protocols. A unidirectional link occurs whenever traffic sent by the local device is received by the neighbor but traffic from the neighbor is not received by the local device. If one of the fiber strands in a pair is disconnected, as long as auto negotiation is active, the link does not stay up. In this case, the logical link is undetermined, and UDLD does not take any action. If both fibers are working normally from a Layer 1 perspective, UDLD at Layer 2 determines whether those fibers are connected correctly and whether traffic is flowing bi-directional between the correct neighbors. This check cannot be performed by auto negotiation because auto negotiation operates at Layer 1. You can enable UDLD globally for all Fiber-optic interfaces, or per interface for any media type.
An EtherChannel consists of individual Fast Ethernet or Gigabit Ethernet links bundled into a single logical link. The EtherChannel provides full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 8 Gbps (Gigabit EtherChannel) between your switch and another switch or host.
You create an EtherChannel for Layer 2 interfaces differently from Layer 3 interfaces. Both configurations involve logical interfaces.
With Layer 3 interfaces, you manually create the logical interface by using the 搃nterface port-channel?global configuration command.
With Layer 2 interfaces, the logical interface is dynamically created.
With both Layer 3 and 2 interfaces, you manually assign an interface to the EtherChannel by using the channel-group interface configuration command. This command binds the physical and logical ports together.
The Port Aggregation Protocol (PAgP) facilitates the automatic creation of EtherChannels by exchanging packets between Ethernet interfaces. By using PAgP, the
精品推荐