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Q: Why is my 100Base-T Hub 12txm (J3233A) or 100Base-T Hub 12tx (J3234A) experiencing resets or failed connections?
Situation
The auto-negotiation signals of some 100Base-T devices may cause the HP J3234A 100Base-T Hub-12tx and HP J3233A 100Base-T Hub-12txm to repetitively reset all its ports, possibly causing severe network disruption, failed connections, or abnormal LED behavior. This problem affects only the "A" version Hub-12txm and Hub 12-TX. It does not occur with the "B" version of those products (J3233B and J3234B).
This problem does not occur in the J3235A 100Base-T Hub-8txe or the J3272A 100Base-T Hub-24tx. This problem also does not occur in any HP 100Base-T switching products. These other hub and switch products all use different chip sets and different architectures, and therefore do not exhibit any of the problems associated with the "A" version of the Hub-12tx and Hub-12txm products.
Problem Symptoms
Reset activity is seen when a 100Base-T device is either first connected to the hub OR the device is powered on after being connected to the hub. The resets may cause the hub's LEDs to flash on and off and, in some cases, the resets can cause severe network disruptions and lost connections. Other symptoms may include performance degradation in some or all NICs.
Under what conditions does this problem occur?
The following list of NIC cards has been known to cause the above behavior. This is only the list of known NICs as of June 1998.
- HP D3999 Night Director NIC
- 3Com 3C905, revision A
- Farallon PN996TX
- Linksys LNE100TX
- Intel ProB 10/100 intergrated into motherboard of Toshiba Pentium II 233MHZ.
There may exist other NIC cards on the market today or in the future that cause these issues.
What to do if you encounter this problem
If you are using either the J3233A or J3234A, and are experiencing the described problems, or have any other concerns, please contact one of the following phone numbers for assistance in receiving replacement products (J3233B or J3234B).
When calling , please have the following information available:
- Product number(s) (J3234A or J3233A)
- Serial numbers
For worldwide assistance in local languages, please call your local HP Customer Care Center.
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Q: How do you connect two 100Base-T hubs together?
The connection method depends on whether the Fast Ethernet hub is a Class I or Class II hub.
- For the HP Advancestack 100Base-T Hub-8txe and the ProCurve Networking by HP 100Base-T Hub 8, which are Class II hubs, plug a straight-through cable from the MDI port on one hub to the MDI-X port on the other hub.
- For the HP Advancestack 100Base-T Hub-12tx and the HP Advancestack 100Base-T Hub-12txm, which are Class I hubs, only one single repeater is allowed. These hubs, however, can be stacked to allow up to five of these hubs in a stack.
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Q: How do I stack the Hub-12tx or Hub-12txm?
Included with your Hub-12 TX/TXM is a stacking cable. This cable will pass network and management traffic from hub to hub in the stack allowing all hubs to be managed by one managed hub. The managed hub is the Hub-12txm. You can stack five hubs because the stacking cable connects all ports in one collision domain.
For hub to hub connections, the Advancestack Hub-12-TX/TXM has two stacking connectors on the rear of the hub, one labeled IN and the other labeled OUT. To connect the hubs together, follow these steps:
- Be sure that one of the hubs in the stack is a Hub-12txm.
- Starting at the top of the stack, insert one end of the stacking cable into the OUT port and the other end into the IN port of the second hub. In the above illustration, notice that the stacking cable from the OUT port of Hub ID 1 is connected to the IN port of Hub ID 2.
- Repeat these steps for the remaining hubs.
In a stacked system, each hub should have a unique ID number to identify itself. Each hub automatically sets an ID number if attached to an SNMP management agent (i.e., Hu-12txm) through the stacking port. When a new hub is inserted in the stack, the next available hub identifier is assigned to the new hub (e.g., the identifier numbers are not changed for previously configured hubs).
After you have made these stack connections, follow these steps:
- Check that the Hub ID LED is lit and different for each hub in the stack. (If the Hub ID is not correct, see page 3-2 in the HP 100Base-T Advancestack Hub-12tx/TXM Installation and Reference Guide, and use the ASCII console for change.)
- Connect the 100Base-T port of your workstation, server, or printer to one of the other Hub-12 TX/TXM's in the stack.
- Check that the "Link/Traffic" LED for the port connected is lit.
- Test the connection by passing network traffic from your workstation to the server or printer.
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Q: How do I isolate a Hub-12tx or Hub-12txm in a stack?
Network traffic for the Hub-12 TX/TXM can be isolated from the Hub stack collision domain. The management traffic will continue through the stacking cable but not the network traffic. The benefits of isolation are security, troubleshooting, and finding the "top talkers".
To isolate a hub in a stack, follow these steps:
- Using network management software for the Hub-12txm, connect the console port from your PC to the console connector on the front of the Hub-12tx/TXM. If a Hub-TXM is in the stack, you can only manage the stack using the TXM console port.
- Use the Hub configuration screen in the VT-100 console interface to isolate a hub (for example, number five) from the other Hubs in the stack. Hub number five will be in its own collision domain.
- Check that the Isolated LED is lit on Hub number five.
- Connect your PC to Hub number one and the printer to Hub number five.
- Try to send Network traffic (or print) from your PC to Hub number five. This should not work because Hub five is isolated from the rest of the stack. If you cannot communicate with the isolated hub, then the hub was successfully isolated.
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Q: How do I connect workgroup devices to my Hub-12tx or Hub-12txm?
The Advancestack 100T Hub-12 TX/TXM has RJ-45 100Base-T shielded ports that allow you to connect to devices such as workstations, servers, and printers. To create a workgroup, follow these steps:
- Connect the 100Base-T port of your workstation, server, and printer to the Hub-12 TX/TXM using Category 5 UTP/STP cable.
- Verify that none of the cable lengths are more than 100 meters long.
- Check that the "Link/Traffic" LED for the device (server or printer) and the hub are both lit after the connection.
- Test the connection by passing network traffic from your workstation to the server or printer. If the files are not transferring (e.g., you can't print a file), verify that you have followed the steps above. Bad cables are common so replacing a cable is not unusual.
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Q: How do I connect the Hub-12tx or Hub-12txm to an HP Switch 800t?
The Advancestack Hub-12tx/TXM can be connected to an external Switch 800t. The maximum distance is 100 meters from the hub to the switch using the MDI port. The hub and switch connection improves performance because of two reasons:
- Adding switches to an existing network increases network diameter.
- Each hub is on its own collision domain and is no longer carrying traffic for all of the other hubs connected to it.
To improve your network, follow these steps:
- Connect port number 12mDI from each Hub to any port on the Switch 800t using RJ-45 TP Category 5 cable up to 100 m.
- For each hub connected to the Switch 800t, check that the "Link/Traffic" LED is lit on port 12.
- To prove that the connection between the switch and hub is working, retrieve and open a file from another server connected through the Switch 800t. For example, in the above illustration a manufacturing user would copy a file from the Engineering Server because the Switch 800t is between the user and the server.
- Using the VT-100 console connection, from the main menu of the Hub select Statistics, then Port Statistics.
- Verify that port 12 is operating correctly by checking to see if any errors occurred during transmission of files. If errors do occur and you have followed the above steps correctly, you may just have a bad cable. Try another cable.
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Q: How do I connect the Hub-12tx or Hub-12txm Switch Port Module to an HP Switch 800t?
The Advancestack Hub-12 TX/TXM Switch Port Module (TX or FX) can be connected to an external Switch 800t. The maximum distance for TX is 100 meters from the Hub to the Switch and 2 kilometers for FX with both ends set at full duplex. The Switch Port Module allows your network to increase the bandwidth to full duplex and connect groups between buildings with 2-kilometer fiber cable.
To connect ports on the Switch Port Module to the Switch 800t, follow these steps:
- In the Hub-12tx or Hub-12txm, there is Switch Port Module with a TX or FX port. Connect this port to the Switch 800t using Category 5 UTP/STP cable or fiber-optic cable, respectively.
- Check that the "Link/Traffic" and "FDX" LEDs are lit on the Switch Port Module.
- To prove that the connection between the switch and hub is working, retrieve and open a file from another server connected through the Switch 800t. For example, in the above illustration a manufacturing user would copy a file from the Engineering Server because the Switch 800t is between the user and the server.
- Using the VT-100 console connection, from the main menu of the Hub, select Statistics, then Port Statistics.
- Verify that the "Exp Port" is operating correctly by checking to see if any errors occurred during transmission of files. If errors do occur and you have followed the above steps correctly, you may just have a bad cable. Try another cable.
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Q: How do I connect a Fast Ethernet hub to a 10Base-T hub?
The HP Advancestack 100Base-T Hub-8txe and the ProCurve Networking by HP 100Base-T Hub 8 can only be directly connected to another Class II 100Base-T hub or to a switch. To connect them to a 10Base-T hub, either use a switch in between, or connect them to the ProCurve Networking by HP 10/100 Hub 12 or 12m or ProCurve Networking by HP 10/100 Hub 24 or 24m which are both Class II hubs that autosense the speed of each port to be either 10Mbps or 100Mbps.
For the HP Advancestack 100Base-T Hub-12tx and the HP Advancestack 100Base-T Hub-12txm, insert an optional HP Switch Port Module into one of the hubs. From the port on that module, you connect a Category 5 cable (or fiber-optic cable) to the 10Base-T hub.
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Q: What do the letter abbreviations mean in Hub-12txm and Hub-12tx mean?
Hub-12txm means 12 100Base-TX (twisted-pair ports) with built in management.
The Hub-12tx means 12 100Base-TX (twisted-pair ports) with no management.
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Q: How do I manage 100Base-T hubs?
The HP Advancestack 100Base-T Hub-8txe and the ProCurve Networking by HP 100Base-T Hub 8 are unmanaged hubs. The HP Advancestack 100Base-T Hub-12tx is manageable from the HP Advancestack 100Base-T Hub-12txm in the same stack. With one Hub-12txm in a stack of Hub-12tx devices, you can manage the entire stack using the VT-100 console interface or HP Toptools for Hubs & Switches.
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Q: How do I convert my 10Base-T workgroup of 10 users to a Fast Ethernet workgroup?
First, each cable between the hub and the end node must be 4-pair Category 5 cable with a maximum of 100 meters. Second, each PC needs either a 10/100T LAN adapter or a 100T LAN adapter. (See HP's LAN Adapters for more information.) After the cables and LAN adapters are changed, then remove the 10Base-T hub(s) and plug in the cables and power cord into the Fast Ethernet hub.
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Q: How can I connect my Fast Ethernet workgroup to the Internet?
Add an HP J3231A Remote 2C/HP Internet Router Bundle to your workgroup. This product has a 10Base-T port that will connect to the Switch Link port on the Hub-12txm or Hub-12tx.
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Q: How far apart can I keep my hubs?
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