How to extend the life of a networkbridge1 card - hardcode your PC/iMac with Jriver to 100Mbps/full duplex


#1

FYI, I wrestled with my iMac, Jriver and Directstream with the network bridge 1 for a while and I only realise now that the networkbridge1 auto-negotiates to 100 Full duplex ( I used a managed switch to check this). Meanwhile all my kit like the DSL router is 1 Gbps auto and my unmanaged switch is 1 Gbps auto too . From an electrical point of view we have the following differences:
100baseTx only two pairs are used of the ethercable and frequency is 80mHz
1000baseT uses the four pairs of the ethernet cable and the frequency is 100mHz
So, my iMac (1 Gbps auto) was pumping out packets faster than the network bridge1 could receive. Random stops I imagine translates to interface buffer overflows (with packets drops in interface queues) on the unmanaged switch resulting in too many out of sync packets on the network bridge1. So cheap remedial is to hardcode the network card on your iMAC to 100Mpbs and all your troubles are gone with the networkbridge1. Most network manufacturers group interfaces in a few ASIC’s and manage their hard set queues there, depending on the architecture of the switch. That’s why you could get better performance if you use port1 (ASIC1) for your PC and say port 12 (ASIC2) for your streamer. It’s better to match the clocking speed and not depend on buffer depths of those unmanaged switches. Now, there is more space and more detail in my soundstage and all is stable again. I am still looking for a networkbridge2 though at some point. In the mean time I am enjoying the music again. I am a network guy and my usual mantra at work is “it’s not the network”, but here it was. Hopefully the networkbridge2 auto-negotiates to 1 Gbps like most of the unmanaged switches, laptops and recent computers out there.


#2

Bridge II absolutely auto-negotiates data rate: 100mbps v 1gbps. I have all gig switches and every port indicates 1gbps except the Bridge II which indicates 100mbps.


#3

Here too. BridgeII doesn’t seem to support 1Gps.


#4

I can understand that the new bridge2 only auto-negotiates to 100Mbps since the buffers would need to be huge when on 1Gbps. And there would be no need since playback does not need to be instantaneous anyway (It’s not a phone call). I wonder if the higher-level protocols can throttle down the stream of data or if the direct stream just relies on whatever Jriver sends to it. Ah the world of TCP window sizes etc comes to mind but that would become very complex, a client on the Directstream and on the iMac to throttle the stream. 100 Mbps in, 100 Mbps out with the same clocking speed (100BaseTx) seems to me the best option (KIS, Keep It Simple).


#5

I have a Netgear GS108 unmanaged switch which has factory default some congestion avoidance mechanism for dissimilar network speed interfaces. The network scheduler does WRED, which is Weight random early detection for congestion avoidance. I would have lost a few random packets on the switch (UDP with no retransmit) and that would explain the loss of space and a slight harshness in the soundstage.
I wonder if I still need the network bridge2 soundwise since congestion does not come into play when both iMac and streamer with networkbridge1 are 100Mbps.
Are other changes made to the networkbridge2 which would influence the sound?
Do you notice a difference with the networkbridge2 when you set your iMac/PC with Jriver to 100Mbps?


#6

Last update: I have replaced the stock power adapter of the Netgear switch for a stabilised powers supply and my soundstage got bigger. Big drums have wet echo effect, which is dampened msecs later due to the recording room acoustics. I have a way better sound depth as well. I have moved the Netgear to my audiorack as well, now with a short cat6A cable to the streamer and a longer cat6A cable to the iMAC. Both 100 Mbps of the iMac and the streamer still on port 7 and 8 and my other interfaces 1Gbps interfaces to port 1 and 2. I will be enjoying the networkbridge1 for another while. The illusion machine just became very palpable.