交换技术STPModule5-5冗余的拓扑.ppt

合肥Logsure网络技术有限公司 冗余的拓扑 广播帧 广播风暴 重复帧 MAC地址表的不稳定 利用 STP 解决环路 Spanning-Tree 操作 STP 根桥的选举 Spanning-Tree 端口状态 Uplinkfast / Backbonefast PortFast Configuring and Verifying PortFast BPDU护卫 / 过滤器 Spanning-Tree Operation Example Spanning-Tree Path Cost Spanning-Tree Recalculation Per VLAN Spanning Tree Plus PVST+ 扩展的 桥 ID Rapid Spanning Tree Protocol Default Spanning-Tree Configuration Cisco 交换机三种类型的STPs: PVST+ PVRST+ MSTP 默认情况下在Cisco交换机上使用PVST+ : 每个VLAN有一个独立的STP 所有VLAN可以使用同一个交换机做根 但不等做负载均衡 PVRST+ 配置指南 Enable PVRST+. 指定和配置交换机为根桥. 指定和配置另一个交换机为备份的根桥. 验证配置. PVRST+ 执行命令 验证 PVRST+ Configuring the Root and Secondary Bridges Configuring the Root and Secondary Bridges: SwitchA Configuring the Root and Secondary Bridges: SwitchB Summary 冗余的交换网络拓扑包含多交换机和以太通道组 冗余的网络产生环路问题，例如广播风暴. 使用STP生成无环路的网络拓扑. 原始的STP被加强为PVST+和RSTP. Layer 3 of 3 Emphasize: Layer 2 has no TTL mechanism to stop looping frames. Layer 2 of 2 Layer 2 of 2 Emphasize: A looped topology is often desired to provide redundancy, but looped traffic is undesirable. The Spanning-Tree protocol was originally designed for bridges. Today, it is also applied to LAN switches and routers operating as a bridge. Spanning-Tree protocol ensures that all bridged segments are reachable but any points where loops occur will be blocked. Emphasize: The three general rules when dealing with STP are as follows: 1. One root bridge per network. The root is the bridge with the lowest bridge ID. All the ports on the root bridge are designated ports (forwarding). 2. For every non-root bridge, there is a root port (forwarding). The root port is the port with the lowest accumulated path cost to the root bridge. 3. For every segment, there is only one designated port. The designated port forwards traffic for the segment. The designated port has the lowest accumulated path cost to the root bridge. Emphasize: By default, the switch with the lowest MAC address will be the root bridge. Note: The Catalyst switches support an instance of spanning