IED Network Quick Reference

12 Feb 2018 - This article has been superceded by the Network Design Considerations document referenced in this Zendesk Article.


Network Requirements Summary


Ethernet Switches

High quality Ethernet switches are necessary for reliable performance. Consumer and value-priced commercial switches are practical only when longer latency, dropped frames, or full buffers are not noticeable. Regular business applications, internet browsing, files transfers, etc. can tolerate limited performance from the switches and network; audio networks cannot.

These switch types have been successfully deployed in facilities that utilize IED products:  Cisco 2960 series, HP Procurve series 2600,J8762A (2600-8-PWR)

Required Switch Features

With a Networked IED PA system, Network switch quality is critical for reliable performance. The switches must support the following features:

  • Non-Blocking Switch Fabric Speed (Backplane speed)
  • Allows assignment of switch IP addresses for remote monitoring and configuration via GUI interface
  • Allows assignment of Manual Port Speed and Negotiation
  • Supports VLAN’s and Tagging
  • Supports Port Monitoring Capability
  • Supports Quality of Service (QoS)
  • Supports Spanning Tree Protocol
  • Allows manual configuration of the MAC Aging Timeout (IED recommends setting the limits to the maximum amount of available, preferably unlimited)
  • Allows deactivation of the Link Aggregation Control Protocol (LACP) which is known to cause interference in networks environments that rely on multicast traffic for system communication.
  • Support multicast and unicast filtering of ports.

Note: This is a port-based filter and will only be required on devices which are not utilizing the CobraNet® audio or control.

  • Includes a minimum of 32Mb of Ram for data buffering
  • Supports IGMPv3
  • Must turn off Energy Efficient Ethernet

Feature Descriptions

  1. Managed Switch – A managed switch can be assigned an IP address to make monitoring and configuration easier.
  2. Port Configuration – Manual port speed and negotiation settings. It is often necessary to manually set the port speed on certain devices to ensure proper communication.
  3. VLANs – VLAN creation and assignment for segregating traffic to its own “network” inside the switch. If a dedicated network is not available or feasible, then a VLAN becomes a requirement. In a shared network environment the IED system must be on it’s own VLAN(s).
  4. Port Monitoring – Port monitoring or “mirroring” gives an administrator the capability to watch traffic on a specific port. This is helpful when trying to troubleshoot network communication issues.
  5. QoS – Quality of Service (QoS) allows specific protocols or switch ports a higher priority on the network. This ensures that crucial traffic, such as voice data and/or CobraNet, is delivered without any transmission retries or packet loss. IED must have QoS Guaranteed service (also called hard QoS).
  6. Spanning Tree Protocol – Spanning Tree Protocol (STP), also known as meshing, provides redundant paths for fault tolerance. One path has a higher priority than the other. This priority makes sure that only one path is open for data travel at a time to avoid network loops, also known as broadcast storms. This allows for a more simplified configuration deployment.
  7. Switch Memory – A minimum of 32Mb RAM allows for data buffering and contributes to the overall efficiency of the switching fabric.
  8. Layer 2 – Switches by nature are layer 2 however it must be noted that the technology IED uses from Cirrus Logic®, known as CobraNet®, operates only on Layer 2.

Virtually any Layer 3 switch can meet the requirements listed above. IED recommends the use of Cisco 29xx (or higher) series of switches.   Cisco Catalyst 2960 and Catalyst 3750, and HP J8762A ProCurve 2600 are known to be deployed successfully in the field.


Protocols and Ports


The following table illustrates network protocols necessary for an IED vACS installation to properly function:





Port Number


Standard web protocol for communicating between vACS Server and client PCs. Used with T-CAS product.




Proprietary protocol for data communication between endpoints and their associated vACS.




Simple Network Management Protocol. Used for network device discovery.




Allows network “ping” to other devices.





Forwarding Delay


It is imperative that the aggregate delay from any two points located at the extreme edges of the network diameter not exceed the maximum allowed delay of 3.4ms. Operating beyond the recommended six (6) switch hops introduces the potential to exceed the maximum allowable delay of 3.4 ms.






There are some network commonalities that have been identified in facilities that have stable network communications while using IED CobraNet® based equipment.  Most of these are common across the recommended brands of network switches and if not will be otherwise noted.


Settings of note

  • No aaa new-model
  • System mtu routing 1500
  • Spanning-tree mode pvst
  • Spanning-tree extend system-id
  • Vlan internal allocation policy ascending



  • Switchport mode access
  • Spanning-tree portfast




For more in-depth information, please review the following references: