Some MVP Load Problems due to port not going to half duplex

[lseats]

Sub has the code for connecting with the MVP working great in the latest release, but I started having problems again where the dongle.bin file would never finish loading. I believe I understand why that is and how to fix it.

I believe that what is happening is that since the MVP switches to half duplex at the end of the dongle.bin load, if the switch port does not also switch it will not allow the load to finish. My switches had been doing that most of the time, but for some reason they got in a mode that would not allow them to switch.

What I did as a temporary fix was use one of Tipster's tricks and shut down all of my network equipment and bring it all back up one piece at a time. That reset my switches so that they could switch to half duplex when the MVP does.

Does anyone know of an inexpensive switch that will allow you to lock ports to half duplex? I think that would be a permanent fix and greatly enhance the WAF for many of us.

[csy]

since the MVP switches to half duplex at the end of the dongle.bin load.

I don't use a MVP and know little about them, however I do know a lot about Ethernet. It does sound like an auto-negotiation issue on the surface of it all. However you implied the Ethernet starts off as full-duplex, therefore you should be trying to keep it as full-duplex.

Half-duplex induces packet jitter which is potentialy damaging to streaming content, and therefore not recommended.

I don't know how the dongle.bin works, but if it is forcing your PC Ethernet port into a particular speed/duplex, this will disable auto-negotiation advertisements over the wire, and the directly connected remote device (switch?) will not receive the link partner capabilities advertisement and fall-back to half-duplex mode (assuming the remote device is auto-negotiating).

My advice is to either diagnose why you are loosing full-duplex and fix it so you are retaining full-duplex. You can buy a 'managed' switch and force speed/duplex on the ports but you are likely to create more duplex mismatch issues by doing so.

[lseats]

I don't use a MVP and know little about them, however I do know a lot about Ethernet. It does sound like an auto-negotiation issue on the surface of it all. However you implied the Ethernet starts off as full-duplex, therefore you should be trying to keep it as full-duplex.

Half-duplex induces packet jitter which is potentialy damaging to streaming content, and therefore not recommended.

I don't know how the dongle.bin works, but if it is forcing your PC Ethernet port into a particular speed/duplex, this will disable auto-negotiation advertisements over the wire, and the directly connected remote device (switch?) will not receive the link partner capabilities advertisement and fall-back to half-duplex mode (assuming the remote device is auto-negotiating).

My advice is to either diagnose why you are loosing full-duplex and fix it so you are retaining full-duplex. You can buy a 'managed' switch and force speed/duplex on the ports but you are likely to create more duplex mismatch issues by doing so.

You would be correct, except that the MVP only has an 8k buffer and can not handle full duplex for streaming. If you get it to load at full duplex then there will be many dropped frames due to buffer overflows. The MVP forces it's connection to half duplex to deal with that problem and if the switch does not cooperate it either won't finish the load, or it will dissconnect shortly after it starts playing a file due collisions, or it will play but with many dropped frames.

[lseats]

I see you're using Server 2003, did you know you could use Server 2003 as Router since all the server software you need for this project is included. I would and you can take control of how the LAN is receiving packets. You could use 10/100/1000 depending on what type of NIC you have installed. So far this is working better than using one of those store bought Routers.

You need an old PC to make into a Router and install Server 2003. Also two NIC cards.

My network is too decentralized to make much use of that plus I don't want to buy another server 2003 license just to make it into a router. What I need is control at the edge of my network so I can set just the ports that my MVPs connect to at half duplex.

[csy]

You would be correct, except that the MVP only has an 8k buffer and can not handle full duplex for streaming. If you get it to load at full duplex then there will be many dropped frames due to buffer overflows. The MVP forces it's connection to half duplex to deal with that problem and if the switch does not cooperate it either won't finish the load, or it will dissconnect shortly after it starts playing a file due collisions, or it will play but with many dropped frames.

If this truly how Hauppauge implement flow-control, then it reflects very poorly on Hauppauge. This method you describe is very crude and regulation will vary with the Ethernet utilisation, not to mention the jitter it is introducing. The streaming transmitter software should regulate the transmission rate.

[lseats]

If this truly how Hauppauge implement flow-control, then it reflects very poorly on Hauppauge. This method you describe is very crude and regulation will vary with the Ethernet utilisation, not to mention the jitter it is introducing. The streaming transmitter software should regulate the transmission rate.

That is the way it works. It may not be good networking, but as long as the port it is plugged into is at half duplex it streams beautifully. I record at a pretty high quality and you can't tell the stream on the MVP from a direct signal on the TV. When I run Netpersec it shows the stream to average 8 megabit/sec with the settings I use.

[lseats]

I don't know about going half rather than full, I've never gone that way in a network to much problems. If you need help, help is here. I don't know what's going on at your end. What you have for a switch or router there? Check you event viewer and see if you see anything in the system for TCPIP or DHCP errors? You shouldn't have to change port speed for the MVP.

I don't really need any help, I'm just looking for suggestions on a low cost swtich that lets me set the port parameters.

I've done enough experimenting with the MVP and network settings and read enough about what others have done to know exactly what is happening. As long as the switch cooperates and switches to half duplex when the MVP does there is no problem. All I want to do is force the port attached to the MVP is on to half duplex so I don't have to rely on the auto-sensing to work. From experience I know that auto-sensing is not always reliable.

If you want to see what is happening when the MVP connects hook it to a switch that has an indicator for full/half duplex and watch it as it boots up. It will start at full duplex and load the dongle.bin. It will then switch to half duplex and start the software. You will see the port on the switch indicate half duplex about the time the program starts. If the switch is a little slow to switch to half duplex you will see the screen flash just before GBPVR starts running.

If you want to read more about this read this thread from SHSPVR. The last post on the second page describes what the MVP does:

http://www.shspvr.com/smf/index.php?topic=3602.0

[csy]

I think i know what is going on here and it has nothing to do with buffer overflows on full-duplex.

Based on the linked forum thread you gave.

When the MVP is powered-on, it will auto-negotiate with the link partner (eg Ethernet switch) and if the partner is a standard 10/100 auto-negotiating port, then both will negotiate to 100/full.

When MVP playback starts, the MVP does a 'reset' on its Ethernet port, causing the port to re-auto-negotiate with the link partner, however the link partner did not see 'link' fail, therefore does not send any advertisements to to the MVP, nor does it re-negotiate its speed/duplex. Because the MVP does not see any advertisements it falls-back to half-duplex. Under these circumstances the MVP port can self-detect speed, so it ends up configuring its port to 100/half if the link partner is a 10/100 device. So what you end up with is a duplex mismatch because the MVP is half-duplex and the link partner is still using its original negotiated full-duplex.

Duplex mismatches causes packet loss. With the MVP in half-duplex but the link partner in full duplex, the MVP Ethernet port will drop received frames (packets) if it is also transmitting a frame at the same time. This will be seen as video studdering.

Some Ethernet switches and NIC's respond to 'link-down' quicker than others, which is why some switches/NIC's have no problems with the MVP but others do.

So the problem is a MVP bug causing the MVP Ethernet port to reset (or initialise) prior to playback. This needs to be represented back to Hauppauge as a fault so they can fix it!

A workaround would be to force the link partner port to 100/half, but this will cause packet jitter due to re-transmission delay when collisions occur, and possible packet loss due to buffer-overflows on the link partner port. If you were to implement this workaround, it only needs to be applied on the link partner port (switch port) facing the MVP, and not the port facing the HTPC, or the HTPC port itself (unless the MVP is directly connected to the HTPC).

Edit:
My recommendation would be to get people to post the make/model of unmanaged (cheap non-configurable) switches that the MVP is known to stay at 100/full and buy one of those switches (it would be usefull if you bought a switch with speed/duplex indicators). Alternatively, each time the MVP falls-back to half-duplex (if this happens infrequently?), you could manually unplug/replug the MVP Ethernet cable to force both the MVP and switch to re-negotiate together.

[onestar]

Yeah Tipstir, I find that the problems I was having with MVPs were all fixed, when I started to run my own tftp/dhcp server for them, never had any issues with the routers/mvps.

I have one in a plain netgear hub,
one into a belkin accesspoint->into a netgear switch -> netgear hub,
another into another netgear switch->netgear switch -> netgear hub.

However even with all that, running a DHCP server (saying download dongle.bin) and a TFTP server (supplying the file), all MVPs load fine, no matter how often I try power off and on. Without the specific DHCP/TFTP setup, powering up was often hit and miss.