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The FAQs listed below are for these products:

  • J4812A HP ProCurve Switch 2512
  • J4813A HP ProCurve Switch 2524
  • J4817A HP ProCurve Switch 2312
  • J4818A HP ProCurve Switch 2324
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Auto-negotiation
» Q: Is 10/100Mbps auto-negotiation the same as Plug-n-Play?
» Q: Is Gigabit Ethernet auto-negotiation the same as Plug-n-Play?

Cabling
» Q: How does the HP Auto-MDIX feature work? What products support this feature?
» Q: Can I use category 3 cables with the HP ProCurve Switch 100/1000Base-T Transceiver?
» Q: What is the maximum length for cables used with the HP ProCurve Switch 100/1000Base-T Transceiver?

General
» Q: How can I set the time or date?

Features
» Q: What are the differences between the HP ProCurve Switch 2512 (product number J4812A) and the HP ProCurve Switch 212m (product number J3298A)?
» Q: What are the differences between the HP ProCurve Switch 2524 (product number J4813A) and the HP ProCurve Switch 2424m (product number J4093A)?
» Q: What are the differences between the HP ProCurve Switch 2324 (product number J4818A) and the HP ProCurve Switch 2224 (product number J4095A)?
» Q: What transceiver modules are supported on the HP ProCurve Series 2300 and 2500 switches? Are the supported transceiver modules "hot-swappable?"
» Q: When I start a console session on my new ProCurve Networking by HP Series 2500 switch, I get the prompt "HP ProCurve Switch 2524#." How do I access the menu interface?
» Q: What function does the "download port" of the HP ProCurve Networking Series 2300 switch provide?

Spanning tree protocol
» Q: When STP is configured off, do the Switch 2512 and Switch 2524 forward STP bridge protocol data units (BPDUs) that they receive?
» Q: Do the ProCurve Networking by HP Series 2500 switches send 802.1Q tagged STP BPDUs out tagged ports?
» Q: What should I do if my switch (which has switched ports to the desktop) reports many Spanning Tree Protocol (STP) topology changes, even if I am not having connectivity problems?
» Q: Why is my Macintosh system unable to use AppleTalk services?

Troubleshooting
» Q: How can I troubleshoot problems when my Apple devices (iMac, PowerMac, Mac II, etc.) cannot access the network through my ProCurve Networking by HP switch?
» Q: Why won't my Xircom Realport-REM56G-100BTX Notebook NIC operate properly with my ProCurve Networking by HP switch in full duplex mode at 100Mbps?
» Q: When I connected my new HP ProCurve Series 2500 switch to my HP ProCurve Switch 4000m using a Gigabit-SX or Gigabit-LX connection, the link did not come up. Why not?
» Q: Using HP Hub & Switch Management for OV-UX (product number J3250N), how can I get the close-up view of my HP ProCurve Switch 2512 or 2524?
» Q: Why won't my iMac, which is directly attached to an ProCurve Networking by HP switch, NetBoot from an OS X Server, even though it worked correctly when my iMac was plugged directly into a hub?
» Q: Why is my Macintosh system unable to use AppleTalk services?

VLANs
» Q: How can the Series 2500 switches allow an IP address per VLAN, but only one default gateway?
» Q: By default, VLAN support on the ProCurve Networking by HP Series 2500 switches is enabled. Can you disable VLAN support like you can on the Switch 4000m?
» Q: My HP ProCurve Series 2500 switch is configured with multiple VLANs and I want to use DHCP to learn its IP address and default gateway for each VLAN. Since the Series 2500 switches support a single global default gateway, which of the DHCP supplied default gateway addresses will the switch use?
» Q: What is the recommended way to connect multiple VLANs between a routing switch and a layer 2 switch?

Answers

Q: What is the recommended way to connect multiple VLANs between a routing switch and a layer 2 switch?
The diagram below illustrates the question.

VLAN Diagram A

The following HP switches provide VLANs and have a single MAC/Ethernet address (filtering) table: Switch 800t, 2000, 1600m, 2400m, 2424m, 2512, 2524, 4000m, 8000m. In the diagram above we show a Switch 2500, but the following discussion applies to all of the switches listed in the previous sentence. The ProCurve Networking by HP Routing Switch 9304m, 9308m, or 6308m-SX, as a default gateway, has a single MAC address (for all of its VLANs) if using virtual Ethernet interfaces. In the diagram above we show a 9304m, but this could be a 9308m or 6308m-SX as well.

Let's consider PC "A" attempting to send an IP packet to PC "B". PC "A" will send the 2500 a packet with the 9304m's MAC address in the destination field. If the 2500 has not yet learned this MAC address, the 2500 will flood the packet out all of its VLAN1 ports, including the VLAN1 link to the 9304m. The 9304m will then route the packet toward PC "B" via its link with the 2500's VLAN2 connection. The 2500 will enter the 9304m's MAC address into its MAC address table as located in VLAN2. The 2500 will also forward the packet to PC "B".

Let's consider a second packet that PC "A" sends to PC "B". PC "A" sends the packet, again addressed to the 9304m's MAC address, to the 2500. The 2500 will check its address table and find that the 9304m appears to be located on VLAN2. Since the 2500 believes that this MAC address is not located on VLAN1, the switch will discard the packet.

Later, when the 9304m transmits a packet to the 2500 via the VLAN1 link, the 2500 will update its address table to indicate that the 9304m's MAC address is located in VLAN1 instead of VLAN2. As you can see, the 2500's location information for the 9304m's MAC address will vary over time between VLAN1 and VLAN2. For this reason, some packets directed through the 2500 for the 9304m's MAC address will be discarded. Performance may appear to be poor or connectivity may appear to be broken.

To avoid this issue, simply use one cable between the 2500 and the 9304m instead of two, making sure that the two VLANs use tags on that link, as shown below.

VLAN Diagram B

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Q: What should I do if my switch (which has switched ports to the desktop) reports many Spanning Tree Protocol (STP) topology changes, even if I am not having connectivity problems?
STP was developed to manage switch-to-switch links, or bridge-to-bridge links as they were initially called. For most of STP's lifetime, a topology change was a serious event as it indicated a change in the LAN topology. It also indicated a likelihood that STP had to bring (at least) a portion of the LAN down for awhile in order to rebuild a new working topology. Of course, in a LAN we expect the topology to change only rarely.

Over the past few years, the cost of switch ports has dropped dramatically. Users can now afford to dedicate switch ports to end nodes.

Once an STP topology is stable, establishing an Ethernet link on a switch port results in a topology change. This happens every time a user powers up their PC (assuming that the PC is directly connected to a switch port), resets the PC, or brings up the PC's network stack. The establishment of this link causes the topology change count to increment in:

  1. the switch to which the end node is directly attached; and
  2. "upstream" switches. That is, the root switch and the switches between the root switch and the switch to which the end node is directly connected.

This scenario does not result in any topology issues or changes. It does not result in any loss of connectivity in the LAN. If the incrementing of your topology change count is due to this type of scenario, you do not need to take any action.

The above discussion applies to Hewlett-Packard switches in general and ProCurve Networking by HP switches in particular when configured in STP Normal mode. When an ProCurve Networking by HP switch's port is configured in STP Fast mode, the switch will not increment the topology change count as a result of link changes on that port. Please see the switch's Management and Configuration Guide for details on normal and fast modes.

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Q: Is 10/100Mbps auto-negotiation the same as Plug-n-Play?
No. The following configuration will cause severe network problems:

Node configuration diagram

The hub, switch, or router will correctly sense (not auto-negotiate) the 10Mbps or 100Mbps speed. Since the end node was configured for a specific speed and duplex state and therefore does not negotiate, the hub, switch, or router will choose the communication mode specified by the 802.3u standard, namely half-duplex.

With one device running at half-duplex and the device on the other end of the connection at full-duplex, the connection will work reasonably well at low levels of traffic. At high levels of traffic the full-duplex device (end node, in this case) will experience an abnormally high level of CRC or alignment errors. The end users usually describe this situation as, "Performance seems to be approximately 1Mbps!" Often, end nodes will drop connections to their servers.

In this same situation, the half-duplex device will experience an abnormally high level of late collisions.

The network administrator must take care to verify the configuration of each network device during installation. Also, check the operational mode of each network device. That is, check both how you configured it and also that it comes up as you expect, for example, at 10Mbps/half-duplex.

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Q: Is Gigabit Ethernet auto-negotiation the same as Plug-n-Play?
No. By the time the IEEE issued the 802.3z specification, they knew about the 10/100Mbps auto-negotiation problem (see the FAQ "Is 10/100Mbps auto-negotiation the same as Plug-n-Play?"). To prevent it, 802.3z auto-negotiation requires that, if one side of a connection is configured to auto-negotiate, the other side must also auto-negotiate if the connection is to come up. In other words, if a switch is configured to auto-negotiate and its attached end node is configured to, say, 1000Mbps/full-duplex, the 803.2z spec requires that the switch NOT allow the link to come up.

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Q: Can I use category 3 cables with the HP ProCurve Switch 100/1000Base-T Transceiver?
No, only category 5 100-ohm UTP or STP cables are supported. In fact, for the most robust connections you should use cabling that complies with the Category 5E specifications, as described in Addendum 5 to the TIA-568-A standard (ANSI/TIA/EIA-568-A-5).

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Q: What is the maximum length for cables used with the HP ProCurve Switch 100/1000Base-T Transceiver?
The maximum length is 100 meters using category 5, 100-ohm UTP or STP cable. This distance is correct for the IEEE 802.3ab specification.

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Q: What are the differences between the HP ProCurve Switch 2512 (product number J4812A) and the HP ProCurve Switch 212m (product number J3298A)?
The HP ProCurve Switch 2512 has 12-fixed 10/100Base-T RJ-45 ports with two transceiver slots supporting Gigabit-SX, Gigabit-LX, 100/1000Base-T, 100-FX SC and Gigabit Stacking transceivers. The HP ProCurve Switch 212m has 12-fixed 10 Mbps RJ-45 ports with one transceiver slot supporting 10/100Base-T or 100Base-FX connectivity and one fixed 10/100Base-T RJ-45 port.

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Q: What are the differences between the HP ProCurve Switch 2524 (product number J4813A) and the HP ProCurve Switch 2424m (product number J4093A)?
The HP ProCurve Switch 2524 has 24-fixed 10/100Base-T RJ-45 ports with two transceiver slots supporting Gigabit-SX, Gigabit-LX, 100/1000Base-T, 100-FX SC and Gigabit Stacking transceivers. The HP ProCurve Switch 2424m has 24-fixed 10/100Base-T RJ-45 ports with one module slot supporting Gigabit-SX, Gigabit-LX, 100/1000Base-T, 100-FX SC and Gigabit Stacking transceivers.

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Q: What are the differences between the HP ProCurve Switch 2324 (product number J4818A) and the HP ProCurve Switch 2224 (product number J4095A)?
The HP ProCurve Switch 2324 is an unmanaged switch that has 24-fixed 10/100Base-T RJ-45 ports with two transceiver slots supporting Gigabit-SX, Gigabit-LX, 100/1000Base-T, 100-FX SC and Gigabit Stacking transceivers. The HP ProCurve Switch 2324 also provides a "download" port for future software upgrades. The HP ProCurve Switch 2224 is an unmanaged switch that has 24-fixed 10/100Base-T RJ-45 ports with one transceiver slot supporting 100Base-FX connectivity.

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Q: What transceiver modules are supported on the ProCurve Networking by HP Series 2300 and 2500 switches? Are the supported transceiver modules "hot-swappable?"
The following transceiver modules are supported for the Series 2300 and 2500 switches:

  • ProCurve Networking by HP Gigabit-SX Transceiver (J4131A)
  • ProCurve Networking by HP Gigabit-LX Transceiver (J4132A)
  • ProCurve Networking by HP 100-FX SC Transceiver (J4853A)
  • ProCurve Networking by HP 100/1000-T Transceiver (J4834A)
  • The transceivers that are part of the ProCurve Networking by HP Gigabit Stacking Kit (J4116A)

Transceiver modules can be inserted into the switch while it is powered on. However, the switch must be rebooted to activate the transceiver. For more information, refer to chapter 2 of the ProCurve Networking by HP Series 2300 and 2500 Switches Installation and Getting Started Guide.

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Q: How does the HP Auto-MDIX feature work? What products support this feature?
HP Auto-MDIX is a feature on all 10/100Base-TX ports of the ProCurve Networking by HP Series 2300 and 2500 switches. When configured in the default configuration "AUTO", the switch automatically detects the signaling on the cable from the connected device and operates as either an MDI or MDIX port. As a result, a "straight-through" twisted-pair cable can be used; you no longer have to use "crossover" cables, although "crossover" cables can also be used for any of the connections. The following devices support the HP Auto-MDIX feature:

  • Fixed 10/100Base-T ports of the Switch 2512 and 2524 (J4812A and J4813A)
  • Fixed 10/100Base-T ports of the Switch 2312 and 2324 (J4817A and J4818A)
  • 100/1000-T Transceiver module (J4834A)

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Q: By default, VLAN support on the HP ProCurve Series 2500 switches is enabled. Can you disable VLAN support like you can on the HP ProCurve Switch 4000m?
No. VLAN support cannot be disabled on the HP ProCurve Series 2500 switches. By default, all ports are configured in the default VLAN (DEFAULT_VLAN). The following table shows the differences between the HP ProCurve Switch 4000m, 8000m, 1600m, 2424m and 2400m and the HP ProCurve Series 2500 switches with respect to VLAN support:

FeatureSwitch 4000m, 8000m, 1600m, 2424m and 2400mSwitch 2512 and 2524
VLAN Support optionsDisable (default)
Enable
Always enabled
(cannot disable)
Default VLANCan change VIDCannot change VID

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Q: My ProCurve Networking by HP Series 2500 switch is configured with multiple VLANs and I want to use DHCP to learn its IP address and default gateway for each VLAN. Since the ProCurve Networking by HP Series 2500 switches support a single global default gateway, which of the DHCP supplied default gateway addresses will the switch use?
The Series 2500 switches will use the DHCP information received for the VLAN configured as the "Primary VLAN". In the factory-default configuration, the switch designates the default VLAN (DEFAULT_VLAN) as the "Primary VLAN". However, you can designate another VLAN as the "Primary VLAN" using the "Primary VLAN" configuration option. For more information, refer to chapter 9 of the ProCurve Networking by HP Series 2500 Switches Management and Configuration Guide.

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Q: When I start a console session on my new ProCurve Networking by HP Series 2500 switch, I get the prompt "HP ProCurve Switch 2524#." How do I access the menu interface?
The default interface for the ProCurve Networking by HP Series 2500 switches is the Command Line Interface (CLI). The CLI is a full-featured interface that can be used to get status information (show commands) and perform configuration changes (configuration context). To access the menu interface, issue the command "menu" from the CLI. Also, using the "setup" command from the CLI or menu interface allows you to configure most of the basic options on the switch such as IP addressing and passwords.

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Q: When I connected my new ProCurve Networking by HP Series 2500 switch to my HP ProCurve Switch 4000m using a Gigabit-SX or Gigabit-LX connection, the link did not come up. Why not?
The ProCurve Networking by HP Gigabit-SX module used in the HP ProCurve Switch 4000m, 8000m, 1600m, 2424m and 2400m is set by factory-default to "1000 Fdx" whereas the factory-default setting for the ProCurve Networking by HP Gigabit-SX transceiver used in the ProCurve Networking by HP Series 2300 and 2500 switches is "Auto". The configuration must be set to match on both ends to provide Gigabit connectivity.

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Q: What function does the "download port" of the ProCurve Networking by HP Series 2300 switch provide?
This port is used to connect a PC to the switch using a "null modem" cable. This connection can then be used to initiate a download of new software to the Series 2300 switch. New software may be available if there are any product enhancements, such as the support of new transceiver modules. For more information, refer to chapter 1 of the ProCurve Networking by HP Series 2300 and 2500 Switches Installation and Getting Started Guide.

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Q: Why won't my iMac, which is directly attached to an ProCurve Networking by HP switch, NetBoot from an OS X Server, even though it worked correctly when my iMac was plugged directly into a hub?
This issue is not specific to HP switches. Rather, it is a timing problem in early versions of the iMac Boot ROM. Apple Computer, Inc has fixed this NetBoot issue by releasing both an updated Boot ROM image and Mac OS X Server version 1.2. Please advise customers with iMac NetBoot issues to contact Apple Computer, Inc Technical Support.

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Q: Why is my Macintosh system unable to use AppleTalk services?
Possible symptoms include: no AppleTalk services, only local network AppleTalk services, performance problems, and intermittent network services. If you remove the Macintosh from its dedicated switch (or routing switch or router) port and connect it to a hub, the problem goes away.

If the switch (or routing switch or router) has Spanning Tree Protocol enabled, see Apple Computer, Inc's Tech Info Library entry "Spanning Tree Protocol: AppleTalk and NetInfo Issues".

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Q: When STP is configured off, do the Switch 2512 and Switch 2524 forward STP bridge protocol data units (BPDUs) that they receive?
Yes. Note that the Switches 1600m, 2400m, 2424m, 4000m, and 8000m do not forward STP BPDUs when STP is configured off in those switches.

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Q: How can I set the time or date?
Use the global configuration mode time command in the Command Line Interface.

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Q: Using HP Hub & Switch Management for OV-UX (product number J3250N), how can I get the close-up view of my HP ProCurve Switch 2512 or 2524?
HP Hub & Switch Management for OV-UX, version N, displays these devices as generic icons. Double-clicking on these icons does not bring up the close-up view. You can use either of the following two workarounds.

  1. You can get the close-up view by entering the switch's IP address into the URL line (Internet Explorer uses the label "Address", while Netscape Communicator calls it "Location:") of a web browser. The supported browsers and versions are listed in the Management and Configuration Guide for the HP ProCurve Switch 2512 and 2524, in the chapter "Using the HP Web Browser Interface", section "Web Browser Interface Requirements".
  2. Configure Network Node Manager to bring up the switch's TELNET interface when double-clicking on the icon. To do this, perform the following steps:
  • right-click on the switch icon
  • from the menu, choose Symbol Properties
  • set Behavior to Execute
  • set Application Action to Terminal Connect: Xterm TELNET
  • click on Target Objects
  • for Additional Objects, click Add
  • click OK
  • click OK

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Q: Why won't my Xircom Realport-REM56G-100BTX Notebook NIC operate properly with my ProCurve Networking by HP switch in full duplex mode at 100Mbps?
HP knows that this Xircom NIC, at full duplex over 100Mbps, does not operate with our ProCurve Networking by HP switches. HP has no reports of any other vendors' NIC having a similar issue with our ProCurve switches. While this NIC's data sheet states support of full duplex, HP has not been able to get this NIC to operate at full duplex over a 100Mbps connection, regardless whether it is configured to Auto-negotiate or full duplex, fixed configuration.

We are not aware of any fixes for this issue.

Failure symptoms include poor performance and lost connections. See the discussion of "Q: Is 10/100Mbps auto-negotiation the same as Plug-n-Play?" on this same page for more details on the problem symptoms.

The workaround is to operate the NIC in half-duplex mode or to use a different NIC.

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Q: Do the ProCurve Networking by HP Series 2500 switches send 802.1Q tagged STP BPDUs out tagged ports?
No. These switch models implement single-instance STP and so their STP BPDUs are always untagged, regardless of the switch's configuration. For more information, see the ProCurve Networking by HP Series 2500 Switches Management and Configuration Guide's chapter on "Configuring Advanced Features", section "Effect of VLANs on Other Switch Features", subsection "Spanning Tree Protocol Operation with VLANs".

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Q: How can the Series 2500 switches allow an IP address per VLAN, but only one default gateway?
Click here to view the pdf file that contains the answer to this question.

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