User manual TRENDNET TE100-S55

[. . . ] ProXpress TM Multifunction Switch/Router Model TE100-S55 for connecting 10Base-T, 100Base-TX, 100Base-FX and ISDN links User's Guide First Edition - June 1, 1996 Trademarks Copyright 1996 TRENDware All rights reserved, contents may be revised without prior notice. TRENDnet is a registered trademark of TRENDware Ethernet is a trademark of Xerox Corporation. FCC warning This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. [. . . ] This parameter enables all bridges in the network to establish a Root Bridge. A change to the Bridge Priority may cause the network to re-establish a new Root Bridge. A high Bridge Priority increases the chance for a bridge to be selected as the Root Bridge (the smaller the number, the higher the priority). Root Path Cost: From each bridge, Root Path Cost is the total Path Cost of reaching the Root Bridge from a Designated Bridge. Designated Bridge: From each LAN segment, the bridge that has the lowest Root Path Cost to the Root Bridge becomes the Designated Bridge. In case all bridges on a segment have the same Root Path Cost, the bridge with the lowest Bridge Identifier becomes the Designated Bridge. 1 The bridge MAC address is only used to decide the Root Bridge when there are 2 or more bridges with the same Bridge Priority. 29 AT THE PORT LEVEL Designated Port: This is the port on each Designated Bridge that forwards data packets for the attached LAN segment. Root Port: Each bridge has a Root Port that has the lowest Path Cost to the Root Bridge. In case there are several ports with the same Path Cost, the one with the lowest Port Identifier (Port Priority + pre-assigned Port ID) becomes the Root Port1. Port Priority: This is a user changeable parameter for each port on the bridge. In conjunction with a pre-set port ID, this parameter determines the Root Port of a Bridge. The 100Mb segments will have auto-assigned Path Cost of 10, while the 10Mb segments will have auto-assigned Path Cost of 100. 1 2 In a bridge, a port is Blocked, if it is not a Root or a Designated Port. However, it is fixed by the TE100-S55 implementation. 30 TIMERS Max. Should a Bridge fail to receive an identifier packet from its Root Bridge within this time limit, it assumes that the Root Bridge has failed. Should a Bridge be assigned as a Root Bridge, the Hello Time setting will be used as the interval to send out identifier packets to notify other Bridges of its existence. This is the delay time that each port on a Bridge waits in the Listening state before changing its Blocking state to the Forwarding state. 31 ILLUSTRATION OF STA A simple illustration of three Bridges (or TE100-S55) connected in a loop is depicted in Figure 3-2. In this example, you can anticipate some major network problems if the STA assistance is not applied. For instance, if Bridge 1 broadcasts a packet to Bridge 2, Bridge 2 will broadcast it to Bridge 3, and Bridge 3 will broadcast it to Bridge 1. . . and so on. The broadcast packet will be passed indefinitely in a loop, causing a serious network failure. To alleviate network loop problems, STA can be applied as shown in Figure Chapter 3 -3. In this example, STA breaks the loop by blocking the connection between Bridge 1 and 2. The decision to block a particular connection is based on the STA calculation of the most current Bridge and Port settings. Now, if Bridge 1 broadcasts a packet to Bridge 3, then Bridge 3 will broadcast it to Bridge 2 and the broadcast will end there. [. . . ] 27, 29, 30, 45 Port Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Port Physical setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25, 45 Port Priority. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28, 30, 39 Port State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24, 25, 35, 44, 45 Port Status LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ]