Gigabit port throughput limits

aspodinets · ‎07-23-2009

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

aspodinets · ‎07-23-2009

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