Censusby Steward IT

Documentation › Using Steward IT Census

Network map

Assets › Network map draws your switches, routers, firewalls and access points and how they are connected, and every computer's asset page shows which switch port it is plugged into. The data comes from the network devices themselves, read by SNMP during network scans:

From the device Shows
LLDP neighbors (LLDP-MIB), CDP on Cisco which device is on the other end of each port, and its port name; the links on the map
MAC address table (BRIDGE-MIB / Q-BRIDGE-MIB) which computers, printers and phones are plugged into each port, with their VLAN
Interfaces (IF-MIB) port names, descriptions, up/down status and speed

Setting it up#

  1. Add an SNMP credential (Scanning › Credentials) that your switches and routers accept. SNMP v2c (community) and v3 are supported; read-only access is enough.
  2. Make sure the devices' management addresses are inside a scan target, then run the scan.
  3. Turn on LLDP on the switches if it's off (most managed switches have it on by default; on Cisco, CDP works too).

The map fills in as switches are scanned; the switch-port information on computers appears once the switches' MAC tables have been read.

Reading the map#

  • Each box is a device that reports network data, or a neighbor it reported. Gray boxes are neighbors that aren't assets yet (for example access points or phones the scan didn't inventory); scanning their addresses turns them into assets.
  • The device with the most connections is at the top, its neighbors below it. Thick lines connect two switching or routing devices (uplinks); hover a line to see the port on each end.
  • The number on a switch is how many devices are plugged into its ports. Click the number to show that switch's ports that have devices plugged in (with how many on each), and click a port to show its devices; click again to hide them, or Hide the ports. One switch's ports are shown at a time: opening another switch closes the first. Click a device to zoom onto it and open its Ports tab.
  • The faint pulses running along the lines move toward the uplinks.
  • IP phones and computers that announce themselves over LLDP are hidden to keep the map readable; Show end devices adds them.
  • Drag to move the map, scroll to zoom, Fit to see everything again.

Is everything answering?#

When the map opens, Census checks whether each device on it answers, the same way as the live status on an asset's page: a connected Census agent, else ping and the usual ports (plus your custom ports); devices at a remote site are checked by that site's scanner. A small dot on each device shows the result:

  • Green: answering.
  • Amber: no answer to the last check; Census checks again before calling it down, so one lost ping doesn't raise the alarm.
  • Red, with a red outline and its links dashed red: no answer to two checks in a row. The line above the map names every device that isn't answering and since when.
  • Gray: can't be checked (for example a remote site whose scanner is offline). Hover the device for the reason.

Tick Watch live to keep checking every 30 seconds (or every minute) while you look at the map, for example during an outage. Only the first check of a device tries the usual ports; while it keeps answering, later checks touch just the port (or ping) that answered, so watching the map doesn't look like a port scan to an intrusion prevention system. When that one stops answering, the full check runs at once before the device turns amber. Each device that stops answering, or answers again, pops up a notice and is added to a list under the status line. Watch live turns off when you go to another page.

The map only checks while someone has it open. To be told about an outage at any time, use the Asset not answering alert for a group with your switches and routers.

Ports tab#

A switch's Ports tab lists every port with its status, speed and description, the LLDP/CDP neighbor on it, and the devices plugged into it (linked to their assets, or shown with MAC address and manufacturer when they aren't inventoried).

A device appears on the port where the fewest other devices are seen, and ports with a switch or router on the other end are ignored, so a computer is listed on its access port, not on every uplink between it and the core.

Switch port on computers#

A computer's Network tab shows the switch and port each of its network adapters is plugged into, with the VLAN, and which switches see it over LLDP/CDP (servers running an LLDP agent).

Limits#

  • Cisco IOS keeps a separate MAC table per VLAN. Census reads the VLAN list (VTP MIB) and then each VLAN's table with community string indexing (community@10 for SNMP v1/v2c) or the SNMPv3 context vlan-10, so Cisco ports list their devices with the VLAN. Your SNMP view must allow it: for v3, give the group access to the vlan- contexts (snmp-server group NAME v3 priv context vlan- match prefix). If a switch doesn't answer for five VLANs in a row, Census stops asking it for per-VLAN tables. Most other managed switches publish all VLANs in the standard Q-BRIDGE-MIB.
  • Unmanaged switches don't answer SNMP: devices behind one show up on the managed switch port the unmanaged switch is connected to.
  • The map's devices, links and ports are as fresh as the last scan of each switch; only the answering check is live.