BLADE OS™ Application Guide HP GbE2c Ethernet Blade Switch for c-Class BladeSystem Version 5.1 Advanced Functionality Software
Table Of Contents
- Contents
- Figures
- Tables
- Preface
- Part 1: Basic Switching
- Accessing the Switch
- The Management Network
- Local Management Using the Console Port
- The Command Line Interface
- Remote Management Access
- Client IP Address Agents
- Securing Access to the Switch
- Setting Allowable Source IP Address Ranges
- RADIUS Authentication and Authorization
- TACACS+ Authentication
- LDAP Authentication and Authorization
- Secure Shell and Secure Copy
- Configuring SSH/SCP Features on the Switch
- Configuring the SCP Administrator Password
- Using SSH and SCP Client Commands
- SSH and SCP Encryption of Management Messages
- Generating RSA Host and Server Keys for SSH Access
- SSH/SCP Integration with Radius Authentication
- SSH/SCP Integration with TACACS+ Authentication
- End User Access Control
- Ports and Trunking
- Port-Based Network Access Control
- VLANs
- Spanning Tree Protocol
- RSTP and MSTP
- Link Layer Discovery Protocol
- Quality of Service
- Accessing the Switch
- Part 2: IP Routing
- Basic IP Routing
- Routing Information Protocol
- IGMP
- OSPF
- OSPF Overview
- OSPF Implementation in BLADE OS
- OSPF Configuration Examples
- Remote Monitoring
- Part 3: High Availability Fundamentals
- High Availability
- Layer 2 Failover
- Server Link Failure Detection
- VRRP Overview
- Failover Methods
- BLADE OS Extensions to VRRP
- Virtual Router Deployment Considerations
- High Availability Configurations
- High Availability
- Part 4: Appendices
- Index
BLADE OS 5.1 Application Guide
110 Chapter 5: Spanning Tree Protocol BMD00113, September 2009
The relationship between port, trunk groups, VLANs, and STP Groups is shown in Table 11.
Note – The sequence used by STP for listening, learning, and forwarding or blocking, is lengthy
and delays may occur. You can use Port Fast Forwarding (/cfg/port <x>/fastfwd/ena) to
permit a port that participates in STP to bypass the Listening and Learning states and enter directly
into the Forwarding state. While in the Forwarding state, the port listens to the BPDUs to learn if
there is a loop and, if dictated by normal STP behavior (following priorities, and so on), the port
transitions into the Blocking state. This feature permits the GbE2c to interoperate well within Rapid
Spanning Tree networks.
Bridge Protocol Data Units (BPDUs)
BDPU Overview
To create a Spanning Tree, the switch generates a configuration Bridge Protocol Data Unit (BPDU),
which it then forwards out of its ports. All switches in the Layer 2 network participating in STP
gather information about other switches in the network through an exchange of BPDUs.
A BPDU is a 64-byte packet that is sent out at a configurable interval, which is typically set for two
seconds. The BPDU is used to establish a path, much like a “hello” packet in IP routing. BPDUs
contain information about the transmitting bridge and its ports, including bridge and MAC
addresses, bridge priority, port priority, and path cost. If the ports are tagged, each port sends out a
special BPDU containing the tagged information.
The generic action of a switch on receiving a BPDU is to compare the received BPDU to its own
BPDU that it will transmit. If the received BPDU is better than its own BPDU, it will replace its
BPDU with the received BPDU. Then, the switch adds its own bridge ID number and increments
the path cost of the BPDU. The switch uses this information to block any necessary ports.
Table 11 Ports, Trunk Groups, and VLANs
Switch Element Belongs To
Port Trunk group, or one or more VLANs
Trunk group One or more VLANs
VLAN (non-default) One Spanning Tree Group