Switches

Requirements 

Bandwidth 

The switch needs to support the bandwidth needed for the respective application. Lawo recommends

  • 1GB Ethernet for J2K video applications and for pure audio applications
  • 10GB Ethernet for video applications and mixed audio / video applications, including 4K using VC-2 compression
  • 40GB Ethernet for the V__matrix, also supporting uncompressed 4K video applications

QoS

The switch must support DiffServ (RFC2474) and traffic prioritization according to IEEE802.1p.

Spanning tree

The switch must support Rapid Spanning Tree (RSTP) or Multiple Spanning Tree (MSTP) as defined in IEEE802.1w or IEEE802.1s respectively.

PTP 

The switch should support PTP as defined in IEEE1588-2008 with at least E2E Transparent Mode, preferably also Boundary Clock mode.

The switch shall also support settings for all necessary PTP parameters to comply with the SMPTE ST2059-2 and AES-R16-2016 profiles.

 

Multicast 

The switch must support multicast traffic (RFC 1112)

The switch must support multicast forwarding

The switch must support IGMPv2 (RFC 2236)

The switch must support IGMP snooping (RFC 4541)

The switch should support report flooding or the manual configuration of mrouter ports

 

Performance 

The switch must meet the following performance characteristics:

  • Non-blocking: The switch must use a non-blocking architecture, meaning that the switch internal forwarding capacity is equal to the capacity of a single port times the number of ports (e.g. a 48 port 10GbE switch needs 48*10Gb*2 (full duplex) = 960Gb/s switching capacity)
  • Support for enough multicast groups: The switch must support as many multicast groups as you intend to send streams plus another 20 groups for management traffic (PTP, IGMP messages, etc). If you intend to use TR03 / ST2110 compliant setups, bear in mind that each signal will be transported as separate audio, video and data streams. 1024 multicast groups are a reasonable starting point for smaller setups
  • The switch may not lose IGMP messages, even when operating under high load
  • IGMP processing time: the faster, the better. This directly correlates with the number of program switches that a system will be able to perform per time unit. See the “IGMP Performance” section above for an example
  • Port to Port latency (10Gb): 5µs
  • PTP accuracy for PTP-aware switches: less than 1µs

 

Settings 

These settings should be applied to switches in order to make them work correctly:

  •  Multicast / IGMP

    • Enable IGMP Snooping
    • Disable IGMP Fast Leave (aka Immediate Leave) unless the complete system has been tested and proven to work with this setting
    • Enable IGMP Querier and set IGMP Querier version to 2
    • Set the querier IP address to the IP of the switch (if needed)
    • Enable report flooding or manually define the mrouter ports (or disable the querier in the V__line)
    • Filter all unregistered / unknown multicast traffic

  • QoS

    • Enable accepting (“trusting”) DSCP values on the ingress interfaces
    • Enable correct mapping of DSCP values to internal (IEE802.1p) CoS queues

  • Miscellaneous

    • Disable power management on all ports (Green Ethernet, Energy Efficient Ethernet)
    •  Disable Jumbo Frames

  • PTP

    • Enable PTP
    • Set PTP to Boundary Clock mode (if available and proven to work correctly) or E2E Transparent mode as a fallback

  • Spanning Tree

    • Enable Rapid Spanning Tree
    • Set all ports that are connected to devices (as opposed to other switches) to “Portfast” with BPDU Guard enabled (Note: the V__link4/V__remote4 contains a switch. The respective ports should NOT be set to Portfast).

Some of these settings might need to be applied to individual ports or VLANs. Consult your switch manual for details.

 

Limitations 

The following features are not supported at this time, either because they are known not to work or because they have not been sufficiently tested:

  • Link aggregation
  • PIM routing for video streams (testing pending)
  • IGMP version 3
  • Network Address Translation (NAT)
  • Tagged VLANs

 

Switch models 

The following switches have successfully been used in Lawo deployments:

  • Cisco SG300 [discontinued]: Audio, non PTP
  • Cisco Catalyst 3750X [discontinued]: Audio, non-PTP
  • Cisco Catalyst 3650: Audio, non PTP
  • Cisco Nexus 3000 Series: Audio, Video, selected models PTP
  • Cisco Nexus 9000 Series: Audio, Video, PTP (boundary clock; observe compatibility with Cisco DCNM if network control is desired)
  • Cisco Industrial Ethernet 4010: Audio, PTP (E2E, Boundary Clock)
  • Extreme Networks X460 Gen 2: Audio, PTP
  • Hirschmann Mach 104: Audio, PTP
  • Artel Video Systems ARG Quarra (formerly ARG, formerly “Stagebox”): Audio, PTP (E2E, Boundary)
  • Arista Networks 7150: Video, PTP (E2E, Boundary), Report Flooding
  • Arista Networks 7280: Video, PTP (E2E), Report Flooding
  • Arista Networks 7500 Series: Video, PTP (E2E), Report Flooding

 

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