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Q: When I power on my PC, I get the message "a file server could not be found". How do I fix that?
This is a well-known issue given the following situation:
- The PC is directly-connected to a switch
- The PC is running Novell's VLMs or Client32
- The switch has Spanning Tree Protocol (STP) enabled
In this situation, when the directly-connected PC is powered on, the switch senses linkbeat on that port. This causes the switch to go through the four Spanning Tree states: blocking, listening, learning, and forwarding. It takes 30 seconds for the switch to complete that sequence and begin forwarding packets to and from that port. During those 30 seconds, Novell sends 3 requests for a server, then stops looking. By the time Spanning Tree completes its job, Novell reports that "a file server could not be found".
There are several workarounds available:
- Disable Spanning Tree on the switch (if Spanning Tree
is not needed, i.e. no loops in the network topology).
- For VLMs, add a "pause" just after calling VLM.EXE in
STARTNET.BAT. When the user reboots a PC, have them wait
at least 30 seconds before continuing the sequence. This
workaround is documented on Novell's Knowledgebase (www.support.novell.com,
search for document 2920460).
- For Client32, add a registry entry in the PC, as documented
on Novell's Knowledgebase (search for document 2925582).
In the Fall of 1998, HP released switch firmware (version A.01.25 or later) with an enhancement to resolve this timing problem between Novell and STP. The enhancement allows users to configure Spanning Tree so that it does not go through the 4 states, on a port-by-port basis. Instead, for those configured ports, Spanning Tree will immediately begin forwarding packets to and from the port. This allows Novell clients to communicate with the server as soon as the network card (NIC) is enabled. After that, the switch continues to listen for and send Spanning Tree packets on those configured ports. This protects the user who might inadvertently connect a hub or switch to that port and create a network loop - Spanning Tree will detect the loop after a short time, since the port listens for and sends STP packets on that port.
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Q: What cables are used with the HP Advancestack Switch 208t and 224t?
All of the twisted-pair ports are wired as MDI-X. Therefore, to connect end nodes, servers, or other MDI-type devices to these ports, use "straight-through" twisted-pair cable; but, to connect to hubs, switches, or other MDI-X type devices to these ports, use "crossover" twisted-pair cable.
For connections to the 10 Mbps ports, you can use Category 3, 4 or 5 unshielded twisted-pair cable, as supported by the IEEE 802.3 Type 10Base-T standard.
For connections to the 100 Mbps ports, use Category 5 only, as supported by the IEEE 802.3u Type 100Base-TX standard. Only twisted-pair cables with solid conductors are supported to the full 100 meters, do not use braided or drop cables.
Twisted-Pair Cable for Switch (MDI-X) to Computer (MDI) Network Connection
All twisted-pair wires must be twisted through the entire length of the cable. The wiring sequence must conform to AT&T 258A (not USOC). To connect PCs or other MDI network devices to these ports, use a "straight-through" cable as shown here:
Twisted-Pair Cable for Switch (MDI-X) to Hub or Switch (MDI-X) Network Connection.
Twisted-Pair "Crossover" Cable for Switch-to-Switch (or Hub-to-Hub) Network Connections
To connect hubs or switches or other MDI-X network devices to these ports, use
a "crossover" cable.
Fiber-optic cables connected to a HP fiber-optic transceiver installed in the switch's transceiver slot must be 1300nm wavelength, multimode cable conforming to the ISO/IEC 793-2 type B1, and ITU-T G.651 standards. To connect to the HP 100Base-FX Fiber Optic Transceiver Module, the cables must have SC-type connectors.
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Q: What are the features of J3175/77A switches?
The J3175A Switch 208t has eight 10Base-T ports and two 100-Mbps ports whereas the J3177A Switch 224t has 24 10Base-T ports. Of the two 100-Mbps ports, one is a fixed 100Base-TX port and one port is a media, flexible 100Base-FX port.
The expansion slot on the back of both switches accepts an HP J3178A Management Module or HP J3138A Internet Router Module. Both switches support Store & Forward, 1-Gbps PCI switch bus and Per-Port Memory switching technology. For full duplex on any of the fixed ports (10 or 100) you need the HP Management Module.
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Q: If the MAC address table overflows by receiving more addresses than the switch address table can hold, how will the switch treat incoming packets whose addresses are not in table (addresses which have not been learned)?
The switch floods (broadcasts) the packet to all ports, the same as a bridge would do.
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Q: Is the management module required to do full duplex?
Yes. There is no console on an unmanaged Switch 208t/224t, so there is no way to change the default configuration without the management module. The default configuration is that all ports are in half-duplex mode including the 100TX ports.
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Q: Is the management module required to use the Internet Router?
No. The internet router module does not require the SNMP management module to function in the Switch 208t/224t. It runs completely independently and has its own console, SNMP agent and management. It only gets power (and access to the network through port 1) internally from the Switch.
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Q: How does the Switch 208t/224t do stacking?
Switch 208t/224t do stacking through normal network connections using the network ports (100TX or 10Base-T). There is no separate or proprietary connector for stacking like the Advancestack Hubs.
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Q: Is the management module necessary to do stacking?
Since stacking is achieved by using normal networking ports (100TX or 10BaseT), no management module is required to stack or interconnect these switches. There is no port trunking feature on the Switch 208t/224t so the maximum bandwidth allowed between two unmanaged switches is 100 Mb/s. If the Management Module is used then the ports may be configured to Full Duplex, and then the bandwidth between the switches will be 200 Mbps.
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Q: How do I update the SNMP agent firmware on my Advancestack Switch 208t/224t?
The latest version of firmware may be obtained in any of the following ways:
-
HP FTP Library Service
ftp to ftp.hp.com
Login as anonymous
Password is your email address.
"cd" to the /pub/networking/software
Set the file type to binary by typing bin.
get "filename" to transfer the file to your local workstation.
-
World Wide Web
http://www.hp.com/rnd/software/switches.htm
Download the required file.
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Q: Can I connect a 10Mbps (10Base-T) cable to the Switch 208t/224t 100TX ports?
No, the 100TX ports, the fixed and the optional transceiver, are for 100TX only and will not support 10Base-T. If a 10Base-T port is connected to the 100TX port, the switch may attempt to auto-negotiate to 10 Mbps or 100 Mbps and end up in a nonfunctional state.
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Q: The 100TX connection on my Switch 208t/224t appears noisy.
The IEEE 802.3u standard specifies a maximum possible length of 100 meters of Category 5 cable for the 100TX connection. This is a point-to-point maximum length specified for a single cable. Your wiring plant (patch panel, connectors, wire-tied bundles, sharp right-angle corners) may contribute to attenuation, cross-talk and noise on Category 5 cable. You may need to reduce the overall length of the cable to compensate or use fiber-optic cables and the 100BaseFX Fiber-Optic Transceiver (HP J3193B). The maximum distance for fiber is 2000 meters.
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Q: Is there a T4 transceiver available for the Switch 208t/224t?
No, at this time there is no T4 transceiver available.
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Q: Does my Switch 208t/224t support full duplex?
The unmanaged Switch 208t and Switch 224t ports, 10Base-T and 100TX, operate in half duplex mode only. With the optional J3178A Switch Management Module installed, these ports can be configured to operate in full-duplex mode.
Access the switch console by using Telnet or attaching a terminal to the console connector. Follow the following path in the Console menus.
- From the Main menu, select Configuration.
- From the Configuration menu, select Ports.
- Select "Edit", use keyboard arrows to select the port,
and use the spacebar to select between half and full duplex.
The 100TX port can be configured to a fixed 100/Half, a fixed 100/Full, or Auto Duplex. The Auto Duplex allows for auto-detection between half and full duplex.
For more information
please refer to the HP
J3178A Management Module Installation and Reference Guide
(part number 5966-5228).
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Q: How do I connect a 208t/224t to a stack of 10Base-T hubs or Advancestack Switching Hubs?
The Switch 208t/224t can connect to a stack of 10Base-T hubs via the 10Base-T connectors and a crossover Category 3 cable as shown in the following illustration. Notice that the Switch 208t/224t provides a dedicated 10-Mbps connection to each 10Base-T hub. The 100TX high-speed ports are used to connect to local servers or the network backbone switch.
The Switch 208t/224t can stack your Advancestack 10Base-T Switching Hubs via a crossover Category 3 cable to either the 10Base-T hub port or the HP J3212A Advancestack 10BT Switch Module installed in the back of the Switching Hub.
The above illustration shows the connection via the 10Base-T ports on the Switching Hubs and the Switch 208t/224t. A crossover cable is needed for each segment of the hub. The number of crossover cables depend on how many segments were specified for your stack of Switching Hub; one to four crossover cables may be needed. This is shown in the following illustration:
The optional Switch Module can be installed in the Expansion Slot in any one of the Switching Hubs in a stack (an HP Management Module (HP J3210A) must also be installed somewhere in the stack for the Switch Module to work.) Below is an illustration showing the Switch Module installed in a Switching Hub.
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Q: When I connect a device (hub or client) to one of the ports on the Switch 208t or 224t, the LED of the port is only lit for 3 seconds, then goes off, and every 4 seconds it shows activity. Is this normal?
Yes, this LED behavior is normal. The default LED state is to show Link Detect for 3 seconds and then show Activity. In the Activity state, the LED will blink only when traffic is received. More traffic means more time the LED will remain on.
If the LED mode is changed to Link only, then when a cable is connected to a port, the LED will remain on. This cable would be a crossover cable connected to another NIC, hub, or switch. The LED behavior shows that a link signal is being received.
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Q: After rebooting or power cycling the Switch 208t/224t with the IOS Router module installed I see an Expansion Slot error message; what does this mean?
This is normal behaviour with the current firmware (all firmware up to version A.01.22). This message occurs because the Internet (IOS) router takes longer to come up than the current firmware expects. So one error message is issued as the switch and the router are coming up, then when the switch checks the router a second time, the Internet router is fully up and everything is fine.
Below is a sample error message:
W 12/31/90 16:00:01 system: Expansion Slot: failure, Failures: 1
Here is the message that is issued after the IOS Router has come up fully:
W 12/31/90 16:00:02 system: Expansion Slot: OK, Failures: 1
This is a typical boot up sequence in the event log:
CONSOLE - MANAGER MODE
I 12/31/90 16:00:00 system:------------------------------------
I 12/31/90 16:00:00 system: System went down without saving crash information
W 12/31/90 16:00:01 system: Expansion Slot: failure, Failures: 1
I 12/31/90 16:00:02 ip: entity enabled
I 12/31/90 16:00:02 ipx: entity enabled
I 12/31/90 16:00:02 tftp: entity enabled
I 12/31/90 16:00:02 bootp: entity enabled
I 12/31/90 16:00:02 timep: timep client enabled
I 12/31/90 16:00:02 tcp: configuration complete
I 12/31/90 16:00:02 tcp: entity enabled
I 12/31/90 16:00:02 telnet: Inbound telnet enabled
I 12/31/90 16:00:02 telnet: Outbound telnet enabled
W 12/31/90 16:00:02 system: Expansion Slot: OK, Failures: 1
I 12/31/90 16:00:03 ports: port 1 is now on-line
I 12/31/90 16:00:03 ports: port 17 is now on-line
I 12/31/90 16:00:03 ip: network enabled on 13.28.224.1
I 12/31/90 16:00:03 system: System Booted.
I 12/31/90 16:00:12 timep: client polling server at 13.28.230.4
I 12/31/90 16:00:12 timep: changing time
I 02/24/98 11:11:41 timep: new time set
I 02/24/98 11:11:45 ipx: Starting auto-discovery sequence
I 02/24/98 11:11:49 ipx: Discovered net bbb8022 (802.2)
I 02/24/98 11:11:49 ipx: network enabled on bbb8022:0060b06ecc05
W 02/24/98 11:12:22 console: lost DSR/DM signal
I 02/24/98 11:12:23 console: incoming call
I 02/24/98 11:12:33 console: connection established
I 02/24/98 11:12:35 mgr: SME CONSOLE Session - MANAGER Mode established
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Q: How
do I attach a LAN Analyzer to a Switch 208t/224t port to monitor
LAN traffic for diagnostic purposes?
You can designate a port for monitoring traffic on any one of the other ports on the switch. This is accomplished by copying all traffic from the specified port to the designated monitoring port. This feature is also referred to as "mirroring".
How to configure the Switch for Monitoring:
- From the Main Menu, select Configuration Menu.
- From the Configuration Menu, select Network Monitoring
Port.
- In the Actions menu, press "E" (for Edit).
- If monitoring is currently disabled (the default) then
enable it by pressing the spacebar (or "Y") to select "Yes".
- Press "Down Arrow" to move cursor to the Monitoring Port
prompt.
- Press the spacebar or type the port number to select the
port to use for the monitoring port. Attach the analyzer
to this port.
- Press "Down Arrow" to move to the "Monitored Port" field
and press the spacebar or type the port number to select
the port you want to monitor.
- Return to the Main Menu to select other function. You
don't need to reboot the switch; the Network Monitoring
port configuration is dynamically activated.
The port you select as the Monitoring Port is identified on the port status and counter screens and the port configuration screens with MP after the port number.
Note: The port you select as the Monitoring Port cannot participate in Spanning Tree protocol, so it will not be displayed on the Spanning Tree configuration or status screens.
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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:
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: 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: Why does my RS-232 console cable not work with certain HP Advancestack and switches?
There are many possible sources of console connection problems, including terminal emulator defects and incorrect configurations. Your HP Advancestack or ProCurve Networking by HP installation documentation discusses the correct configuration of the console port.
There is a known problem with a particular RS-232 cable that shipped with some of the following products:
- 178A HP Advancestack Switch 208/224 Management Module
- J3245A HP Advancestack Switch 800t
- J3100A HP Advancestack Switch 2000 (version A)
- J3100B HP Advancestack Switch 2000 (version B)
If the RS-232 cable with HP part number 5183-7247 is attached to the console port of certain HP Advancestack switch models before the switch is reset or powered up, the console will display:
Decompressing...done
then give no more output. You will not be able to access the switch's user interface through the console.
If the 5183-7247 RS-232 cable is attached to the switch's console port after the switch is already operational, you will not be able to see or access the switch's user interface.
The 5183-7247 cable cannot be made to work properly with the switches listed above at any baud rate or with any terminal emulator. The reason is that this cable does not transmit certain RS-232 signals required by those switches.
There is no problem with the RS-232 cable part number 5182-4794 that shipped earlier with the four Advancestack devices listed above.
If you have the cable 5183-7247 that you are trying to use with one of the HP Advancestack devices listed above, please contact your local HP Customer Care Center, which can arrange for a replacement cable to be sent to you at no charge as part of your product's warranty.
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