HP Advancestack Hub J2419A

Is anyone familiar with the HP Advancestack Hub J2410A? I recently acquired this unit and am having some difficulty getting it up and running.

I checked the Hewlett Packerd website, and was unable to locate an owners manual, or any other information on how to set this unit up.

Any help would be greatly appreciated.

 

http://www.hp.com/rnd/support/faqs/100vg_hub.htm

I guess the main question is, do you want to use old technology like this on your network?

This was an excellent high-end device in it's day but it remains a 10Mbps hub so unless the rest of your network is equally old, you might not want the device on your wire.

A low-end (and fairly low-cost) switch will have much better performance.

Telnet (so remote) management modules in some of these devices were nice and a managed switch won't be so low-cost but ....

 

On anything larger than 10 or so users, a managed switch can be a very worthwhile investment. If you're replacing a managed hub stack, I'd definitely recommend going for a managed switch. The traffic information and fault diagnosis you get with a managed switch is well worth the relatively small additional cost. HP Procurve range are a personal favourite, but any of the major makes are good: Cisco and 3Com for example.

 

Thanks, guys, for the responses, and thanks for the link, Newt, that gave me the info I needed.

Seems I need an "SNMP/Bridge Module" to make this thing work. As I didn't pay anything for this, I'd be better off spending my money on a faster switch/hub. Saw a nice one on Newegg.

The company I work for is upgrading their entire computer system, and they know I'm the only guy in the plant who likes to mess with computers, so they gave me an AdvanceStack J2601A 24 Port Hub, an AdvanceStack J2601B 24 Port Hub, and the above mentioned J2410A 15 Port Hub.

I was kinda hoping to save some bucks and use the 15 port unit. Oh well.

 

A quick-and-dirty on hub vs. switch in case you need to justify cost and not using the hubs. This holds true for pretty much any hub since they were just starting to get into higher-speed ones when switches came down in price and made the whole thing not worth doing. I'll limit this to 100Mbps networks since Gigabit is probably serious overkill for most smaller networks and lots higher cost.

- Hub max speed 10Mbps and usually half-duplex (send or receive but not both at once).
- Switch normal speed 100Mbps full-duplex.
*** so already a switch is 15-20 times faster than a hub

- Hub divides bandwidth (the 10Mbps) among all the ports so in theory a 10 port hub fully loaded with all PCs moving data as fast as they can could offer 1Mbps to each port.
- Switch gives full bandwidth (100Mbps if the PC can handle it) to all connectec devices.
*** so the switch is now possibly 100-150 times faster than the hub

- Hub 'knows' nothing about other devices on the network and when PC-A wants to connect to PC-B, the hub uses a broadcast that all PCs on the network receive while PC-A & PC-B agree on how to talk.
- Switch 'knows' quite a bit about other network members and can usually connect PC-A to PC-B directly.
*** so less junk traffic on the network

Note that a switch has no problem if the NIC in the PC can only run at 10Mbps and if you have some of them (older ones) you can set them to 10Mbps full duplex and get double the performance they could manage on a hub.

 

Newt,

Hope you don't mind me adding some corrections. I agree with your overall statements - switches are in almost all circumstances better than hubs.

One advantage I would add is error handling. The only errors hubs can deal with are voltage/current problems and possibly clock problems. A switch reads in each Ethernet Packet and can discard any erroneous packets (thereby stopping them spreading around the network). Packets that are too short or too long, have CRC checksum errors, errors in the Ethernet header can all be dealt with at the switch. The best switches will even change the way they behave depending on the number of errors they are receiving.

Therefore, if you have a PC sending out faulty packets, in a hub network those packets go to all the computers on the network and they all have to deal with the errors. In a switched nework they get blocked at the switch, so only the PC with the fault gets slowed.

There were plenty of 100Mb/s Hubs about before the prices of switches started falling dramtically. So a switch is potentially twice as fast as hub (because you can communicate in both directions at the same time)

A hub know nothing about the network. All it does is relay electrical signals from one port to all the other ports. A hub doesn't just broadcast while the PCs negotiate. It will broadcast all the time. Perhaps an example will help make the point.

1. PC A wants to send a packet to PC B. To do so it must first find out what PC B's address is. It does this by sending an ARP request out as a broadcast (I'll ignore ARP Cache).

As it is a broadcast, a switch treats the out going ARP request the same way as a hub and send it out on all ports. However, it does do something the hub won't. It will look at the source MAC address on the ARP broadcast, that is the address of the PC where the packet came from. It now knows which port PC A is connected to.

So at this point both a hub and switch would act the same way. If anything the switch would be a little slower, while it reads in the packet before sending it out.

2. All the computers in the local subnet would receive the ARP broadcast. Most will discard it. However, PC B will recognise it as another PC wanting to know its address. PC B will send an ARP response back to PC A. However, as the packet from PC A included PC A's MAC address, PC B doesn't have to use a broadcast. It can send the packet directly to PC A.

As the ARP response is sent back to PC A, on a hub network all the hub sees is another set of electrical signals to repeat on all other ports. So even though the packet is sent to a particular MAC address, the hub still broadcasts it to every PC. And every PC's network card has to deal with discarding the packet, except PC A which will accept it.

On the switched network however, the switch will receive the ARP response, read the destination MAC address. It knows from step one the port PC A is on, and therefore knows it can send the packet out on this port and it will get to the right destination. The packet goes out on one port and only one port.

3. PC A and PC B now know each other's MAC addresses. They no longer need to broadcast. So they continue their communication directly.

However, the hub is stupid. Every packet gets broadcasted to every port through out the whole transmission. And because all the ports are being used, all the other PC have to wait, while a packet goes between PC A and PC B, until they can send packets. And they all have to discard all the packets that get to them, but weren't addressed to them.

With the switch, it is able to restrict the comunication solely to the two ports to which PC A and PC B are connected. At the same time it can also allow other PCs to communicate.

THe down side of this is that it becomes much more difficult to monitor network traffic as only the two PCs communicating see their traffic (in a single switch environment). This is what makes trouble shooting a switched network so much more difficult than a hub network. However, managed switches have the tools to give you the information you need to trouble shoot problems. That is why I would always recommend managed switches on all but the smallest networks.

In almost all circumstances a managed switch is best!

 

Thanks for the corrections and I certainly don't mind those when I goof.

Wasn't aware that 100Mbps hubs ever really got off the ground.

And double thanks for the other clarifications.

 

Not a goof! Most people don't know how the underlying kit works. I was lucky - had an employer who sent me on some excellent courses.

I did most of my network training about 4 years ago - Intel and Cisco Networking courses. At that time 24 port 10/100 hubs were still being shipped and were cheaper than the equivalent switches. In fact, Intel were boasting about their 330T hub having per port 10 or 100 speed switching (many hubs were either switchable to only 10 or only 100, and others acted effectively as two hubs, one running at 10, and one at 100, with a optional bridge between the two rails).

If memory serves me right at the time you could buy a stackable 24 port hub for about 500 pounds (UK), the cheapest standalone 24 port unmanaged switches were about 700 to 800 pounds. Stackable managed switches were around a thousand pounds. Of course if you went Cisco you'd have to pay an arm and a leg more and get a slower switch

A lot has changed now. We've just bought a managed 24 HP switch for about 250 pounds. You'd find it hard now to find a decent 24 port hub.