LevelOne GEP-5070 Manual - Page 26

CHAPTER 1 | Introduction Description of Software Features be ignored and will not be written to the address table. Static addresses can be used to provide network security by restricting access for a known host to a specific port. IEEE 802.1D BRIDGE The switch supports IEEE 802.1D transparent bridging. The address table facilitates data switching by learning addresses, and then filtering or forwarding traffic based on this information. The address table supports up to 16K addresses. STORE-AND-FORWARD SWITCHING The switch copies each frame into its memory before forwarding them to another port. This ensures that all frames are a standard Ethernet size and have been verified for accuracy with the cyclic redundancy check (CRC). This prevents bad frames from entering the network and wasting bandwidth. To avoid dropping frames on congested ports, the switch provides 8 MB for frame buffering. This buffer can queue packets awaiting transmission on congested networks. SPANNING TREE ALGORITHM The switch supports these spanning tree protocols: ◆ Spanning Tree Protocol (STP, IEEE 802.1D) - Supported by using the STP backward compatible mode provided by RSTP. STP provides loop detection. When there are multiple physical paths between segments, this protocol will choose a single path and disable all others to ensure that only one route exists between any two stations on the network. This prevents the creation of network loops. However, if the chosen path should fail for any reason, an alternate path will be activated to maintain the connection. ◆ Rapid Spanning Tree Protocol (RSTP, IEEE 802.1w) - This protocol reduces the convergence time for network topology changes to about 3 to 5 seconds, compared to 30 seconds or more for the older IEEE 802.1D STP standard. It is intended as a complete replacement for STP, but can still interoperate with switches running the older standard by automatically reconfiguring ports to STP-compliant mode if they detect STP protocol messages from attached devices. ◆ Multiple Spanning Tree Protocol (MSTP, IEEE 802.1s) - This protocol is a direct extension of RSTP. It can provide an independent spanning tree for different VLANs. It simplifies network management, provides for even faster convergence than RSTP by limiting the size of each region, and prevents VLAN members from being segmented from the rest of the group (as sometimes occurs with IEEE 802.1D STP). - 26 -