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IDProjectCategoryView StatusDate SubmittedLast Update
000677510000-014: PubSubSpecpublic2021-04-06 13:202021-06-09 17:54
ReporterMatthias Damm Assigned ToMatthias Damm  
PrioritynormalSeverityminorReproducibilityhave not tried
Status closedResolutionfixed 
Summary0006775: Enhance description for max message size in UDP and ETH
Description

MaxNetworkMessageSize is defined as:
The MaxNetworkMessageSize with DataType UInt32 indicates the maximum size in bytes for NetworkMessages created by the WriterGroup. It refers to the size of the complete NetworkMessage including padding and signature without any additional headers added by the transport protocol mapping. If the size of a NetworkMessage exceeds the MaxNetworkMessageSize, the behaviour depends on the message mapping.

For ETH we define:
For OPC UA Ethernet the MaxNetworkMessageSize and the DiscoveryMaxMessageSize plus additional headers shall be limited to an Ethernet frame size of 1522 Byte.

For UDP we define:
For OPC UA UDP the MaxNetworkMessageSize plus additional headers shall be limited to 65535 Byte.

If somebody does not read this carfully, he may take the numbers as MaxNetworkMessageSize.
In addition the max for UDP is 65536 Byte.

Additional Information

We should provide a typical max calculation as example or note.

ETH
22 Byte header: DestAddress (6) + SrcAddress (6) + optional VLAN Tag (4) + EtherType (2) + FCS (4)).
MaxNetworkMessageSize = 1500 (1522 max frame size - 22 header)

UDP:
IPv4:
Max: 65,508 bytes (65,536 − 8 byte UDP header − 20 byte IPv4 header)
MTU: 1472 Bytes (1500 − 8 byte UDP header − 20 byte IPv4 header)
IPv6:
Max: 65,488 bytes (65,536 − 8 byte UDP header − 40 byte IPv6 header)
MTU: 1452 Bytes (1500 − 8 byte UDP header − 40 byte IPv6 header)

TagsNo tags attached.
Commit Version
Fix Due Date

Activities

Matthias Damm

2021-06-07 15:48

developer   ~0014480

Added notes to OPC 10000-14 - UA Specification Part 14 - PubSub 1.05.0 Draft33.docx

OPC UA UDP:

Note: The MaxNetworkMessageSize that fits into one MTU is typically 1472 Byte for IPv4 and 1452 Byte for IPv6. The additional headers have a size of 22 Byte for Ethernet, 20 Byte for IPv4 or 40 Byte for IPv6 and 8 Byte for UDP.

OPC UA Ethernet:

Note: The MaxNetworkMessageSize is 1500 Byte since the additional headers have a size of 22 Byte and it consists of 6 Byte destination address, 6 Byte source address, 2 Byte EtherType, 4 Byte frame check sequence and optionally 4 Byte VLAN tag.

Jim Luth

2021-06-09 17:54

administrator   ~0014533

Agreed to note added in Virtual F2F.

Issue History

Date Modified Username Field Change
2021-04-06 13:20 Matthias Damm New Issue
2021-04-06 15:24 Matthias Damm Additional Information Updated
2021-04-06 15:25 Matthias Damm Additional Information Updated
2021-04-06 15:26 Matthias Damm Additional Information Updated
2021-04-13 16:29 Jim Luth Assigned To => Matthias Damm
2021-04-13 16:29 Jim Luth Status new => assigned
2021-06-07 15:48 Matthias Damm Status assigned => resolved
2021-06-07 15:48 Matthias Damm Resolution open => fixed
2021-06-07 15:48 Matthias Damm Note Added: 0014480
2021-06-09 17:54 Jim Luth Status resolved => closed
2021-06-09 17:54 Jim Luth Fixed in Version => 1.05
2021-06-09 17:54 Jim Luth Note Added: 0014533