SFP Module Compatibility

As I could end up in argueing with the provider, I wan’t to get the turris side properly cleared: While switching WAN from the providers “Fritzbox” towards “Turris Mox” I’m wondering how to recognize a “compatible” SFP Module.

The module gets recognized by the kernel as “mv88e6085 d0032004.mdio-mii:11 sfp”. After plugging it to the wall-connector the kernel logs the following (and more).

user@device:/tmp# grep sfp /var/log/messages
messages:335:May  1 06:23:29 tumox kernel: [    9.886468] sfp sfp: Host maximum power 3.0W
messages:378:May  1 06:23:29 tumox kernel: [   10.262124] sfp sfp: module T&W TW7251J-C1AL rev 1.01 sn 0686381AU        dc 160502  
messages:379:May  1 06:23:29 tumox kernel: [   10.270302] mv88e6085 d0032004.mdio-mii:11 sfp: switched to inband/1000base-x link mode
messages:404:May  1 06:23:29 tumox kernel: [   14.796745] mv88e6085 d0032004.mdio-mii:11 sfp: configuring for inband/1000base-x link mode
messages:406:May  1 06:23:29 tumox kernel: [   15.373095] mv88e6085 d0032004.mdio-mii:11 sfp: Link is Up - 1Gbps/Full - flow control rx/tx
messages:407:May  1 06:23:29 tumox kernel: [   15.381916] IPv6: ADDRCONF(NETDEV_CHANGE): sfp: link becomes ready or paste code here

Find an ethertool output for completeness below:

user@device:/tmp# /usr/sbin/ethtool -m sfp
	Identifier                                : 0x03 (SFP)
	Extended identifier                       : 0x04 (GBIC/SFP defined by 2-wire interface ID)
	Connector                                 : 0x07 (LC)
	Transceiver codes                         : 0x00 0x00 0x00 0x02 0x00 0x00 0x00 0x00 0x00
	Transceiver type                          : Ethernet: 1000BASE-LX
	Encoding                                  : 0x01 (8B/10B)
	BR, Nominal                               : 1300MBd
	Rate identifier                           : 0x00 (unspecified)
	Length (SMF,km)                           : 10km
	Length (SMF)                              : 10000m
	Length (50um)                             : 0m
	Length (62.5um)                           : 0m
	Length (Copper)                           : 0m
	Length (OM3)                              : 0m
	Laser wavelength                          : 1310nm
	Vendor name                               : T&W_____________
	Vendor OUI                                : 00:00:00
	Vendor PN                                 : TW7251J-C1AL____
	Vendor rev                                : 1.01
	Option values                             : 0x00 0x1a
	Option                                    : RX_LOS implemented
	Option                                    : TX_FAULT implemented
	Option                                    : TX_DISABLE implemented
	BR margin, max                            : 20%
	BR margin, min                            : 20%

Thanks for your valuable support.

1 Like

I am sure you should change topic to SFP module not LXC module😇


I’ll just drop a link:

(and I renamed the topic)


Thanks a lot for correcting my typo.

Regarding “read-the-docs”. I did. But …
The page mentioned

  • seems to reside within a document tree which has been declared as “outdated”;
  • itself provides no information on its timeliness.

A more intense study - a lot of people would label it “tldr;”, the hint on the “recent changes link” was found on another page.

Anyway - i’ll pick a compatible SFP Module from stock.

A hint for anyone who’s looking for more flexible SFP modules:

FLEXBOX with universal transceivers by https://www.flexoptix.net/

(indeed, for just one or a few modules it’s overkill)

With turris os 6.3.1 the SFP module “T&W TW7251J-C1AL rev 1.01” mentioned works like a charm.

More background: It is used within switzerland where the basic fiber infrastructure usually requires the SFP module parameters “Simplex or BiDi SFP with the wavelengths TX 1310nm/RX 1490nm and 10km line distance. In some swiss city networks autonegotiation must be switched off within the module”.

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