Hi Folks, I'd welcome comment on the following situation, which has arisen since I've (temporarily) changed my home network topology.
Previously (machines designated as A, B, C):
ADSL---Modem | Hub_1----------------A [at which I sit] | 5 metres | 10 metres| | | 1 metre Hub_2----------B | +------------C 1 metre
The above has worked very smoothly.
Now, in order to have machine to hand while investigating a hardware (power switch) issue, I have brought it near to machine A, with the resulting topology:
ADSL---Modem | Hub_1----------------A [at which I sit] | | 5 metres | +-----------------C | 10 metres| | | | 1 metre Hub_2----------B
Now, when I am sitting at A and running certain X apps on C (which have relatively heavy throughput such as raster re-drawing of sections of screen), there is clearly congestion: output from C on A's screen can hangs for a few seconds at quite frequent intervals. But it can also happen from time to time when I'm simmply typing text into C (as now).
Not much has changed: the cable to C has been plugged into a different hub, with a different cable (5m instead of 1m).
Comments would be welcome! I don't think such a change should have much effect.
Best wishes to all, Ted.
-------------------------------------------------------------------- E-Mail: (Ted Harding) ted.harding@nessie.mcc.ac.uk Fax-to-email: +44 (0)870 094 0861 Date: 16-May-07 Time: 23:14:22 ------------------------------ XFMail ------------------------------
On Wed, May 16, 2007 at 11:14:25PM +0100, Ted Harding wrote:
Not much has changed: the cable to C has been plugged into a different hub, with a different cable (5m instead of 1m).
Do you really mean hubs? or are they switches? and are they all 100 meg hubs or 10 meg hubs? and are they all indicating that everything is plugged in at 100 meg?
Adam
On 16-May-07 22:28:13, Adam Bower wrote:
On Wed, May 16, 2007 at 11:14:25PM +0100, Ted Harding wrote:
Not much has changed: the cable to C has been plugged into a different hub, with a different cable (5m instead of 1m).
Do you really mean hubs? or are they switches?
Now that you ask -- they are described as switches. Sorry to have been sloppy about this.
and are they all 100 meg hubs or 10 meg hubs?
This may be the crucial hint. In the diagram of the current topology:
ADSL---Modem | Hub_1----------------A [at which I sit] | | 5 metres | +-----------------C | 10 metres| | | | 1 metre Hub_2----------B
(still calls them "Hubs", but never mind), "Hub_2" is a 5-port which (IIRC) claims that each port can independently negotiate its rate with whetever its connected to. There is no such claim for "Hub_1". Now: Machines A and B have 100BaseT capable cards, while C (the one I moved from "Hub_2" to "Hub_1") only has a 10BaseT (the basic reason for this is that the Linux on C is so old that its drivers do not support more recent cards, not even 3C589, and it's using an 8390 driver).
So a possible explanation is that A is working at 100mps, and C is working at 10mbs, and both are plugged in to a switch whose separate ports are not independently adaptable; whereas previously B and C were plugged in to a switch where one port could handle the 100mbs and the other could handle the 10mbs.
and are they all indicating that everything is plugged in at 100 meg?
I don't know -- how can one tell?
Thanks for the response! Ted.
-------------------------------------------------------------------- E-Mail: (Ted Harding) Ted.Harding@manchester.ac.uk Fax-to-email: +44 (0)870 094 0861 Date: 17-May-07 Time: 07:56:16 ------------------------------ XFMail ------------------------------
On Thu, May 17, 2007 at 07:56:43AM +0100, Ted Harding wrote:
Now that you ask -- they are described as switches. Sorry to have been sloppy about this.
That's ok, it's an important detail I didn't want to assume you meant switch when you did really have hubs.
So a possible explanation is that A is working at 100mps, and C is working at 10mbs, and both are plugged in to a switch whose separate ports are not independently adaptable; whereas previously B and C were plugged in to a switch where one port could handle the 100mbs and the other could handle the 10mbs.
More or less what I'm thinking, it might be autonegotiation failing but you can get the status of ethernet connections with the program mii-tool and force them to the right values if necessary. Just make sure you look at the device stats from ifconfig for things like collisions and errors etc. it might be that this will reveal what is happening.
and are they all indicating that everything is plugged in at 100 meg?
I don't know -- how can one tell?
mii-tool or look at the blikenlights, there will be (on most, not all) switches be a light to indicate if a port is set to 100 meg or not.
Adam
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Adam Bower -
ted.harding＠nessie.mcc.ac.uk