informations about network configuration in a client server environment

Well first thing is to prove that the problem is the network. Has that been done?  If so, how?

is it just for academic research or for a real enterprise environment?

nowadays most modern applications may be not running in typical or traditional C/S model hence the network topology, configuration and protection may be significantly different.

we better know more details for giving a more proper suggestion.

hello all,
it's for real enterprise environment... we have some issues (slowness, dhcp delay, ...) and I want to know deeper if some protocols are raising this strange behaviours..
thank you very much

Nick

> slowness

do you mean high latency for PING or file sharing between local computers?

> dhcp delay

do you mean local computers are failed or having difficulty to obtain an IP from the DHCP server?

do you mean high latency for PING or file sharing between local computers?

the ping seems ok, the file transfer (and all normal activity of an end user is quite slow (we tried with brand new computer and with old ones...)

do you mean local computers are failed or having difficulty to obtain an IP from the DHCP server?

yes exactly, we have issues in both PXE request and normal IP request (often the clint pc wont get the IP, but not always) .
This since we change the switches on the floors (HP 2920). On these switches I've enabled spanning tree option (default option) and configured static vlans, only


regards
Nick

how many VLANs does your network have? is there a central L3 switch doing routing?

the switches are all 1Gb, the client workstation same.
Normally when you browse a folder on the DFS or open a simple excel or word file (less than 1MB) it takes a long time (20 seconds to 1 minute)...
there is no VPN or any well-known bottleneck... we have 40 servers connected to a couple of HP 3800 switches (in stack) and all the fibers are connected to 2x HP 3800. Before we had a network 100Mb by Nortel and was worst (at least for the file transfer).
but the DHCP delay has been introduced by replacing the switches with the HP.

hope I've been clearer
regards
Nick

we have 34 VLANs, (5 VLANs for client PC, 1 for the servers and the rest for other segments).
the HP 3800 are doing the routing between VLANs

if all servers, especially file servers, are sitting in the same VLAN or subnet while most client computers on various VLANs ALWAYS access the centrally shared files on the servers via routing, the trunck connection could be a bottleneck especially if the connection has a single link.

from the floor switches to the core switches we have 2 HP3800 that are connected to the HP 3800 servers switches via 2 fibers of 10Gb. I could (if this could improve the performances, also stack these 2 switches with the other ones.
thank you again for your interest
Nick

I would start looking to make sure all interfaces are the same duplex.

Do you have any network management/monitoring tools?

If not I would suggest you get something to monitor link utilziation, drop packet/frames, ect.

That is the first angle try to eliminate all things "not normal".

Like duplex errors, or mis negotiated speeds.. check the logs for anomalies, unexpected cross links, loops etc.
Also check how big your VLAN's are, better have several smaller networks then one huge one.
A tool for testing effective bandwidth (across many platforms) is netio
http://www.ars.de/ars/ars.nsf/docs/netio

Try to get effective statistics on port level, first on trunks later on all ports.
and try to identify bottlenecks.  cacti is a nice tool for this
   http://www.cacti.net/

Also last but certainly not least.
Make a drawing of your network for layer 2 and one layer 3.
And map the network topology on the real world topology.
Not as you want it to be, but based on info you find on the equipment. MAC tables, comments in config, routing tables, then compare it to the desired network and identify hotspots...

I'm looking at the netio and cacti (actually I was using Observer).
but someone has some whitepapers on best practice on how to configure a network?

thank you again
Nick

Most boil down to these:

Choose a valid design for your network (logical) so that all functionality required can be provided. Then translate that to a physical setup.
In general choose the simple design (KISS).  
Dynamic / auto configurations also leaves a possibility with misconfiguration. esp. is equipment from various vendors is used. So static infra cables can be static setup, whereas your endpoints can also be dynamic if needed [ think wired laptops f.e. ].

Hunt down all errors on links (errors cause retransmissions ==> delays). [ collisions are not errors on Half Duplex lines ]  
lines should be balanced, [ both sides of a cable the same, speed, duplex, etc. ].

if new equipment is needed, choose manageable equipment over "auto" configuring devices [ hubs/switches].

thank you very much... I was guessing me too if LACP on the core switches introduced a delay... (at least it seems on the 4 nics of the dfs server)...
Right now I've installed cacti and I'm studying how to shows the correct informations I want...

well lacp isn't introducing a delay, but under heavy traffic the negotiation frames for keeping the LACP live might get dropped, if a one to many gets dropped the LACP will dissolve and needs to be re negotiated again.

Help yourself by making this a fixed etherchannel (cisco) / Team / Bond / Trunk(hp)
even in a fixed setup one failing line won't be used. no need to use the auto configuring stuff for this.

Ok, so I'll dissolve the LACP and I will create a Trunk...
thank you very much

thank you all for your replies