Gigabit port throughput limits

Unanswered Question
Jul 23rd, 2009
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Hi everyone!


I run a network powered by 3750G. Network consists of several points of presence with several switches in each. POPs are xconnected with fibers.


I hvanoticed that some fiber ports start to loose packets on low bitrate (100M). Closer inspection showed that packet rate is much bigger (40000 Pps).


I found it accaptable since nature of data is multicast with packets of 500-700 bytes average.


For most of ports packet loss starts when PPs reaches ~83000. While there is a port where I see packet loss on 40k in each direction.



So I have two questions:


1. Is it a practical top of switch port throughput ? Looks weird when switch looses packets on 100Mbps utilisation;


2. My understanding is that Tx and Rx are woring with its own buffers each. Thus overflow of one of them shouldn't impact the other. But practically I see that Tx and Rx packet rates are affecting buffer in total.


I'm starting to feel like something is misconfigured. Please advice.


Alex.


H2H

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aspodinets Thu, 07/23/2009 - 12:49
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Here is the summary of the port for #2:

show interfaces gi1/0/25 summary


*: interface is up

IHQ: pkts in input hold queue IQD: pkts dropped from input queue

OHQ: pkts in output hold queue OQD: pkts dropped from output queue

RXBS: rx rate (bits/sec) RXPS: rx rate (pkts/sec)

TXBS: tx rate (bits/sec) TXPS: tx rate (pkts/sec)

TRTL: throttle count


Interface IHQ IQD OHQ OQD RXBS RXPS TXBS TXPS TRTL

-------------------------------------------------------------------------

* GigabitEthernet1/0/25 0 0 0 1676612 44711000 36148 74959000 35788 0


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