Breakdown
Upper-level ancestors (8 from the standard OID tree / other modules)
| Numeric OID | Name | Module |
|---|---|---|
| 1 | iso | LANART-AGENT |
| 1.3 | org | AirPair-MIB |
| 1.3.6 | dod | AirPair-MIB |
| 1.3.6.1 | internet | AirPair-MIB |
| 1.3.6.1.4 | private | AirPair-MIB |
| 1.3.6.1.4.1 | enterprises | AirPair-MIB |
| 1.3.6.1.4.1.9 | cisco | CAT2600-MIB |
| 1.3.6.1.4.1.9.9 | ciscoMgmt | CISCO-SMI |
| Numeric OID | Name | Module |
|---|---|---|
| 1.3.6.1.4.1.9.9.56 | ciscoVlanBridgingMIB | CISCO-VLAN-BRIDGING-MIB |
| 1.3.6.1.4.1.9.9.56.1 | ciscoVlanBridgingMIBObjects | CISCO-VLAN-BRIDGING-MIB |
| 1.3.6.1.4.1.9.9.56.1.1 | cvbStp | CISCO-VLAN-BRIDGING-MIB |
| 1.3.6.1.4.1.9.9.56.1.1.1 | cvbStpTable | CISCO-VLAN-BRIDGING-MIB |
| 1.3.6.1.4.1.9.9.56.1.1.1.1 | cvbStpEntry | CISCO-VLAN-BRIDGING-MIB |
| 1.3.6.1.4.1.9.9.56.1.1.1.1.2 | cvbStpForwardingMap | CISCO-VLAN-BRIDGING-MIB |