FreeBSD 10-stable (r274577) LACP / IEEE 802.3ad with TP-Link TL-SG2008 - not working

[David P. Discher]

On Dec 15, 2014, at 11:33 AM, Alan Somers <asomers at freebsd.org> wrote:

> On Sun, Dec 14, 2014 at 6:23 PM, David P. Discher <dpd at dpdtech.com> wrote:
>> 
>> So, I think I’ve identified the issue.  In sys/net/ieee8023ad_lacp.c, lacp_pdu_input() has a sanity check :
>> 
>>        if (m->m_pkthdr.len != sizeof(*du)) {
>>                goto bad;
>>        }
>> 
>> I added some debugging information in if_lagg, and ran with it.  The lacpdu packet that being sent by the TP-Link switch is 4 bytes longer than the FreeBSD "struct lacpdu du”.
>> 
>>        em1: lacp_pdu_input-sizeof(du) bad m_pkthdr.len=128 sizeof(du)=124
>> 
>> My packet captures shows the packet size differing as well.
>> 
>> I’m still poking around. I’ve been trying to look for the official LACPDU binary/wire format … if someone can point me to the reference for that, that would be helpful (at least my own understanding).
> 
> Try here:
> http://standards.ieee.org/findstds/standard/802.1AX-2008.html
> 

Thanks - I hadn’t seen the “free” version from IEEE, and may looking into that later.  However, I think my time with messing around with this switch and lagg is just about over. 

I did get FreeBSD to work with LACP in this Switch.  I hacked in the 4 extra bytes in struct lacpdu in src/sys/net/ieee8023ad_lacp.h

Index: ieee8023ad_lacp.h
===================================================================
--- ieee8023ad_lacp.h	(revision 275779)
+++ ieee8023ad_lacp.h	(working copy)
@@ -151,6 +151,7 @@
 	struct lacp_collectorinfo ldu_collector;
 	struct tlvhdr		ldu_tlv_term;
 	uint8_t			ldu_resv[50];
+	uint8_t			tplink[4];
 } __packed;

 /*


This work great and without any issue.  All the defaults with 10-stable (r275778) and recent version of -head with this one line made it work.  Of course, this will likely break FreeBSD with all other switches LACP.

However, what I have also discovered this this switch is unlike FreeBSD which lagghash includes L4, the switch only seems to hash over SRC+DST IP or SRC+DST MAC.  Which makes it pretty much just sends all the traffic down one link from the switch. So for my particular use case with a small set of hosts, this switch is not useful for me.

I would not recommend the TP-Link TL-SG2008 8-Port Gigabit Smart Switch for use with FreeBSD … or for any use with LACP that is expecting increased throughput for a small set of hosts. 


-
David P. Discher
http://davidpdischer.com/
AIM: DavidDPD | Y!M: daviddpdz