We have a bottleneck between two points on our net. It is somewhere between three switches, a dell 5324 and two 3024's. The middle 3024 is acting as a relay becaues we are over 100 Meters between the two outer switches. The middle 3024 has a VLAN setup with just two ports assigned, 5 and 6. All connections copper (CAT5e). I should also state the fact that I set none of this up and can't reach (and don't want to reach) the person who did. So it looks like this:
5324<---------><5>3024<6><--------->3024
Please check my math and troubleshooting thoughts:
The two outer switches are default config with all ports in the default vlan. I have eliminated tham as a cause by moving the CAT5 cable to another port. The middle switch has 4 of these two-port VLANS config'd, so I was easily able to eliminate them as the cause by moving the patch cables to a different VLAN.
Math:
100 Mbs should = 12.5 MBs (divide bits by 8 to get bytes)
I understand in reality there is some overhead and we might see closer to 10 MBs or a little less. Let's be conservative and say 8 for half duplex.
So, if I drag and drop an 8 GB file across this line as a test, it should take 8GB divided by the 8 MBs for a 1000 second transfer time, right? Div by 60 is around 16 minutes.
After 5 and weekends this line is very lightly used. I can't immagine there is 10% of the bandwidth used, so we should be able to get that file across in 20 or 30 minutes, don't you think? I'd even give it an hour and say I'm wrong on the usage, but the file is taking hours and hours. I think there is a serious problem.
There is plenty more that I can try for troubleshooting, including using different lines. I am mainly concerned with my calculations and expectations of a 100 Mbs Ethernet, not how to troubleshoot. But there are a couple of other symptoms I observed I will mention, in case someone says, oh, yup, you have this or that wrong, idiot jon.
One thing is port 5 on the middle 3024 glows yellow. The manual says that means it is running at 10 Mbs, which would explain things. It may well be, and that would probably be bad wiring (I will eliminate or isolate that by substitution Monday night). However, the configuration of the middle 3024 says it's running 100 Mbs half duplex. I believe the configuration I am reading, quoted below, is a reading, or should I say a report of what was autonegotiated by the switch, and not a setting. Am I right? Does anyone know if it is running at 10 as the lamp indicates or 100 as config does? BTW: When I moved the patch cables from port 5 and 6 to an unused VLAN on ports 1 and 2, the yellow light followed the wiring.
Then on the 3024 on the end, I noticed in the config, all ports are set to auto negotiate, except the port the problematic line leads to, which has been manually set to 100 half duplex. I'm thinking this is an indication that someone saw a problem and was working with it, but gave up. I suppose the setting could cause some sort of a problem, but you should be able to set it up manually without a problem, except the predictable slower simpelx mode. I did try autonegotiate when I moved the line to another port for troubleshooting.
Anyone who read this far, thank you for putting some time and thought into this, regardless of weather or not you are able to understand my mumblings and provide an answer!
Cheers,
jon
5324<---------><5>3024<6><--------->3024
Please check my math and troubleshooting thoughts:
The two outer switches are default config with all ports in the default vlan. I have eliminated tham as a cause by moving the CAT5 cable to another port. The middle switch has 4 of these two-port VLANS config'd, so I was easily able to eliminate them as the cause by moving the patch cables to a different VLAN.
Math:
100 Mbs should = 12.5 MBs (divide bits by 8 to get bytes)
I understand in reality there is some overhead and we might see closer to 10 MBs or a little less. Let's be conservative and say 8 for half duplex.
So, if I drag and drop an 8 GB file across this line as a test, it should take 8GB divided by the 8 MBs for a 1000 second transfer time, right? Div by 60 is around 16 minutes.
After 5 and weekends this line is very lightly used. I can't immagine there is 10% of the bandwidth used, so we should be able to get that file across in 20 or 30 minutes, don't you think? I'd even give it an hour and say I'm wrong on the usage, but the file is taking hours and hours. I think there is a serious problem.
There is plenty more that I can try for troubleshooting, including using different lines. I am mainly concerned with my calculations and expectations of a 100 Mbs Ethernet, not how to troubleshoot. But there are a couple of other symptoms I observed I will mention, in case someone says, oh, yup, you have this or that wrong, idiot jon.
One thing is port 5 on the middle 3024 glows yellow. The manual says that means it is running at 10 Mbs, which would explain things. It may well be, and that would probably be bad wiring (I will eliminate or isolate that by substitution Monday night). However, the configuration of the middle 3024 says it's running 100 Mbs half duplex. I believe the configuration I am reading, quoted below, is a reading, or should I say a report of what was autonegotiated by the switch, and not a setting. Am I right? Does anyone know if it is running at 10 as the lamp indicates or 100 as config does? BTW: When I moved the patch cables from port 5 and 6 to an unused VLAN on ports 1 and 2, the yellow light followed the wiring.
Unit 1 Port Manager
Port Link Admin State Rate/Duplex Flow Ctrl Comments
--------------------------------------------------------------------------------
1 Down Enabled Blocking (Auto ) (Auto ) Not Defined
2 Down Enabled Blocking (Auto ) (Auto ) Not Defined
3 Up Enabled Forwarding (100 Full) (Enabled ) Not Defined
4 Up Enabled Forwarding (100 Full) (Enabled ) Not Defined
5 Up Enabled Forwarding (100 Full) (Enabled ) Not Defined
6 Up Enabled Forwarding (100 Half) (Disabled) Not Defined
7 Up Enabled Forwarding (100 Full) (Enabled ) Not Defined
8 Up Enabled Forwarding (100 Full) (Enabled ) Not Defined
9 Down Enabled Blocking (Auto ) (Auto ) Not Defined
10 Down Enabled Blocking (Auto ) (Auto ) Not Defined
11 Down Enabled Blocking (Auto ) (Auto ) Not Defined
12 Down Enabled Blocking (Auto ) (Auto ) Not Defined
<SNIP>
Then on the 3024 on the end, I noticed in the config, all ports are set to auto negotiate, except the port the problematic line leads to, which has been manually set to 100 half duplex. I'm thinking this is an indication that someone saw a problem and was working with it, but gave up. I suppose the setting could cause some sort of a problem, but you should be able to set it up manually without a problem, except the predictable slower simpelx mode. I did try autonegotiate when I moved the line to another port for troubleshooting.
Anyone who read this far, thank you for putting some time and thought into this, regardless of weather or not you are able to understand my mumblings and provide an answer!
Cheers,
jon