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Re: [802.3_SPEP2P] Number of link segment in-line connectors

Steffen,

 

Thanks for this. a couple of things spring to mind:

  1. With existing 10BASE-T1L being 10 connectors over a 1000m, I assume the model is the connectors/surge protectors at each end, and 8 connectors in the middle with 100m nominal distances between them.
  2. If this is the case, then it seems that we are OK with 10 “connectors” (really connecting devices) in 10BASE-T1L and so 5 should be find for a 500m 100BASE-T1L line.
  3. On this general topic, it seems like maybe we should get some more info on “deployment considerations”. I’m wondering how common surge protectors and similar devices will be in deployments. Is it the case that these are “normally” deployed? Does this factor into the link segment in any other ways?

 

Regards
Peter

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From: Steffen Graber <steffen@xxxxxxxxxxxxx>
Sent: Tuesday, June 29, 2021 12:55 AM
To: STDS-802-3-SPEP2P@xxxxxxxxxxxxxxxxx
Subject: [802.3_SPEP2P] Number of link segment in-line connectors

 

Dear all,

 

during our last meeting we discussed in the SPE enhancements study group the question about how many in-line connectors will be needed for a maximum length link segment.

 

While I agree that one in-line connector per 100 m link segment length is a good choice, I recommend to increase the overall number of allowed in-line connectors per link segment by an additional two connectors, allowing to substitute these two in-line connectors by Ethernet-APL auxiliary devices. In Ethernet-APL up to two auxiliary devices (typically surge protectors) can be added, while reducing the number of allowed in-line connectors by one per auxiliary device.

 

This is very similar to adding a PoE midspan PSE, which can be installed instead of one of the connection pairs in the floor distributor, as described in clause 33.4.9. Allowing for two additional in-line connectors in this context would also allow to use (potentially future defined) PoDL midspan devices being able to “upgrade” unpowered SPE switches by adding an external power coupling/decoupling circuit.

 

Just allowing e.g. 5 in-line connectors for a 500 m link segment, this would result in just having 3 remaining in-line connectors in applications, which use surge protection or future midspan PoDL devices, which would be 1 connector per 167 m only and thus require pretty long cable runs between two in-line connectors. Going for up to 7 in-line connectors (5 + 2) for a 500 m link segment would bring us back to the 1 in-line connector per 100 m range.

 

Best regards,

 

Steffen Graber

 

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