[c-nsp] Receiving out of order packets in SPAN session on Catalyst 3750X

[Steve Teti]

On 2015-03-19 9:21 AM, Phil Mayers wrote:
> That's kind of odd. 0.2ms on that kind of loading makes it surprising
> there's reordering. Where *is* that packet for 0.2ms?
> 
> I was wondering if it was a port asic grouping / buffering thing, with
> packets from other ports on  the SPAN ports own ASIC arriving "early",
> but the times and bandwidths, gut feeling says not.
> 
> Odd.

On the one specific example that I was able to capture, the out-of-order 
exchange is happening between two machines on Gi1/0/12 and Gi1/0/14 
(same port ASIC group I think?).  The monitor destination port is 
Gi2/0/10, the other switch in the stack.

I haven't ruled out the possibility that the capture server is actually 
reordering the packets somehow.  The capture server has two NICs 
connected to two different SPAN sessions.  The two NICs are bonded with 
Linux ethernet bonding, mode 3 (broadcast).  The out-of-order packets 
show up when capturing on the bond0 interface and the physical ethX 
interface.  I think I'm going to have to try removing the bond 
configuration completely and just capturing on the one physical 
interface.