Alcatel-Lucent 장비와 연동시 RSTP 호환성 문제
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Alcatel-Lucent 장비와 Spanning-Tree 연동시 주의사항
Alcatel-Lucent 장비는 Spanning-Tree Mode가 2가지 있습니다.
1. FLAT MODE : 모든 VLAN에 해하여 1개의 STP or RSTP가 동작하는 표준 호환 MODE 입니다.
2. 1x1 MODE : 설정된 각 VLAN 마다 STP or RSTP가 동작하는 MODE 이며, 표준 STP or RSTP와 호환되지 않습니다.
이 때문에 Alcatel-Lucent와 Spanning-Tree 연동시 반드시 해당 MODE를 확인하시기 바랍니다.
이 부분이 호환되지 않는 경우 Loop 발생현상이 나타날 수 있으며, 연결된 장비에서 보면 ARP Table에서 ARP가 나타났다가 사라졌다 하는 현상도 발생할 수 있습니다.
이 경우 Network이 느려지는 현상이 발생하며, 하단에 연결된 Port 등을 제거하여도 동일한 현상이 나타납니다.
현장에서 많은 시행착오를 겪을 수 있으며, Alcatel-Lucent 장비와 연동시 불특정하게 Loop 이 발생하는 현상이나 Network이 느려지는 현상이 있다면 반드시 확인하시기 바랍니다.
다음은 Alcatel-Lucent 장비에서 설정을 변경하는 내용입니다.
bridge mode
Selects a flat Spanning Tree or 1x1 Spanning Tree operating mode for the switch. These modes are exclusive;
however, it is not necessary to reboot the switch when changing modes.
bridge mode {flat | 1x1}
Syntax Definitions
flat One Spanning Tree instance per switch.
1x1 One Spanning Tree instance for each VLAN configured on a switch.
Defaults
By default, the bridge mode for the switch is set to 1x1 Spanning Tree.
Platforms Supported
OmniSwitch 6400, 6800, 6850, 6855, 9000, 9000E
Usage Guidelines
• The Multiple Spanning Tree Protocol (MSTP), as defined in the IEEE 802.1Q 2005 standard, is only supported on switches operating in the flat Spanning Tree mode.
• If standard STP or RSTP is used when the switch is running in the flat mode, a single STP instance is applied across all VLANs. For example, if a port belonging to VLAN 10 and a port belonging to VLAN 20 both connect to the same switch, then STP will block one of these ports.
• If MSTP is used when the switch is running in the flat mode, a single STP instance is applied to each Multiple Spanning Tree Instance (MSTI). Each MSTI represents a set of VLANs.
• Flat Spanning Tree mode supports fixed (untagged) and 802.1Q tagged ports in each VLAN. However, Bridge Protocol Data Units (BPDUs) are always untagged.
• If 1x1 mode is selected, a single Spanning Tree instance is enabled for each VLAN configured on the switch. For example, if there are five VLANs configured on the switch, then there are five separate Spanning Tree instances. In essence, a VLAN is a virtual bridge in that it will have its own bridge ID and configurable STP parameters, such as protocol, priority, hello time, max age, and forward delay.
• When operating in 1x1 mode, 802.1Q tagged ports participate in an 802.1Q Spanning Tree instance that allows the Spanning Tree to extend across tagged VLANs. As a result, a tagged port may participate in more than one Spanning Tree instance; one for each VLAN that the port carries.
• If a VLAN contains both fixed and tagged ports and the switch is operating in 1x1 Spanning Tree mode, then a hybrid of the two Spanning Tree instances (single and 802.1Q) is applied. If a VLAN appears as a tag on a port, then the BPDU for that VLAN are also tagged. However, if a VLAN appears as the configured default VLAN for the port, then BPDU are not tagged and the single Spanning Tree instance applies.
• Regardless of which mode the switch is running in, it is possible to administratively disable the Spanning Tree status for an individual VLAN (see Chapter 21, “VLAN Management Commands”). Note that active ports associated with such a VLAN are excluded from any Spanning Tree calculations and will remain in a forwarding state.
Examples
-> bridge mode flat
-> bridge mode 1x1
Release History
Release 6.1; command was introduced.
Related Commands
bridge protocol Selects the Spanning Tree protocol for the specified instance.
bridge bpdu-switching Enables the switching of Spanning Tree BPDU on a VLAN that has Spanning Tree disabled.
show spantree Displays VLAN Spanning Tree parameter values.
MIB Objects
vStpTable
vStpNumber
vStpMode
bridge protocol
Configures the Spanning Tree protocol for the flat mode Common and Internal Spanning Tree (CIST)
instance or for an individual VLAN instance if the switch is running in the 1x1 mode.
bridge [instance] protocol {stp | rstp | mstp}
Syntax Definitions
instance The flat mode CIST instance (1) or an existing 1x1 mode VLAN ID
instance number (bridge 1–4094).
stp IEEE 802.1D standard Spanning Tree Algorithm and Protocol.
rstp IEEE 802.1W Rapid Spanning Tree Protocol.
mstp IEEE 802.1Q 2005 Multiple Spanning Tree Protocol.
Defaults
RSTP is the default protocol for the flat mode CIST instance and for the 1x1 mode VLAN instance.
Platforms Supported
OmniSwitch 6400, 6800, 6850, 6855, 9000, 9000E
Usage Guidelines
• Specifying an instance number with this command when the switch is running in the 1x1 SpanningvvTree mode implies a VLAN ID and configures the protocol for the associated VLAN instance.
• To configure the protocol for the flat mode CIST instance when the switch is running in either the flat or 1x1 mode, do not specify an instance number. The CIST is the instance configured by default with this command.
• If the switch is running in the flat mode and STP or RSTP is the active protocol, entering 1 to specify the CIST instance is optional. If MSTP is the active protocol, however, entering 1 for the instance number is not accepted.
• Note that selecting MSTP is only an option for the flat mode CIST instance and is required to configure Multiple Spanning Tree Instances (MSTI).
• MSTP is only active when the switch is operating in the flat Spanning Tree mode. STP and RSTP are active when the switch is operating in either the flat or 1x1 Spanning Tree mode.
• Deleting all existing MSTIs is required before changing the protocol from MSTP to STP or RSTP.
• Note that when changing the protocol to/from MSTP, the bridge priority and port path cost values for the flat mode CIST instance are reset to their default values. However, if the path cost mode was set to 32-bit prior to the protocol change, the path cost is not reset to its default value. See the bridge path cost mode command page for more information.
Examples
-> bridge mode flat
-> bridge protocol mstp
-> bridge protocol rstp
-> bridge protocol stp
-> bridge mode 1x1
-> bridge 10 protocol rstp
-> bridge 200 protocol stp
-> bridge protocol mstp
-> bridge protocol rstp
-> bridge protocol stp
Release History
Release 6.1; command was introduced.
Release 6.1.2; default protocol changed to RSTP.
Related Commands
bridge mode Selects the Spanning Tree operating mode (flat or 1x1) for the switch.
bridge cist protocol Explicit command for changing the Spanning Tree protocol for the flat mode instance.
bridge 1x1 protocol Explicit command or changing the Spanning Tree protocol for a VLAN instance.
MIB Objects
vStpInsTable
vStpInsNumber
vStpInsMode
vStpInsProtocolSpecification