RE: Network Lag on Cisco? [7:70648]
It's time to do some troubleshooting. Although the 3600 and 2600 routers aren't considered high-end routers, they nonetheless shouldn't cause a noticeable delay if they are correctly configured with a simple config. If you're doing a bunch of access lists and NAT and other CPU-intensive stuff on them, then maybe they would cause a delay, but, in general, they shouldn't be noticeably slower than a Linux server acting as a router, depending of course, on the CPU and RAM on the Linux server. Check for errors on your routers and switches. Start at the lowest layer and move up. I agree with Mark that you may very well have a duplex mismatch somewhere in the network. Look for CRC errors and collisions. Also check that you are using 100 Mbps, not 10 Mbps. If you are using 10 Mbps and utilization is high, move to 100. Check for routing protocol issues. When problems occur, is BGP confused about routes? In your case (as opposed to your friend's case), it doesn't sound like you've ruled out the server as being the problem. Put Ethereal on your computer and watch what happens. Sometimes you can easily see proof that the network isn't slow, but the server is. This proof comes in the form of quick TCP ACKs, with no data in them. The network must be fast if you can quickly receive an ACK, but the ACK is empty because the server application is slow. TCP is fast, but the application is slow and doesn't have any data ready to piggy-back onto the ACK. I can recommend a good book on troubleshooting! :-) Try Troubleshooting Campus Networks. Good luck. Keep us posted! Thanks. ___ Priscilla Oppenheimer www.priscilla.com Anil Gupte wrote: > > Our network is running a 3640 as a core router and several > other smaller > routers plus an HP Procurve for the Servers and LAN. We run > BGP across two > upstream networks. Now, for a long time we have had a slight > lag on our > network. For example, whenever I am logged into our Linux > servers, I will > be typing something and I will lose the cursor, then suddenly a > bunch of > letters will appear at the cursor. There are other examples. > We have > hunted up and down and not found a problem/solution. > > Now comes the interesting part. A friend of mine who has been > running Linux > for years used a Linux machine as a router for the last 3.5 > years. At my > urging he decided to try a Cisco because his server was getting > old and > needed an overhaul. Yesterday he did and now has the same > problem. His > config is very simple - he has a 2640 router running IOS 12.1 - > one T-1 and > one Ethernet port to which he has connected his Dialup > equipment (he is a > Dialup ISP). > > What gives? He is now bad mouthing Cisco even more than he did > before! > > Any ideas appreciated. > Thanx, > Anil Gupte > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=70656&t=70648 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Network Lag on Cisco? [7:70648]
Anil- I'll try to take a stab at this... For your network: Verify that you are not experiencing packet loss on the uplink from your Procurve switch to the Cisco Router. Make sure you have the speed and duplex setting hard-coded on each end. Aside from that, I would look into congestion management, as you may need to implement CBWFQ on the Router (assuming that the telnet sessions have lag, and are having to cross the T1 circuit. I seriously doubt this would be the issue on the Ethernet/FastEthernet interface. In fact, if Telnet is lagging from inside the network and the only device that has to be crossed is the switch, I'd check the connection between the Linux box and the switch, as well as the Subnet Mask/Default Gateway to ensure those are set correctly. For the friend's network: See "aside from that,..." comment above. HTHs, Mark -Original Message- From: Anil Gupte [mailto:[EMAIL PROTECTED] Sent: Friday, June 13, 2003 10:28 PM To: [EMAIL PROTECTED] Subject: Network Lag on Cisco? [7:70648] Our network is running a 3640 as a core router and several other smaller routers plus an HP Procurve for the Servers and LAN. We run BGP across two upstream networks. Now, for a long time we have had a slight lag on our network. For example, whenever I am logged into our Linux servers, I will be typing something and I will lose the cursor, then suddenly a bunch of letters will appear at the cursor. There are other examples. We have hunted up and down and not found a problem/solution. Now comes the interesting part. A friend of mine who has been running Linux for years used a Linux machine as a router for the last 3.5 years. At my urging he decided to try a Cisco because his server was getting old and needed an overhaul. Yesterday he did and now has the same problem. His config is very simple - he has a 2640 router running IOS 12.1 - one T-1 and one Ethernet port to which he has connected his Dialup equipment (he is a Dialup ISP). What gives? He is now bad mouthing Cisco even more than he did before! Any ideas appreciated. Thanx, Anil Gupte Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=70653&t=70648 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Network Lag on Cisco? [7:70648]
Our network is running a 3640 as a core router and several other smaller routers plus an HP Procurve for the Servers and LAN. We run BGP across two upstream networks. Now, for a long time we have had a slight lag on our network. For example, whenever I am logged into our Linux servers, I will be typing something and I will lose the cursor, then suddenly a bunch of letters will appear at the cursor. There are other examples. We have hunted up and down and not found a problem/solution. Now comes the interesting part. A friend of mine who has been running Linux for years used a Linux machine as a router for the last 3.5 years. At my urging he decided to try a Cisco because his server was getting old and needed an overhaul. Yesterday he did and now has the same problem. His config is very simple - he has a 2640 router running IOS 12.1 - one T-1 and one Ethernet port to which he has connected his Dialup equipment (he is a Dialup ISP). What gives? He is now bad mouthing Cisco even more than he did before! Any ideas appreciated. Thanx, Anil Gupte Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=70648&t=70648 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
