Manaf,
Your rate may be fine depending on packet size, for example 65 byte
frames are less efficient in the hardware path and buffers than 64
bytes. You wouldn't expect more than about 760Mb/s in the best case
with that size frame. With no congestion and one continuous input,
9000B frames can achieve about 990Mb/s.
So, the question here: is this a problem or an observation? What rate
do you expect? Has anything changed? Let's see if you have drops, also
if you have CPU-switched flows, that will cause noticeable latency and
will limit throughput. Sniffing the traffic may show retransmissions,
which would mean drops occur somewhere in the path.
The only thing you can do at this point, without changing the traffic
flows (or can you?) is to look at drops and adjust buffer settings if
desired.
For dropping traffic, you can look at "show int gi 5/2" and see if Total
output drops is increasing.
Also look at "show queueing interface gi 5/2" and at the bottom you
should see packets dropped on transmit and dropped on receive. See if
these are incrementing.
Finally, if you are getting software drops somewhere on input, you need
to look at all other L3 interfaces that could possibly send traffic here
(including this one) for input queue drops in software:
"sh int | inc is up|queue"
Interesting output would look like this:
...
TenGigabitEthernet2/3 is up, line protocol is up (connected)
Input queue: 3/2000/189/15 (size/max/drops/flushes); Total output drops:0
...
TenGigabitEthernet2/3 is up, line protocol is up (connected)
Input queue: 18/2000/264/16 (size/max/drops/flushes); Total output
drops: 0
Notice how drops and flushes have incremented here, indicating
congestion to the software path (CPU punt). There are many reasons
traffic might be punted, but let's see if that's the case first.
Regards,
John Gill
cisco
On 10/4/11 5:49 AM, Nick Hilliard wrote:
On 04/10/2011 07:38, Manaf Al Oqlah wrote:
Normal Configuration:
interface GigabitEthernet5/2
ip address x.x.x.x
no ip redirects
no ip proxy-arp
media-type rj45
MTU is default 1500
The GE ports on a VS-S720-10G-3C supervisor are each provisioned with 9.6MB
RX and 8.1MB TX buffers. This is quite a respectable amount of buffer
space for a GE port, although if you have mls qos enabled, the default TX
configuration is 1p3q4t, configured as:
SP: 1.2MB
Q3: 1.2MB
Q2: 1.6MB
Q1: 4.1MB
This may not suit your traffic profile if everything is in a default
priority class, as you'll end up putting everything into q1.
reference paper:
http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_white_paper09186a0080131086.html
Nick
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