Re: WAN conntivity problem

sagittarius · ‎05-10-2004

Hi,

We have a in-house developed software which is connected on LAN. Through LAN, access is very fast and through WAN it becomes very slow. When we try accessing it through LAN, the application opens in 5 seconds, but when we try to access it through WAN it takes 3-4 minutes.

We have 256kbps links to other offices (Channelised E1, 32*64 Kbps). We have divided it into 7 timeslots.

Following is the type of connectivity.

LAN --->Firewall-->WAN Router1----256Kbps--->WAN Router2

When i try to ping (ping 10.10.10.20 -l 32000) from application server to any machine i get a good response, but when i try to ping to firewall it goes only till 15000 bytes. Also, when i ping from WAN router1 to WAN router2 it is able to ping with 18024 bytes (limit for cisco router). Firewall we are using is netscreen. What could be the problem ?

smif101 · ‎05-10-2004

Ok first of all why are you trying to ping at a rate over the standard MTU of 1500 bytes. All traffic coming from the application server will be under 1500 bytes unless you set the MTU to something higher which I would recommend for you to change it back. In any case how large is the file from the application server that is downloaded from the server to the client. Is it a database of some kind? If it is a 5Meg file and 10 users from the remote side all try to download it at the same time then that would take around 4 minutes each. I would check to see what the utilization is of the WAN links to see if they are oversubscribed. If they are then you might just have to put another application server at the remote site. The same problems happen when you try to have a bunch of users logon to a Windows domain over a WAN link.

Jason Smith

www.smif101.com

sagittarius · ‎05-10-2004

We have fiber connectivity from Database server to Application server. Jumbo frame is enabled on both machines and also on switch. Firewall which connects to WAN is also on the same segment, will this effect the application. Cos application server will be send the data to the client machines at branch office and firewall/router is not capable to handle the same. Do i need to change the MTU value on Router/Firewall.

smif101 · ‎05-11-2004

Well I wouldn't enable jumbo frames unless that was required for the database. But if you want jumbo frames to be enabled then everything on that segment needs to be at the same MTU size otherwise it will drop the packet if it is to large. Another thing is when that jumbo packet gets to a D/E router and jumbo frames are not enabled there then the packet will be fragmented down to the MTU size of that segment. So what is the size of the database file that is sent over the WAN link.

Jason Smith

www.smif101.com

sagittarius · ‎05-11-2004

Now i am planning to have 2 NIC on the Application server. Database Server will be conected to the application server via a fiber cable1 and User's will access this server using another fiber cable2. I will enable jumbo frames on App/Database segment and for other card i will keep the frame size to 1500. So users will access this server via fiber cable2.

I checked the utilization on WAN link it show only 50-70% utilization when i open my application, but still the application is very slow. We have 256Kbps lease line from Branch offices(11) and a channalized E1 at Head Office. Router,Firewall and WANnlink are the components between.

smif101 · ‎05-12-2004

One other thing is do you have the bandwidth command issued on the interfaces to accuratly reflect the bandwidth that is on the line. If you don't then your utilization % will be off on the router. So again back to the Application server, how much DATA in BYTES is required for a user to download to open up this application at the desktop? Another question is how much delay is there between sites? If the size and delay is small, then I would try implemting QoS on the WAN links to allow priority traffic from the Application server.

Jason Smith

www.smif101.com

sagittarius · ‎05-13-2004

Ideally one session utilizes 16Kbps link at other office. I am not sure of the bytes that it is sends. At this office i tried access from only one machine, but still the performance was bad.

When i ping i get >10 ms response. I think the link is not a problem. I also changed the network card setting on server and desktops to 100Mbps/full-duplex mode.

Qos, sure i am going to implement but after i solve this problem.