lan performance baseline

carl_townshend · ‎11-18-2008

Hi all, I have been running some packet sniffing on my lan, as people complain of degraded performance, there are around 150 pc's on each vlan. what kind of packets per second would be an average baseline for normal network operation.

Also what is the best thing to look for in Wireshark using the stats etc

Many thanks

Carl

ropethic · ‎11-19-2008

PPS per second is really dependent on the model of switch. Cisco determines maximum packets per second based on 64 byte packets so it can be a bit misleading.

What I would look for:

1. Check CPU on swicthes / routers

2. Perform trace routes to / from different VLANs to determine avg latency

3. From wireshark, look for retransmisisons to check for dropped packets.

4. Avg Utilization

5. Avg packet size

6. check uplinks for dropped / discarded packets, crc, alignment errors (duplex mismatch)

7. Is there one particular host on the vlan sending bulk of traffic

8. Virus conditions - dos, syn, smurf attacks

You cna download filters from wireshark to check for these conditions.

9. is there a particular time of day this occurs? backups being done during business hours

10. any changes to the network recently? when did the problem start occurring?