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Station Management (SMT) is the layer of the FDDI protocol that is responsible for monitoring network operation, detecting errors, and isolating faults. SMT initializes nodes, inserts nodes to the ring, and removes nodes from the ring.
Each FDDI node participates in ring management by exchanging SMT information (using SMT frames) with other nodes on the ring. There are different types of SMT frames, each used for a specific purpose. For example, SMT Status Report Frames are sent wherever there is a change in the ring configuration. Similarly, SMT Neighbor Information Frames are used by FDDI nodes to determine or announce their neighbors. These SMT NIF frames contain the address of the sender, the address of its nearest upstream neighbor, and additional information about the node itself. By capturing and analyzing these frames, Ring Monitor can build a map of the ring. You use Ring Monitor to configure, display, and print FDDI statistics. In this chapter, you will learn how you use Ring Monitor to look at your FDDI network.
Ring Monitor builds a ring map by collecting SMT Neighbor Information Frames (SMT-NIFs). These SMT frames are exchanged periodically in intervals of 2 to 30 seconds. When the FDDI ring monitor application is launched, the FDDI NSP starts collecting the SMT-NIFs and building the FDDI ring map.
However, the ring map is complete only when the probe has been able to collect SMT-NIFs from all the nodes on the ring. Until that happens, a partial ring map is displayed, and the Ring Map Status in the Ring Monitor is displayed as Incomplete. When the ring map is complete (typically, 10 to 60 seconds), the Ring Map Status is displayed as Complete. Note that the ring map is rebuilt whenever there is a change in the ring configuration.
Although the time taken to build the ring map is typically less than 60 seconds, under certain conditions the ring map may take longer to be completed or may never be completed at all. If the ring is overloaded, the nodes take longer (several minutes) to exchange SMT-NIFs. Therefore, the time to build the ring map increases as well. If there is a node on the ring that has stopped or there is a node that does not exchange SMT-NIFs, the ring map will never be completed. This happens if the node has hung, is too busy to participate in the SMT-Neighbor Protocol, or does not conform to the SMT-NIF protocol.
In this section are the procedures you will use to monitor your FDDI network with Ring Monitor.
Use the following procedure to launch Ring Monitor from the TrafficDirector main window and display the Ring Monitor Ring Station List for the FDDI agent you select.
Step 1 Log in to the network management station where TrafficDirector is installed, and run the TrafficDirector application.
Step 2 Select an FDDI agent from those shown in the Agents[All] list, or select the agent group containing the FDDI agent you want to monitor. If the agent you want is not listed, you may need to add it. To do so, see the "Working with Agents, Agent Groups, and Switches" chapter.
Step 3 Click the Ring Monitor icon, or select Application>Ring Monitor from the menu bar.
Step 4 The Ring Monitor main window--the Ring Station List (Figure 10-1)--is displayed for the selected agent. From this main window, you can now work with Ring Monitor in a variety of ways, described by procedures in this chapter.
The Ring Station List window consists of an upper list and a lower list. The upper list shows information about each of the nodes on the ring and contains the following information:
| Ring Order | The order of this station in the ring. |
| Station | The name of the station. |
| Address | The address of the station. |
| Last Enter Time | The last time the station entered the ring. |
| Last Exit Time | The last time the station exited the ring. |
| RIns | Ring insertions. The number of times a station has been inserted into the ring. |
| Status | Whether a station is active (currently in the ring) or inactive (not currently in the ring). |
The lower list shows information about the specific node highlighted in the upper list. It contains the following information:
| Station Address | The name and address of the highlighted station. |
| Nearest Upstream Neighbor Address | The address of the nearest active upstream neighbor (NAUN) of the highlighted station. |
| Node Class | FDDI nodes can be classified into stations and concentrators. The primary purpose of a station is to transmit and receive information. Concentrators are like hubs, providing facilities to connect additional nodes. Some types of nodes can have zero, one, or two MAC addresses. For example, a dual-attachment node with two MAC addresses is able to simultaneously receive and transmit frames on both the logical rings. This is not possible with a dual-attachment node that has only one MAC.
Node class indicates the node type and can be any one of the following: · Single-attachment station (SAS). · Single-MAC-Dual-attachment station (SM-DAS). · Dual-MAC-Dual-attachment station (DM-DAS). · MAC-less-Single-attachment concentrator (SAC). · Single-MAC-Single-attachment concentrator (SAC). · Single-MAC-Dual-attachment concentrator (DAC). · Dual-MAC-Dual-attachment concentrator (DAC). |
| Topology State | The topology state of the node indicates whether it is correctly connected on the ring. The states are indicated as follows:
· Normal. The node is correctly connected. · Twisted ring A-A. In case of a dual-attachment node, the A-port should be connected to the B-port of its upstream neighbor and the B-port should be connected to the A-port of its downstream neighbor (unless dual-homing is used). Connecting the A-port of a dual-attachment node to the A-port of another dual-attachment node results in a topology that is referred to as a twisted ring. · Twisted ring B-B. This is similar to the twisted ring A-A topology explained above, except that it is caused by connecting the B-port of a dual-attachment node to a B-port of another dual-attachment node. · Wrap. FDDI defines a redundant topology network. If a fault occurs on the trunk ring, then the dual-attachment nodes on either side of the faulty link wrap around to bypass the faulty link These nodes are then said to be in a wrapped state. |
| The following information indicates how the node is connected to the FDDI ring:
· Rooted station/station not rooted. Displayed if the node is a station. A station is rooted if it does not have an active A, B, or S port in tree mode. This indicates whether the station is directly connected on the trunk ring (rooted), or if it is connected through a concentrator as part of a tree topology (unrooted). · Attached concentrator/unattached concentrator. Displayed if the node is a concentrator. · Unattached concentrator. Displayed if the node is a concentrator. A concentrator is unattached if it does not have an active A, B, or S port. In an FDDI dual-ring topology or a dual-ring-with-trees topology, all concentrators are normally attached. In an FDDI tree topology, any number of concentrators are arranged in a hierarchy, with a number of stations attached to each concentrator. In this topology, one concentrator is the root of the tree. This concentrator is unattached. All other concentrators are attached under normal conditions. | |
| Synchronous Service | FDDI allows for two different types of traffic, synchronous and asynchronous. Synchronous traffic consists of delay-sensitive traffic such as voice packets, which need to be transmitted within a certain time interval. Asynchronous traffic consists of data traffic produced by various computer communication applications, such as file transfer and mail, among others. These data packets can sustain some reasonable delay.
If the node supports synchronous traffic, the following is displayed: If it does not support synchronous traffic, the following is displayed: |
| Duplicate MAC Address Test
| On an operational FDDI ring, each node periodically checks to see if there exists any other node that has the same MAC address as its own. If a duplicate MAC address condition does not exist, then the following is displayed:
If not, then either of the following is displayed: |
You can view data on active stations. To do so, use the following procedure.
Step 1 Select the View menu.
Step 2 Click Active Stations Only.
You can change the way TrafficDirector sorts the information provided in the window's list by selecting Sort from the menu bar, then selecting one of the following:
| Ring Order | The position of the station in the ring. (The default.) |
| MAC Order | MAC addresses, sorted in descending order. |
| Enter Time | The last time the station has entered the ring, sorted in descending order. |
| Exit Time | The last time the station has exited the ring, sorted in descending order. |
To refresh the station list information to display the most recent data, click the Refresh button in the Ring Monitor window. TrafficDirector updates the list data.
You can launch the TrafficDirector Host List from the Ring Station List window to view a complete list of the hosts and host activity detected by the selected FDDI agent. You may use Host List to verify the number of hosts in a domain or that a host is included in a particular domain.
To launch Host List from the Ring Station List window, click the Host List button, or select Tools>Host List from the menu bar. When you do so, the RMON Host List main window is displayed (Figure 10-2).
You can now work with the Host List application as described in the "Monitoring and Troubleshooting Single Domains" chapter.
You may want to print the contents of the Ring Monitor list for future reference. To print the contents of the list, use the following procedure.
Step 1 Select File>Print from the menu bar. The Printing Options window is displayed (Figure 10-3).
Step 2 Do one of the following:
Step 3 Click OK.
To exit Ring Monitor, select File>Exit from the Ring Monitor main window menu bar.
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