User profile for user: johnnyjackhammer
johnnyjackhammer Author
User level: Level 1
110 points

Question on Networking Two Macs Using 10G Thunderbolt Adapters and No Switch

Hope someone with networking skills can provide some background here. The idea is to setup an additional 10G network for file transfers between the iMac and Mac Mini (with connected Thunderbolt RAID storage). My existing 1G network is using 192.168.10.x / 255.255.255.0 which is used for the internet connection for the entire network, routers, switches, wifi, Macs, iGadgets, etc..


Situation:

I have two new Thunderbolt to Ethernet 10G adapters, an Intel iMac, and an M2 Mac Mini. The adapters are connected using a Cat6 ethernet cable. I tried to manually set up Static IP addresses but failed. So I rebooted them both and both macs' services were auto-configured using DHCP.


However, I would like to understand why it's set up the way it is, and why the auto generated network services are different on the Intel iMac vs the Mac Mini?


Working configuration

Intel iMac was configured like so:


Thunderbolt Ethernet Slot 1:

  Type:	Ethernet
  Hardware:	Ethernet
  BSD Device Name:	en4
  IPv4 Addresses:	169.254.7.96
  IPv4:
  Additional Routes:
  Destination Address:	169.254.7.96
  Subnet Mask:	255.255.255.255
  Addresses:	169.254.7.96
  Configuration Method:	DHCP
  Confirmed Interface Name:	en4
  Interface Name:	en4
  Subnet Masks:	255.255.0.0
  IPv6:
  Configuration Method:	Automatic
  Ethernet:
  MAC Address:	00:24:27:09:09:85
  Media Options:	Full Duplex, Flow Control
  Media Subtype:	10Gbase-T
  Proxies:
  Exceptions List:	*.local, 169.254/16
  FTP Passive Mode:	Yes
  Service Order:	1


And if I look in Virtual Interfaces I see this setup:



The first odd thing being I would presume to choose "Thunderbolt Ethernet Slot 1" which coincidently was automatically created when initially plugging in the 10G adapter.



Moving on to the auto-configured setup on the Mac Mini...


Ethernet Adapter (en4):

  Type:	Ethernet
  Hardware:	Ethernet
  BSD Device Name:	en4
  IPv4:
  Configuration Method:	DHCP
  IPv6:
  Configuration Method:	Automatic
  Ethernet:
  MAC Address:	f6:36:b8:85:49:95
  Media Options:	
  Media Subtype:	none
  Proxies:
  Exceptions List:	*.local, 169.254/16
  FTP Passive Mode:	Yes
  Service Order:	2

Ethernet Adapter (en5):

  Type:	Ethernet
  Hardware:	Ethernet
  BSD Device Name:	en5
  IPv4:
  Configuration Method:	DHCP
  IPv6:
  Configuration Method:	Automatic
  Ethernet:
  MAC Address:	f6:36:b8:85:49:96
  Media Options:	
  Media Subtype:	none
  Proxies:
  Exceptions List:	*.local, 169.254/16
  FTP Passive Mode:	Yes
  Service Order:	3

Thunderbolt Ethernet Slot 1:

  Type:	Ethernet
  Hardware:	Ethernet
  BSD Device Name:	en6
  IPv4 Addresses:	169.254.21.150
  IPv4:
  Additional Routes:
  Destination Address:	169.254.21.150
  Subnet Mask:	255.255.255.255
  Addresses:	169.254.21.150
  Configuration Method:	DHCP
  Confirmed Interface Name:	en6
  Interface Name:	en6
  Subnet Masks:	255.255.0.0
  IPv6:
  Configuration Method:	Automatic
  Ethernet:
  MAC Address:	00:24:27:09:09:87
  Media Options:	Full Duplex, Flow Control
  Media Subtype:	10Gbase-T
  Proxies:
  Exceptions List:	*.local, 169.254/16
  FTP Passive Mode:	Yes
  Service Order:	1


And if I look in Virtual Interfaces I see this setup:


The Questions:


What I noticed right away is that the Mac Mini has three services setup en4, en5, en6. Whereas the Intel iMac only has the one service en4. So, thinking these were cruft leftover from my first attempt and unnecessary I removed them using Terminal... 


networksetup -deletepppoeservice "Ethernet Adapter (en4)" 
networksetup -deletepppoeservice "Ethernet Adapter (en5)" 


and rebooted...and they came back, so obviously they are required. Why the difference between the services automatically created on the Intel iMac vs the Apple M2 Mac Mini?


Next question is why was I unsuccessful in trying to set these up using a different subnet manually and if I wanted to do so how would I go about doing it?


I tried static addresses.... 192.168.9.1 / 255.255.255.0 and 192.168.9.2 / 255.255.255.0 for the adapters instead of DHCP. The way it's been configured it appears that both adapters are on different subnets - contrary to what I have read which says they need to be on the same subnet to talk to each other.


Thanks for ANY insights

Mac mini

Posted on Sep 28, 2023 4:45 PM

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10 replies
User profile for user: johnnyjackhammer
johnnyjackhammer Author
User level: Level 1
110 points

Sep 29, 2023 10:32 AM in response to MrHoffman

Thanks for your help MrHoffman! Now static IPs are working after a few corrections.


For the record (in the unlikely event someone else finds this useful) there are some requirements to set the adapters up manually that might not be immediately apparent to neophytes. I am not sure if I am using the correct terminology... apologies.


Choose "Thunderbolt Ethernet Slot 1" when creating a new service not "Thunderbolt Bridge" even though it shows up later in "Manage Virtual Interfaces" as "Thunderbolt Bridge"... who knows.


Clicking on "Manage Virtual Interfaces" we see some details of this interface


The interfaces to select are the physical computer ports you want to use for the physical adapter.


Choose "Manually" and choose an IP address subnet. My existing LAN is "192.168.10.x" so I chose "192.168.5.x" The mistake I made was I chose the wrong Subnet mask initially. It should be "255.255.0.0" not "255.255.255.0"


The next oversight was the settings in "Proxies". If you don't add the newly created IP address/subnet in CIDR format the services won't work. So...


I think I added that IP/subnet combo correctly using 192.168.5/8 ?


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User profile for user: MrHoffman
MrHoffman
User level: Level 10
146,443 points

Sep 29, 2023 6:08 AM in response to johnnyjackhammer

johnnyjackhammer wrote:

An oxymoron?


The interface is configured to use and trying to use DHCP, and is failing to contact a DHCP server.


I’d use IP over TB as linked earlier, or set up 10 GbE switch with DHCP and the rest, as unmanaged 10 GbE switches are becoming available at not-gonzo prices. (Having just installed some, managed 2.5 GbE, 5 GbE, and 10 GbE are more expensive than unmanaged, but less costly than in years past.)


But if this works back-to-back, have at.


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User profile for user: MrHoffman
MrHoffman
User level: Level 10
146,443 points

Sep 29, 2023 11:07 AM in response to johnnyjackhammer

So long as you’re using different IP subnets for configurations where IP routers separate the IP network segments involved (and as is the case with the two network segments discussed here), things will work. And you’re probably aiming for a /24 there, not an /8.


Network proxies are not involved here.


I usually use switched IPv4 and DHCP or IPv6 networks, with a mix of static addresses as needed (for accounting purposes, usually “reserving” the static IP in the DHCP server via MAC address), and variously with local DNS server(s) configured for the private hosts. APs for Wi-Fi. Bridging, proxies, or such, less often.

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User profile for user: johnnyjackhammer
johnnyjackhammer Author
User level: Level 1
110 points

Sep 29, 2023 12:08 PM in response to MrHoffman

Network proxies are not involved here.


what are the default proxies in a new interface? Is 169.24/16 always included and if not can I remove that?


Also, the Mac mini still show three services while the iMac shows on the one. Why would this be. I have tried to remove en4 and en5 but they come back.



Ethernet Adapter (en4):

  Type:	Ethernet
  Hardware:	Ethernet
  BSD Device Name:	en4
  IPv4:
  Configuration Method:	DHCP
  IPv6:
  Configuration Method:	Automatic
  Ethernet:
  MAC Address:	f6:36:b8:85:49:95
  Media Options:	
  Media Subtype:	none
  Proxies:
  Exceptions List:	*.local, 169.254/16
  FTP Passive Mode:	Yes
  Service Order:	2

Ethernet Adapter (en5):

  Type:	Ethernet
  Hardware:	Ethernet
  BSD Device Name:	en5
  IPv4:
  Configuration Method:	DHCP
  IPv6:
  Configuration Method:	Automatic
  Ethernet:
  MAC Address:	f6:36:b8:85:49:96
  Media Options:	
  Media Subtype:	none
  Proxies:
  Exceptions List:	*.local, 169.254/16
  FTP Passive Mode:	Yes
  Service Order:	3

Sabrent TB3 Ethernet Adapter:

  Type:	Ethernet
  Hardware:	Ethernet
  BSD Device Name:	en6
  IPv4 Addresses:	192.168.5.0
  IPv4:
  Additional Routes:
  Destination Address:	192.168.5.0
  Subnet Mask:	255.255.255.255
  Destination Address:	169.254.0.0
  Subnet Mask:	255.255.0.0
  Addresses:	192.168.5.0
  Configuration Method:	Manual
  Confirmed Interface Name:	en6
  Interface Name:	en6
  Subnet Masks:	255.255.0.0
  IPv6:
  Configuration Method:	Automatic
  Ethernet:
  MAC Address:	00:24:27:09:09:87
  Media Options:	Full Duplex, Flow Control
  Media Subtype:	10Gbase-T
  Proxies:
  Exceptions List:	*.local
  FTP Passive Mode:	Yes
  Service Order:	1



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User profile for user: johnnyjackhammer
johnnyjackhammer Author
User level: Level 1
110 points

Sep 30, 2023 10:54 AM in response to MrHoffman

It was working quite well, but now the transfers are going over en0 instead of en4 and I am realizing I need a way to force transfers over this 10G connection. Changing the service order has not had an affect.


Is there a way to setup which NIC to use for Internet and which to use for LAN connections?


I have some ideas but don't know how to implement them


routes

ioctl
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Question on Networking Two Macs Using 10G Thunderbolt Adapters and No Switch

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