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Forum Discussion
high tcp segments resent
Hi.
When I try to stream any movie larger than 1gb from my readynas duo v2 it repeatedly freezes throughout the whole movie with a couple minutes in between freezes.
I have read lots of posts about this issue with all of them stating the same issue, but with no obvious answers.
I.e. http://www.readynas.com/forum/viewtopic.php?f=23&t=70869 (url is off in my BBcode)
Everyone always seem to be onto something, and some even get the problem fixed, but then without knowing how it was fixed.
And another thing is that they most often have these issues on an other type of readynas than I have.
I on the other hand have an obvious conclusion of what the problem is with my readynas duo v2
When I ssh into my nas and sniff my ip with the command: netstat -s [SNIP]
I get the following among lots of other info:
This is an unacceptably high number, it seems like I get a stack overflow, probably my router can't handle the large number of packets sent out through it. But only thing I hear people talk about is jumbo frames this jumbo frames that.
I have tried to ssh into /etc/default/services/ but it allows only admin access and I'm logged in as root.
So I can't even check if I can turn it on/off on my nas.
Isn't there anywhere you can set the tcp frame size?
Or what is the solution to make the segment resent count go down?
I really hope there's a straight answer to this problem, but it's probably as usual we will all just end up solving my problem without knowing what we did, or worse, not solving it at all.
I'm now putting out my hopes on you guys, the ones with wiz and awesomeness! ;)
When I try to stream any movie larger than 1gb from my readynas duo v2 it repeatedly freezes throughout the whole movie with a couple minutes in between freezes.
I have read lots of posts about this issue with all of them stating the same issue, but with no obvious answers.
I.e. http://www.readynas.com/forum/viewtopic.php?f=23&t=70869 (url is off in my BBcode)
Everyone always seem to be onto something, and some even get the problem fixed, but then without knowing how it was fixed.
And another thing is that they most often have these issues on an other type of readynas than I have.
I on the other hand have an obvious conclusion of what the problem is with my readynas duo v2
When I ssh into my nas and sniff my ip with the command: netstat -s [SNIP]
I get the following among lots of other info:
Tcp:
189 active connections openings
947 passive connection openings
0 failed connection attempts
89 connection resets received
2 connections established
500856 segments received
308970 segments send out.
11066 segments retransmited. <------------!!!!!!!!!!!! WT!
0 bad segments received.
99 resets sent
This is an unacceptably high number, it seems like I get a stack overflow, probably my router can't handle the large number of packets sent out through it. But only thing I hear people talk about is jumbo frames this jumbo frames that.
I have tried to ssh into /etc/default/services/ but it allows only admin access and I'm logged in as root.
So I can't even check if I can turn it on/off on my nas.
Isn't there anywhere you can set the tcp frame size?
Or what is the solution to make the segment resent count go down?
I really hope there's a straight answer to this problem, but it's probably as usual we will all just end up solving my problem without knowing what we did, or worse, not solving it at all.
I'm now putting out my hopes on you guys, the ones with wiz and awesomeness! ;)
3 Replies
- Segments get retransmitted because packets get lost. Queue overflow is one possibility, but there are others.
Note that the queues in the router are normally empty unless the router is downspeeding the connection.
Some causes of packet loss:
(a) bad cables. This includes cat-5 for gigabit ethernet (instead of cat 5e)
(b) failing switch ports (could be in the NAS, the far end device, or any intermediate router/switch
(c) WiFi interference (if the far end device is connected over WiFi
(d) gigabit->100 mbit ethernet downspeeding in the absence of ethernet flow control.
The TCP settings could potentially be adjusted in the far end PC, though I am not understanding why you think changing those settings would help. I think the cause is more likely physical layer, and that the solution probably lies there as well.
Can you tell us more about your home network setup? StephenB wrote: Segments get retransmitted because packets get lost. Queue overflow is one possibility, but there are others.
Note that the queues in the router are normally empty unless the router is downspeeding the connection.
Some causes of packet loss:
(a) bad cables. This includes cat-5 for gigabit ethernet (instead of cat 5e)
(b) failing switch ports (could be in the NAS, the far end device, or any intermediate router/switch
(c) WiFi interference (if the far end device is connected over WiFi
(d) gigabit->100 mbit ethernet downspeeding in the absence of ethernet flow control.
The TCP settings could potentially be adjusted in the far end PC, though I am not understanding why you think changing those settings would help. I think the cause is more likely physical layer, and that the solution probably lies there as well.
Can you tell us more about your home network setup?
Thank you for offering your knowledge :)
From my nas I have a 1m cat 5e cable going to a belkin N750 DB router, from that I have a 20m cat 5e cable going to a D-Link DGS-1005D gigabit switch, then a 1m cat 5e cable to my tizzbird F20 android media player.
I'll try moving everything except my dsl modem to where the media player is, and then just go with a 1m cat 5e directly between the nas, router and media player to sort things out.
Thank you for mentioning the cables ;)
To be continued...- Maybe also try connecting the NAS and the media player to the dlink switch.
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