Modify Network Sonar Discovery preferences
Some preferences can be changed to discover and scan your network.
- Click Discovery > Preferences.
- Click Discovery Performance, and then adjust the following:
Network Connection - This slider adjusts the speed of the network discovery. The discovery speed can be set from slow dial-up lines up to a high speed LAN. Network Sonar also automatically adjusts the speed of the discovery.
Network Congestion - This slider adjusts the default timeouts and retries for Network Sonar. Most of the time, set this to Normal. Network Sonar automatically adapts the network discovery if it starts to encounter problems or congestion in part of the network.
- Click Community Strings, and then add and adjust community strings.
The more community strings you add, the potentially increased time the network discovery takes. Arrange the most commonly used community strings at the top of the list.
- Click Automatic Subnet Selection, and then adjust the setting:
During a network discovery, Network Sonar may find subnets that it does not already have in the database. Network Sonar always adds the new subnet to the Discovery Database, and includes it in the active discovery based on these settings.
Exclude the new subnet from the network discovery - Select Exclude if you do not want any new subnets found during the discovery to be automatically scanned as part of the discovery. Network Sonar still adds the subnet to the database. You can always select the subnet later and resume the discovery to scan it.
Use this option if you are scanning part of the Internet (an ISP for example). You do not want Network Sonar to automatically include any new subnets in the active discovery. If it did, it would attempt to discover the entire Internet.
Include the new subnet in the network discovery - Select Include if you want new subnets found during the discovery to be automatically scanned as part of the discovery. This is useful when scanning a corporate Intranet to ensure Network Sonar scans every subnet.
Include the Subnet if it is smaller than - Set the size of the subnets that should be automatically included. Adjust the slider to change subnet mask size. All subnets smaller than this setting will be included in the active discovery.
- Click Ping Sweeps, and then adjust the settings:
- Delay between pings: the time in milliseconds to wait before sending PINGs to each node. This setting is used to arbitrarily slow down the network discovery. This is important on dial-up lines or to limit the amount of traffic generated by Network Sonar. Normally, you would not adjust this slider. Network Sonar makes any adjustments when needed.
PINGs transmitted per node: this setting is used to control how many PINGs should be sent to each IP address during scanning. Normally, this should be set to 2 or higher.
This is important when scanning networks using Cisco routers. If the target IP address is not in a Cisco router ARP cache, the router discards the ICMP query (PING) while it requests the MAC address of the target IP. The first PING never reaches the subnet of the target IP address. In this situation, the second PING is the one the target IP address responds to.
- Click ICMP, and then adjust the settings:
- PING Timeout: this setting is the number of milliseconds Network Sonar should wait for a reply before assuming that the target IP address is not responding.
- Packet Time-To-Live: the Packet Time-To-Live is the number of "hops" you will except in trip to the specified IP address. With a setting of 32, your PING test could pass through up to 32 different routers on the way to the remote IP address before being thrown away by the network. Normally you would set this to 32 hops.
- Click SNMP, and then adjust the settings:
- Packet Timeout: this setting is the number of milliseconds Network Sonar should wait for an SMNP reply before assuming the packet was lost and trying again. This setting should normally be set around 600 milliseconds.
- Query Attempts: this setting is the number of times Network Sonar should retry an SNMP query before giving up. This should normally be set to 2.