It is actually a 4001i for an IBM Blade Chassis. Sorry for that.
So in this setup, port a would be a trunk with multiple vlans
connection back to a 6509. port b would be a switch port in access
mode that connects to an IBM blade in the chassis.
Not sure that this situation fits either of those scenarios.
Overall problem is that we are seeing performance issues between
servers. These servers are all AIX based. We believe/know that we have
some misconfigurations in the environment with jumbo frames and flow
control. My curiosity about the discards is due to those
misconfigurations. The port I mentioned in my original email has
around 480 million output packes to the 1.1 million discards.
We do have IBM and Cisco support engaged, I am just trying to make
sure I understand enough to be dangerous when I am working with them.
Robert
On Thu, 27 Mar 2014 12:55:46 -0400
Lee <[email protected]> wrote:
On 3/27/14, [email protected] <[email protected]> wrote:
So I certainly admit I am a basic networking guy and in the past
have not
had to get into the nitty gritty of port statistics.
I am trying to understand some statistics off a switch port in a
Nexus
4001i.
Good luck. I couldn't find anything for a nexus 4000, but did find
this for IOS:
In-Discard - The result of inbound valid frames that were discarded
because the frame did not need to be switched. This can be normal if
a
hub is connected to a port and two devices on that hub exchange
data.
The switch port still sees the data but does not have to switch it
(since the CAM table shows the MAC address of both devices
associated
with the same port), and so it is discarded. This counter can also
increment on a port configured as a trunk if that trunk blocks for
some VLANs, or on a port that is the only member of a VLAN.
so if you've got something like
switch a: switchport trunk allowed vlan 1-5
switch b: switchport trunk allowed vlan 1-4
when switch a sends a frame on vlan 5, switch b counts it as an
input discard.
Lee
All TX and RX counters look normal except on the TX side, I am
showing 1107597 input discards. Last clearing of show counters is
1d8h ago.
I have it in my mind that this particular counter is dropping
packets coming
in from another port inside the switch that are to be transmitted
out to the
end server.
So lets say the interface I am looking at is port 2 on the switch.
So server
1 sends a packet to port 1 on the switch. That packet then traverses
to
backplane, or inside the same ASIC, to port 2 on the switch. It is
then
dropped and not transmitted out to server 2.
Is the scenario I just presented correct? Not looking for the reason
in this
email, just that my logical understanding is correct.
Robert
Sent from my Verizon Wireless 4G LTE smartphone
