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I have a Mac Pro connected to a Cisco switch. In the switch I've setup a PortChannel to use LACP (802.3ad) but don't know if macOS sets the bond to Active, Passive or On. Unable to find any technical documentation regarding this.

I set it to Active but don't know if that's the proper configuration. Having some odd connectivity issues losing access to "everything" intermittently. Started a ping from the Mac Pro to the LAN gateway IP and next time it drops, I'll see if it's lost Layer2 connectivity.

The Mac Pro is the DNS server and file server, so if there is something happening with Layer2 connectivity, I'd suspect this configuration first.

Dacid Salin
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  • Random things found via google seem to indicate you should use active, but other things state it only works with Apple equipment.... – djsmiley2kStaysInside Oct 03 '18 at 17:13
  • LACP is an industry standard protocol defined by IEEE 802.3ad. I had a conversation with Apple Enterprise Support and they were not certain what needed to be configured. – Dacid Salin Oct 03 '18 at 19:30

1 Answers1

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Apple's macOS (formerly MacOS) is based on BSD Unix. I looked at FreeBSD configurations and found this gem https://www.freebsd.org/doc/handbook/network-aggregation.html

I had initially set my switch interfaces as:

 interface GigabitEthernet0/47
  description *MAC PRO LACP*
  switchport mode access
  channel-protocol lacp
  channel-group 1 mode active
 !
 interface GigabitEthernet0/48
  description *MAC PRO LACP*
  switchport mode access
  channel-protocol lacp
  channel-group 1 mode active

I ran the IOS command to view the LACP neighbors 

Switch#sh lacp nei
Flags:  S - Device is requesting Slow LACPDUs 
        F - Device is requesting Fast LACPDUs
        A - Device is in Active mode       P - Device is in Passive mode     

Channel group 1 neighbors

Partner's information:

                  LACP port                        Admin  Oper   Port    Port
Port      Flags   Priority  Dev ID          Age    key    Key    Number  State
Gi0/47    SA      32768     003e.e1cb.71d4   7s    0x0    0x1    0x4     0x3D  
Gi0/48    SA      32768     003e.e1cb.71d4   7s    0x0    0x1    0x5     0x3D  
Switch#

Per the FreeBSD configuration, it's showing correctly with the flag set to SA. Still waiting to hear back from Apple Enterprise Support for confirmation.

Edit

One thing I find contradicting is one sets the switch ports to active, then the flags show the peer as SA, meaning the peer is Active.

Dacid Salin
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    Whether your switch is Active and whether your host is Active are unrelated to each other. **Both sides can be Active** without problem, this just means they'll both attempt to *start* the LACP negotiation upon connection. – u1686_grawity Oct 04 '18 at 16:51
  • Thanks @grawity. I just got that out of another conversation as well. – Dacid Salin Oct 04 '18 at 16:54