The Switch Port Management (SPM) features in NetMRI allow at-a-glance management of all switched access interfaces in the network. IT departments routinely under-estimate (and over-estimate) port utilization and capacity requirements. In a large, switched spanning-tree network, some switches can go under-utilized while other switches in the network absorb unacceptably high loads. Switch port utilization trends are difficult to identify–is switch port utilization static, increasing or decreasing? Where are usage trends increasing? Decreasing? If certain switches support hosts that frequently leave their network segment (on business trips, for example) only to return within a week or two, how does the network manager control those temporarily vacated ports so that they remain available for their returning hosts?
Users often confront issues such as rogue/unknown devices on their switched networks, devices that frequently shift between switch segments, and a general lack of ability to track who connects when and where. Lacking adequate capacity planning, users sometimes resort to investing in expensive switch capacity "just to be safe."
NetMRI's Switch Port Management (SPM) page (Network Explorer –> Switch Port Management) solves all of these issues. SPM enables both big-picture and highly focused views of an entire switched Ethernet network, from the overall network layer to individual devices and interfaces. Extending throughout the entire switched network, all endpoints are detected, tabulated and monitored by NetMRI.
NetMRI can perform near-real-time polling of any part of the switched Ethernet network from the distribution level to any LAN switch. Network polling settings can be customized for any device group and administrators can execute a poll of a device group or the entire switched network at any time.
In a large-scale switched network, it can also be difficult to perform basic troubleshooting–locating the affected devices and analyzing their switch-port configuration. Through specialized reports, Switch Port Management gives administrators an integrated tool by which they can quickly learn the switch port settings of the interface to which any given device connects, including line speed, duplex, link status, VLAN ID and other information.
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Note: The switches and switch-routers have already been discovered by NetMRI. Switch Port Management polls switches for a detailed collection of information on switch port connectivity, status of ports and end devices. For information, see Running the Setup Wizard, Configuring Network Discovery Settings and Running Network Discovery on Routed and Switched Networks.
NetMRI gives explicitly licensed devices priority in determining which devices to manage. Unlicensed devices continue to be managed by the appliance, but the appliance periodically collects only basic discovery data. See Other Network View Operations for more information.
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- Available Ports %: The percentage of all managed switch ports appearing as Available.
- PoE Ports: The count of Cisco switched Ethernet ports running the Power over Ethernet switching protocol for IP telephony applications.
Choosing Devices Present shows the total of all switches' contributions to each of the six capacity categories. Choosing any other device group rewrites the Capacity Summary – Ports pane to reflect the subset of values for the selected device group
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Beneath the Capacity Summary – Ports pane, the Devices Present table appears displaying the data sets for all devices in the chosen data group. Each table row reflects a data set record obtained from LAN switching devices from a process called polling. The Devices Present table designation is for all devices in the chosen data set–not for all devices in the network.
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All tables in the Switch Port Management console provide an
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Clicking the Action icon for any table record in SPM displays a dropdown menu with differing options based upon the network entity type listed in the respective tables.
The Devices, Interfaces and End Hosts data categories provide different Action menus based on the table selection. The following sections describe switch port Actions menu options for each category.
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Switch Port Management (SPM) Date/Period menus enable flexible measurement and reporting for any device, interface or end host. You can effectively go bacbackwards
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For any page in SPM, clicking the icon on the top left of the table displays the Select Date/Period menu. The Select Date/Period menu fixes the current SPM page to a specific date or range of dates, going backwards from the current date, using a drop-down calendar.
Calendar dates shown in Green represent an immediately available data set to display in a Switch Port Management table. The most current data in any SPM table (such as the most recent 7 days for the Daily selection) is always available by default and appears highlighted in green. Older data requires the user to wait while NetMRI generates the requested data as a background task. After generation, the requested date appears in green, indicating the data is instantly available by reloading the page. Any date in the past or in the future appearing in grey that cannot be selected, represents information that is unavailable to the current NetMRI system.
Consider the Device category, with the default time measurement set to Daily.
As an example, you decide to look at the list of network switches that have changed in their status or their configuration over the previous 30 days from the current date. Choose Devices –> Changed Devices, click the Select Date/Period icon, and choose the time period (Daily, Weekly, Monthly, 7-Day or 30-Day). The time window shown in the currently selected page changes to the new value, and the current page changes in a number of ways:
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Network device polling is the key mechanism for building Switch Port Management (SPM)'s switching information, and the polling features provide considerable flexibility. You use polling at the Device Group level to check for changes to any active device in that group. You can define polling time periods for individual device groups so that administrators have near-real-time capabilities for
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In all cases, a polling schedule indicates the start of a polling cycle. Any given network device may not be polled at the specific time when the scheduled polling cycle begins; this is particularly likely when many devices are being polled during the cycle. The duration of a polling cycle may take some time.
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Periodic polling settings can be adjusted globally and within each device group. Periodic polling provides for the following rates: 30/45/60/90 minutes, then every hour up to and including 24 hours.
NetMRI always logs the elapsed polling time period for any network device regardless of the installed license for the current instance.
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You may exclude device groups from Switch Port Management; the switches within the chosen group will not appear in the Devices page and their switch ports will not count against the SPM interface license count, or in the Capacity Summary – Ports pane. Switch Port Management will not poll excluded device groups.
Device polling combines with NetMRI's configuration management features (the ability, for example, to quickly pull up and edit a given LAN or distribution switch's configuration files) to provide a workflow to quickly respond to issues in the switched network.
Multiple polling schedules can be applied per device group. For example, a user can schedule polling to run every Sunday at 3AM and 6PM.
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Infoblox recommends regular collection of interface performance statistics for Switch Port Management-managed systems, differing from the irregular or lengthy time periods used by the automatic collection of switch-forwarding data in the full NetMRI configuration. For information on switched interface management, see Managing Interfaces Through Switch Port Management.
Performance polling can be executed immediately, on demand, with limitations. If someone manually attempts to poll a device group when another poll of the entire network is already running, NetMRI notifies the user that another polling session is already in progress and will not execute the manual request until the current session completes.
Infoblox advises regular performance polling because interface-level performance statistics are provided to the appliance as counter values. NetMRI tracks differences in performance counter values from poll to poll and uses the deltas to calculate the true interface performance statistics over that time period. A regular time period provides greater granularity to the performance data and minimizes the changes of counter roll-overs.
For switch port management, interface performance statistics collection applies only to ports in Switch and Switch-Router devices.
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Switch Port Management (SPM) allows on-demand polling for device groups and for the entire managed network. A key use case is to check for changes to switches or switch ports in the network. In most cases, polling globally across the entire network should be discouraged in favor of polling across a single device group. When a polling session takes place, NetMRI commits a record of each polled network entity to the Device History, to the Interface History in the Interface Viewer; and to the Device History of any end devices involved in the group poll.
On-demand polling of switching devices can be executed for the entire switched network or by smaller Device Groups:
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The Device History and Interface History record all polling events for the chosen entities.
NetMRI users can view interface performance statistics In the Switch Port Management page view after the appliance collects all switch forwarding data.
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In Switch Port Management (SPM), devices denote network switches and switch-routers only. End hosts are counted as a separate category. The Devices pages provide the views of all the distribution and LAN switches and
switchand switch-routers in the managed network.
The Action column on the far left of any Device-related table (such as DevicesPresent), provides the following functions for switching device management from the NetMRI console:
- View Device History: Choosing this option displays the Device Viewer in a separate browser window. The device window automatically displays the Device History, with the most recent History record at the top. In the Device History view, the First Seen time stamp is the first time the device's MAC address was discovered.
- The
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- Last Seen timestamp represents the most recent time that NetMRI communicated with the device (often the most recent polling event). The device Name is the configured name of the switching device. The device's IP address is also shown, along with the DNSName if any. A standard Description (taken directly from the device) is given along with the PollDuration. If the PollDuration shows a value of "1" the polling process completed in the normal time period.
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Note: SPM tracks MAC addresses and their associated IP and switch port history. SPM separately maintains an active record of all MACs ever seen by the NetMRI system, along with their associated connectivity information.
Unique identities for all detected End Hosts are established by their respective MAC addresses.
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- OpenTelnetSession: Uses the Telnet/SSH proxy built-in to NetMRI to start a Telnet session with the selected device. OpenSSHSession: Uses the Telnet/SSH proxy built-in to NetMRI to start an SSH session with the selected device.
- TopologyViewer: Through a second-level dropdown menu, gives quick access to Layer 2 and Layer 3 views of the network topology surrounding the chosen device. If the selected device is classified as a Switch, only the L2nHop and L2/L3PathViewer topology views are available.
- L2 nHop: Shows the devices that can be reached from a starting device through a given number of Level 2 (actually a hybrid of L1 and L2) connections.
- L3nHop: Shows devices that can be reached from a starting device through a given number of routed Level 3 connections.
- L3PathViewer: Shows the most likely path traffic would take, ignoring Layer 2 connectivity and concentrating on L3 reachability and the "best" path for communication between Layer 3 devices.
- L2/L3PathViewer: Shows the most likely path traffic would take between two devices, including both Layer 2 and Layer 3 connectivity.
Also see Using the Topology Viewer for more information on how to use this NetMRI feature.
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The Devices Present link (Network Explorer–> Switch Port Management–> Devices –> Devices Present) is the top-level view in Switch Port Management. It provides the complete list of switches and switch routers that are being managed by NetMRI. The Capacity Summary– Ports pane appears at the top of the table, showing the network totals for Free Ports and Available Ports.
The Devices Present table breaks down this information into each switch's share of network capacity:
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The New Devices table lists the subset of switching network devices that have been discovered by NetMRI during the displayed measurement period. By default, the table is sorted in ascending order by the Device Name. These devices are not yet considered to be actively managed by NetMRI.
The default data set includes the following:
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The Changed Devices page lists any network devices that have changed in some fashion within the most recent polling time period. All newly discovered devices appear in this table; devices may move from one VLAN to another VLAN and also appear here. If a device is previously administratively Up but is taken down for any reason, it also appears here. The devices listed here represent a smaller subset of the total of network devices, and the Capacity Summary– Ports pane changes values to match.
Default data sets shown in the table include the following:
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The Devices Not Present page lists the subset of active switch and switch-router devices, excluding end hosts, with which Switch Port Management has lost communication over the last measurement time period. The device is off the network for some reason, such as having been turned off or rebooted or having settings changed so that it is out of Discovery range.
The default Devices Not Present page consists of the following data set:
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The Actions column of any Interface-related table (Ports Present, Link Changes and Hub Locator) provides a View Interface History function for LAN interface management from the Interface Viewer.
All ports that appear in tables described in this section are a subset of all ports discovered and managed by NetMRI. Interface tables outside of the Switch Port Management feature set will include such items as trunk ports and routed ports from routers and switch routers as catalogued and described by NetMRI.
View Interface History displays the Interface Viewer in
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Note: If the operating status of an interface is shown as “down” in the If Oper Status column, the VLAN information for this interface may be incomplete.
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You can trace the path of an L3 switched VLAN using the Topology Viewer. For information, see VLAN Tracing.
Also see Using the Interface Viewer for more information on how to use this NetMRI feature set.
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- Action icon: provides the Action menu with View Device History, Set Admin Status, Edit Description and Topology Viewer options.
- Device Name: The Ethernet switching device to which the interface is associated (live link to the Device Viewer, displaying the Issues page).
- Interface: The switched port identifier (live link to the Interface Viewer, displays the History of the port).
- Interface Type: The standard interface type supported by the port. For switched Ethernet, this value will typically be ethernet-csmacd.
- Interface MAC: The 48-bit hardware address for each port in the Link Changes list (live link to the Interface Viewer, displays the History of the port).
- If Oper Status: the switched interface's operating status.
- If Admin Status: the switch port's Admin status (if the port is administratively enabled by the operator).
- # End Hosts: The number of detected End Hosts bound to the hub interface (live link to the End Hosts Present page). The Hub Locator table is sorted in descending order by this column.
- First Seen: The timestamp indicating when Switch Port Management first polled the device.
- Last Seen: The timestamp indicating the last occasion when Switch Port Management detected the device on the network.
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The Refine View tool is helpful for tracing the path of a L3 switched VLAN.
Every device in a Device Group that participates in the same switched VLAN can be marked using this feature. To perform any VLAN path trace, click on Network Explorer –> Topology –> Network accordion menu –> Aggregate and click the Refine View button.
The Edit View dialog appears, displaying the Device Group tab.
Hover the mouse over the Action icon for the VLAN ID that you want to use as the basis for your VLAN path trace. Choose Select Blue or Select Yellow from the Actions pop-up menu. The color for the VLAN ID appears under the Selections column. Click OK, and the Topology map redraws to add color markers to all devices in the map corresponding to the chosen VLAN ID.
You can hover the mouse over the devices carrying the VLAN, and over the links between devices to get more information about each link.
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In the Switch Port Management page, the End Devices category displays all end host devices associated with LAN switches in the selected device group, and filters them into several functional categories.
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- Action icon: provides the Action menu with End Host History, Interface History and Device History options, changing the Admin Status for an end host interface, and editing the description and VLAN assignment.
- Host IP address: The IP address of the end host, provides live link to the Device Viewer.
- Host Name: The DNS host name (if any), provides live link to the Device Viewer.
- Host MAC: 48-bit hardware address of the end host's Ethernet port.
- Last Seen: The timestamp of the most recent detection of the end host connected to the given VLAN. (You can also choose to display the First Seen data column, which is the timestamp of the moment when the end host was first detected by NetMRI as a host connected to its current LAN switch interface.
- Device Name: The LAN switching device to which the host is currently associated (live link to the Device Viewer).
- Interface: The LAN switched interface to which the end host connects (live link to the Interface Viewer).
- If Oper Status: The LAN switched interface's operating status (live link to the Interface Viewer).
- VLAN Name: The active VLAN to which the end host is currently bound (live link to the VLAN Viewer).
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The VLAN Viewer is a pop-up browser window that provides table rows listing several basic characteristics of a selected virtual LAN interface, including all switches that terminate the VLAN.
Most of the key information about a VLAN appears in the top section of the Viewer, including the Root Bridge, the root bridge priority and ID, and its configured Max Age, Hello Time and Bridge FWD Delay values.
Important table data columns include the Priority field, the Bridge Address, and a Timers field showing the status of spanning tree timers for VLAN switching.
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Note: See Viewing Active VLANs and VLAN Configuration for more details about VLAN settings displayed in the Device Viewer and the VLAN Viewer.
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Settings
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Switch Port Management provides for a set period of days after an SPM port is free and unused before it is specifically defined as Available. When a port is first disconnected from all other devices, it is in a Down link state, and appears in the Free category. After a certain time period elapses (the duration of which is based on the business policies of the IT department), the port is counted against the Available category and removed from the Free category, because its link state has been down for longer than the specified time period.
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NetMRI uses ARP cache refresh to control LAN switches from which switch-forwarding data is collected.
When ARP cache refresh is enabled for a LAN switch, before further collection of switch-forwarding data, NetMRI pings all known IP addresses known to exist as members of the device's switch-forwarding table, by relating previously gathered switch-forwarding data MAC addresses to determine their IP addresses. Because this requires a prior SPM poll, the first poll of any switch by SPM after the device is added to the license will not perform an ARP cache refresh.
For subsequent polling events, NetMRI performs ARP cache refresh by sending a UDP packet on Port 80 to each IP address in the switch's forwarding table, without waiting for return messages. This has the effect of re-populating the switches' forwarding table. NetMRI sends nothing to the switches themselves, the refresh is performed against all the end hosts and other devices connected to each LAN or distribution switch.
The appliance also tracks the time period required to collect switch-forwarding data and compare the result to the last ARP refresh. Once a timeout period is exceeded, NetMRI will re-perform the refresh on the switch, and repeat as necessary as data is collected from the device.
The appliance automatically performs an ARP cache refresh immediately before a new switch port polling session.