Requested revision
Standard: | 802.1CB-2017 | Clause: | 9.1.5.1 |
Clause title: | tsnCpeIpIdDestMac |
Rationale for revision
IP Stream identification (clause 6.7) is focused on layer 3 "streams". As such it uses the IP Destination Address to identify the stream. It also requires a MAC address to be specified as well.
I would suggest that replacement equipment that is going to be swapped in will likely have its IP address assigned to it before it is swapped in, but it’s MAC address will (almost) never match.
Here's my justification: a Pro Audio system controller expects every device in that system to have a unique IP address. If a device fails, its replacement is assigned the same IP address so the controller can find, monitor, and configure it. Therefore, when using IP addressing, it is often the case that the IP address is as unique to a device as is the MAC DA. Forcing the bridges in this failure case to be reconfigured for the new MAC DA when replacement equipment in installed (since that is currently required in CB-2017) seems to put an unnecessary burden on system management. Just let them swap in a new end station.
See slide 16 of http://www.ieee802.org/1/files/public/docs2019/maint-cgunther-CBitems-0519-v01.pdf for details about required vs optional parameters associated with IP Stream identification.
Suggestion is to make the destination MAC address optional. Note that the IP Destination address is still required.
Proposed text
Add a second sentence to this clause that says: "A value of 0 indicates that the destination_address of the packet is to be ignored on packets received from lower layers."
The wording of this sentence uses similar language regarding "ignored if zero" that is used with other parameters in 9.1.5 subclauses.
We may also want to add a note about why it may be important to also specify the MAC DA in certain cases, even though it is now an optional parameter.
Impact on existing networks
MAC DA was required and any systems that used this feature would have defined the MAC DA. IP Stream identification will still work exactly as before in systems that used IP Stream identification from CB-2017.
Originator
Name: | Craig Gunther | Email: | craiggunther@yahoo.com |
Affiliation: | Craig Gunther Consulting/Bosch | ||
Submitted: | 2019-05-17 |