3.1 Setting Up a Network Inventory

Use the Set Up view to set the time when network discovery will begin and to select which network devices will be included in discovery scans. To access the Set Up view, expand the Network Inventory view tab and click the Set Up view tab.

Complete the fields in the Set Up view as described below:

Field

Description

Start discovery immediately upon activation

Tells the Vivinet Assessor Scheduler service to begin discovering devices on your network as soon as you click Activate Discovery in the Discover view

After activation, wait until [time of day] before starting discovery

Tells the Scheduler service to begin the process of discovering devices on your network at the specific time of day you entered. To notify the Scheduler, click Activate Discovery in the Discover view as soon as you complete the necessary setup tasks in the Set Up view.

SNMP Configuration

Simple Network Management Protocol (SNMP) permissions allow Vivinet Assessor to collect information from SNMP-enabled devices. Until you enter SNMP information into the database, Vivinet Assessor uses the default SNMP community string, public, which is probably not the correct one for your network.

The type of information you configure varies according to the version of SNMP that is implemented on the network device. Vivinet Assessor supports SNMP versions 1, 2, and 3.

The message "SNMP values are currently set to their defaults” indicates that you have not entered the SNMP information in use on your network. The Network Inventory probably cannot be performed if you do not enter at least one community string for versions 1 and 2, or security profiles for version 3.

Edit SNMP Configuration

Lets you enter your SNMP information to enable Network Inventory discovery scanning. For more information, see Section 3.1.1, Editing SNMP Configuration Information.

Use a default gateway

Enables Vivinet Assessor to query the gateway router whose address you specify to discover network devices and links from the gateway’s routing tables. This type of discovery is the default method for Vivinet Assessor. For more information, see Section 3.1.3, Using a Default Gateway.

Use specific addresses

Enables Vivinet Assessor to discover network devices and links by performing SNMP discovery scans within an IP network address range you specify. For more information, see Section 3.1.4, Using Specific Addresses for Discovery.

Discover Ethernet links

Tells Vivinet Assessor to include Ethernet LAN links (such as switches with Ethernet cables attached) on your network in discovery scanning. Discovered LAN links appear in the Network Inventory as Ethernet links and can be monitored for utilization and used for Bandwidth Modeling.

Some networks contain hundreds of Ethernet links that could potentially be discovered and included in the Network Inventory. If you enable this option, you could quickly exceed the maximum number of database objects your Vivinet Assessor license allows (1000 routers, switches, and links). This limit reflects the maximum number of objects that can be efficiently managed by the Vivinet Assessor database.

If you are using a default gateway for discovery, you should leave this option disabled to avoid discovering too many Ethernet links. However, if you want to discover Ethernet links, specify the address ranges you want to discover and then filter the network interface ports to which Ethernet links are connected for the devices in those ranges. For more information, see Section 3.1.4, Using Specific Addresses for Discovery.

3.1.1 Editing SNMP Configuration Information

Vivinet Assessor uses SNMP (Simple Network Management Protocol) to gather important information about VoIP data patterns and performance from your network hardware, including routers and VoIP gateways. You configure SNMP permissions to let Vivinet Assessor collect information from SNMP-enabled devices.

Enter SNMP information before running a discovery scan for the Network Inventory. Until you enter your information, Vivinet Assessor attempts to use only the SNMP default community string, “public,” to query your network devices. However, because the default string is not secure and therefore probably not in use on your network, or because you may have SNMP v3 in use in your environment, the discovery scan will fail unless you configure the proper SNMP information.

The information you configure varies according to the version of SNMP that is implemented on the network device. Vivinet Assessor supports SNMP versions 1, 2, and 3.

Uuse the Edit SNMP Configuration dialog box to add, edit, and delete SNMP information, and to set SNMP timeout and maximum retries.

Configuration for SNMP Versions 1 and 2

To add configuration information for SNMP v1 and v2:

  1. Click Edit SNMP Configuration in the Set Up view.

  2. On the SNMP v1/v2 tab, click Add.

  3. In the Add Community String dialog box, type the community string in use on your network and click OK. The SNMP community string acts as a password to yield access to the Management Information Base (MIB) of each VoIP device on your network. You should add each valid community string on your network to the list. Strings are limited to 63 characters. Read-only community strings are adequate; Vivinet Assessor does not need write access to SNMP devices. SNMP community strings are case-sensitive.

  4. Repeat step 3 for each community string in use on your network. Vivinet Assessor will try each one you enter in turn.

  5. To set timeout, click the Options tab.

    • In the SNMP timeout field, indicate the maximum amount of time (in milliseconds) the Vivinet Assessor Console will wait to receive a response to an SNMP query before sending a new query. Values must be from 500-5000 ms, inclusive. The default is 2000 ms.

    • In the SNMP maximum retries field, indicate the maximum number of times the Vivinet Assessor Console will try to reach a device that does not respond to an initial SNMP query. Values must be 0-5, inclusive. The default is 2 tries.

    NOTE:The values for timeout and maximum retries actually apply to the Utilization assessment, which uses the same SNMP information for utilization monitoring. Vivinet Assessor will not keep trying a community string again and again during Network Inventory discovery scans. Instead, it will assume that no devices are present.

  6. Click OK. The community string is displayed on the SNMP v1/v2 tab.

Configuration for SNMP Version 3

Vivinet Assessor supports the following security modes for SNMP v3:

  • No authentication; no privacy

  • Authentication; no privacy

  • Authentication and privacy

In addition, Vivinet Assessor supports two authentication protocols for SNMP v3:

  • MD5 (Message-Digest algorithm 5)

  • SHA (Secure Hash Algorithm)

and one privacy encryption protocol: DES (Data Encryption Standard).

Your SNMP v3 implementation may support one or more combinations of mode and protocol. That combination dictates the type of information you configure in Vivinet Assessor: user name (or entity), context name, protocol name, and protocol passwords.

Configure SNMP v3 information for each device that you want to include in the Network Inventory.

To add configuration information for SNMP v3:

  1. Click Edit SNMP Configuration in the Set Up view.

  2. On the SNMP v3 tab, click Add.

    • Select whether you will configure SNMP information for an IP Address or Range or a Hostname.

    • If you selected IP Address or Range: In the From field, type the first IP address in the range. In the To field, type the last IP address in the range. To configure one IP address, type the same IP address or hostname in both fields.

    • If you selected Hostname, type the hostname in the field to the right. Enter a fully qualified domain name (FQDN) rather than an IP address.

    • In the User name field, type the SNMP user name or entity configured for the device.

    • In the Context field, type the name of a context associated with the user name you entered in the User name field. A context is a collection of SNMP information that is accessible by an entity. If possible, enter a context that provides read access to all MIBs for a device. Leave the Context field blank if no context is associated with the user name.

    • For no authentication/no privacy mode, no further entries are required.

    • For authentication/no privacy mode, select Use Authentication, type md5 or sha in the Protocol field, and then type the associated password in the Password field.

    • For authentication/privacy mode, select Use Authentication, type md5 or sha in the Protocol field, and then type the associated password in the Password field. Finally, select Use Encryption and then type the DES password in the Password field.

    • Click OK. The SNMP configuration information is displayed on the SNMP v3 tab.

  3. Repeat step 2 for each set of SNMPv3 information you need to configure.

  4. To set timeout, click the Options tab.

    • In the SNMP timeout field, indicate the maximum amount of time (in milliseconds) the Vivinet Assessor Console will wait to receive a response to an SNMP query before sending a new query. Values must be from 500-5000 ms, inclusive. The default is 2000 ms.

    • In the SNMP maximum retries field, indicate the maximum number of times the Vivinet Assessor Console will try to reach a device that does not respond to an initial SNMP query. Values must be 0-5, inclusive. The default is 2 tries.

    NOTE:The values for timeout and maximum retries actually apply to the Utilization assessment, which uses the same SNMP information for utilization monitoring. Vivinet Assessor will not keep trying SNMP information again and again during Network Inventory discovery scans. Instead, it will assume that no devices are present.

  5. Click OK.

NOTE:You may notice a temporary spike in processor usage when discovering or monitoring network devices using SNMP v3. SNMP v3 requires additional overhead for authentication or encryption of query requests sent to the SNMP agent on the devices.

3.1.2 Setting Network Discovery Performance

You can complete the Network Inventory more quickly if you set a network discovery performance option before you activate discovery scanning. The Inventory Network task proceeds when Vivinet Assessor sends out a series of SNMP queries or performs a series of tasks, depending on whether you entered a range of IP network addresses or a default gateway router to be used in network discovery. The Vivinet Assessor Console can break subnets into separate sets of addresses and query them all simultaneously, or it can perform multiple discovery tasks at once. However, in each case, more bandwidth will be taken up with discovery traffic.

Therefore, you can request better performance from Vivinet Assessor network discovery, based on the bandwidth and other resources available on the network to be scanned. The performance option is also recommended in cases where discovery has failed to find any devices that are known to be on the network. In such a case, a slower link may be dropping the SNMP packets used to find devices, and slowing the rate of discovery will solve the problem.

As a rule, the faster discovery is completed, the more bandwidth it requires. However, performance also depends on the available resources on the Console computer (including NIC, memory, and CPU), as well as the speeds, current utilization levels, and maximum allowable utilization levels of all the links and devices in the paths to discovered devices.

To set discovery performance:

  1. On the Options menu, click Performance.

  2. To increase the speed of discovery, move the slider to the right.

  3. To decrease the speed of discovery, move the slider to the left.

  4. Click OK.

HINT:As discovery proceeds, check the Error Log. You will know that you set the speed too high if you see any SNMP timeout errors. Similarly, you should lower the speed if any device known to be active on the network is not discovered.

3.1.3 Using a Default Gateway

If you are not certain of all relevant subnets that should be scanned during Network Inventory discovery scanning, you can instruct Vivinet Assessor to perform device and link discovery based on a “seed” or default gateway (a router) whose IP network address is known. Vivinet Assessor will query the gateway for its routing tables and then attempt to discover every device from the addresses in the tables.

By default, Vivinet Assessor uses the “Use a default gateway” method of discovery. Because using a default gateway requires Vivinet Assessor to learn about the network from scratch and scan many subnets, Network Inventory discovery scanning goes much more quickly if you instead enter specific ranges of IP network addresses in the Set Up view. For more information, see Section 3.1.4, Using Specific Addresses for Discovery.

To identify a default gateway:

  1. Select Use a default gateway.

  2. In the Default gateway field, type the IP network address of the gateway (router) to query during discovery.

  3. Use the Max hops field to limit the scope of discovery to a certain number of router hops. Values must be 1-20, inclusive.

    NOTE:Discovery considers the gateway router itself to be the first hop. Therefore, a Max hops setting of 1 means you will discover only the networks directly connected to the gateway router, and no other routers.

  4. Click Verify to run a quick query on the default gateway to ensure that Vivinet Assessor can communicate with the gateway.

If you selected Use a default gateway, you can exclude certain IP network address ranges from discovery scanning.

To exclude IP address ranges from network discovery:

  1. Click Add.

  2. In the From field, type the first IP address in the range that you want to exclude from discovery.

  3. In the To field, type the last IP address in the range that you want to exclude from discovery.

    • Enter IP addresses in dotted notation, such as 123.45.67.89. Valid address ranges span from 1.0.0.0 to 223.255.255.255. Values higher than 223 in the first octet are reserved for IP Multicast.

    • The value you enter in the To field must be greater than the value you enter in the From field.

  4. To exclude a single address, leave the From field blank and enter the single address in the To field.

  5. Select Exclude this range from network discovery. If you perform a subsequent discovery scan, you can include this range by clearing this box.

  6. Click OK. The range is displayed in the Excluded Range list.

3.1.4 Using Specific Addresses for Discovery

If you know the range of IP network addresses or Ethernet network interface ports where device and link discovery should take place, you can specify the ranges in the Add to List of Discovery Ranges dialog box. Vivinet Assessor discovers network devices and links within the ranges you specify.

The IP address range you enter here may also be used later for endpoint discovery as part of the VoIP Quality assessment. For more information, see Section 7.3, Discovering.

To use specific addresses for discovery:

  1. Expand the Network Inventory view tab and click the Set Up tab.

  2. In the Discovery Type section, click Use specific addresses.

  3. Click Add.

  4. In the From field, type the first IP address in the range that you want to include in discovery.

  5. In the To field, type the last IP address in the range that you want to include in discovery.

    • Enter IP addresses in dotted notation, such as 123.45.67.89. Valid address ranges span from 1.0.0.0 to 223.255.255.255. Values higher than 223 in the first octet are reserved for IP Multicast.

    • The value you enter in the To field must be greater than the value you enter in the From field.

  6. To include a single address, leave the From field blank and enter the single address in the To field.

  7. Select Use this range in discovery if you want discovery scans to look for switches, routers, and links in this range of addresses. If you perform a subsequent discovery scan, you can exclude this range by clearing this box.

  8. Use the fields in the Ethernet Links panel to limit the number of Ethernet links that are discovered. Type a range of Ethernet network interface port numbers that you want to discover within the IP address range you specified in the Address Range panel. In the first field, type the first port number in the range. In the second field, type the last port number in the range. These fields are available only if you checked Discover Ethernet links on the Set Up tab. For more information, see Section 3.1, Setting Up a Network Inventory.

  9. Click OK. The IP address range is displayed in the Range column and the port range is displayed in the Port Range for Ethernet Links column.