Using Topology Manager

Introduction

Topology Manager (TM) allows you to discover your Bay Networks devices and their physical (layer 2) links and view them in a topology map.  TM is designed for small to medium networks of Accelar routing-switches.  Even so, it will discover all devices that implement the Bay Topology Protocol (BTP), using the Bay Topology MIB, however certain features are only available for the Accelar family.

TM is designed to work with other network management applications; notably Device Manager (DM), VLAN Manager (VM), and Route Manager (RM).

Discovering Your Network

Discovery begins by querying a device's Topology Table via SNMP.  (This device is called the seed device.)  The BTP table reports the device's immediate neighbors which respond using BTP.  We know the neighbor's IP Address, port interface, and device type.  We then query all the neighbors in a similar manner to the seed device, but in parallel.  This continues until there are no more responses to process.  By default, TM won't query neighbors more than 5 hops away from the seed device.  In addition, the discovery process can be stopped by the user at any time.

After all the devices have been discovered, the TM will reduce the discovered IP addresses down into a single set of devices (routers usually have multiple IP addresses per interface).  Then the links between the devices are computed.

Sometimes a network is not completely connected with BTP, but you may still wish to view these BTP islands in your map. To do this, you must specify multiple, colon separated, seed addresses. Each seed must be within a BTP island.Of course, the islands are not connected together.

Map Layout

As devices are discovered, they are displayed by column (top down, left to right)  in the map. In order to view the network coherently you must ask TM to layout the map (Actions->Layout). TM uses the (somewhat unsophisticated) Spring algorithm to balance distances between devices and minimize crossing lines. You can improve the layout by adjusting the Layout slider  in Edit->Preferences. However, you may have to manually layout some devices in order to get a more readable map. TM remembers this layout until you rediscover your network again.

If you rediscover the same network, any new device will be placed by column in the map.  Existing devices will not be moved.  Devices which are no longer reachable will be grayed out.  You can relayout the entire map or drag the newly discovered devices to the desired location.  If you wish to discover the network afresh, you must delete the existing network prior to discovery.

TM provides 4 zoom levels to magnify your map. The first (x1) is the default view. TM will attempt to place all discovered devices on screen. Depending on the number of discovered devices, TM will not display link labels or even device labels. As you increase the scale, TM will add link and device labels as necessary.  If device labels are not displayed at the current zoom level, you will see tool tips describe the node icons if your pointer rests over them.

TM uses icons to classify network devices into four broad categories:

  1. Hubs or Buses.  These appear whenever a single port sees multiple ports as destinations.  Hubs are not manageable.  Grayed out numbers appear just for identification; they have no network meaning.
  2. Layer-2 (Bridging) Switches.  Examples are the 303, 410, and the 450.
  3. Layer-3 (Bridging/Routing) Switches.  Examples are the Accelars.
  4. Routers.
If a device is unreachable, the color will change from black to gray.  Devices are unreachable for two reasons:
  • no route exists to the device, you can confirm this by Pinging the device.
  • the SNMP community string is invalid.

    • Map Operations

    All devices have a popup menu containing Telnet, DM, Properties, and Ping.

    When requested, links are displayed in three different thickness and colors according to link speed: 10Mbps (magenta), 100Mbps (blue), or 1Gbps (red).

    Each link has two labels - one per port. Port names are shown as card/port. If the port's IP Address is different than it's device, the address is appended to the port name.

    The icons are illustrated in Help->Legend.

    Topology Manager Window

    The TM window contains three elements: a menu bar, toolbar and map window. The menu bar and toolbar are standard GUI components. The Map window contains the (scrollable) view of the network topology map.

    The Log window displays status and error messages. You can view the contents of this window using View->Error Log.

    Commands

    File->Open, Save.
    These standard commands apply to the map window. When TM starts, it will try to open the file default.topo in order to display the current map. When TM quits, it will attempt to save the current map to the same file. You can manipulate map files with the open or save commands.
    File->Print.
    Print will display a standard dialog to print the map window.  TM doesn't paginate the map; i.e. it doesn't break the map printing into several pages.  If you want to print a portion of the map, you must ensure that that portion is visible in the window at the desired zoom level.
    Edit->Communities.
    SNMP devices typically have two passwords (called communities) for read and write operations. By default, TM assumes that all devices have public/private as their communities. However, network administrators often assign different communities to devices under their control. TM uses a wildcarding scheme to associate communities with groups of devices. For example, 134.160.170.0 refers to all addresses in that subnet. Similarly, 134.0.0.0 refers to all addresses beginning with 134. A specific address, e.g. 134.160.170.2, will override the communities specified by the wild card 134.160.170.0. The 0 wild card can be places anywhere, e.g. 134.160.0.1 will associate communities with all addresses in the 134.160 subnet that end in 1.

    TM reads and writes the communities database to the ASCII file snmpcomm.properties. The Save button will write any changes to this file. If all entries are deleted, TM will default to the standard communities public/private.

    Edit->Preferences.
    Discovery describes the network discovery attributes.  The Seed Address(es) and MaxHops have been discussed above.  You can restrict what devices are discovered in the Restrict Discovery window.

    Map describes how map window attributes:

  • Layout adjusts the Spring Algorithm iterations.  Fewer iterations complete faster but result in a poorer quality map.
  • Show Node defaults to IP Address, but you can show by DNS Host name or MIB 2 sysName.
  • Trim Hostname would trim foo.bar.com to foo.
  • Non-highlighted items are dimmed by default.  This allows you to concentrate on the highlighted nodes but be aware of the context.  If you wish, you can remove the non-highlighted items from the map.
  • Device Manager defaults to the Tcl/Tk DM, you can request the Java DM to be used instead.  (This option will eventually default to the Java DM.)
  • Automatically Save will be default save the current map to default.topo.


    • SNMP controls the discovery packets to the device.

    Edit->Clear Map.
    This command deletes the current in-memory map.  It will not affect default.topo unless Automatically Save is enabled and you close TM.
    View->Link Speeds, Duplex, Multi-link Trunks.
    To avoid clutter, link speed, duplex and MLT (Multi-Link Trunking) are not shown by default.

    Link speed is shown by a line thickness (and colors) of 1, 2, or 3 according to 10Mbps, 100Mbps, or 1Gbps.  The legend will appear at the bottom right-hand side.

    Link duplex is shown by color.  The legend will appear at the bottom right-hand side.

    MLT is shown by a bundle icon across the center of the links.

    Actions->Tool Launching.
    The actions menu allows you to launch the VLAN Manager (VM) and Route Manager (RM).

    Troubleshooting.

    1. Why doesn't TM doesn't show me all my network devices?
    1. Some devices are not reachable from the NMS.  Use the Ping window to confirm.
    2. Some devices have disabled topology.
    3. Some devices don't support the topology MIB.
    4. Some devices are more than 5 hops away from the seed device.  (Increase the maximum hopcount in the Edit->Preferences dialog.)
    5. Some devices have timed out.  Look at the log panel.  This can be due to two reasons:


      6. 1. Invalid read-community string: add correct community in the Edit->Communities dialog.
      2. Slow network: increase the retries in the Edit->Preferences dialog.
      3. NMS socket overflow.  Occasionally, when discovering large networks, some packets are dropped at the NMS.  You can control this by reducing the maximum outstanding PDU queue size to throttle back traffic.  Set the Max Outstanding Requests in the SNMP Preferences.