12 public posts in this discussion.
I have had some issues with Packet loss so have learnt this.
You standard (512 - 128) Max Packet send is 1492
So Do this cmd
ping -l 1492 -f www.google.com
This then tells if you are getting fagmented files.
If you are decrease by 10 per test 1482 - 1472 - 1462
Then this will give you Maxium Packet size you should be sending.
If you do this test please note Maxium size and Provider Below
uh, it won't give you your mtu
you need to add 28 to it, to account for packet headers (icmp + ip)
and i posted that about half an hour ago in a different thread :P
C:\Documents and Settings\GusIsInsane>ping -l 1472 -f www.google.com
Pinging www.google.akadns.net [216.239.39.99] with 1472 bytes of data:
Reply from 216.239.39.99: bytes=1472 time=526ms TTL=42
Reply from 216.239.39.99: bytes=1472 time=522ms TTL=42
Reply from 216.239.39.99: bytes=1472 time=525ms TTL=42
Reply from 216.239.39.99: bytes=1472 time=524ms TTL=42
Ping statistics for 216.239.39.99:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 522ms, Maximum = 526ms, Average = 524ms
C:\Documents and Settings\GusIsInsane>
ignore the time.. because i'm still getting a ping average of 100.. :(
C:\Documents and Settings\Stephen Caraher>ping -l 1472 -f www.google.com
Pinging www.google.akadns.net [216.239.53.99] with 1472 bytes of data:
Request timed out.
Reply from 216.239.53.99: bytes=56 (sent 1472) time=402ms TTL=236
Reply from 216.239.53.99: bytes=56 (sent 1472) time=402ms TTL=236
Reply from 216.239.53.99: bytes=56 (sent 1472) time=403ms TTL=236
Ping statistics for 216.239.53.99:
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Approximate round trip times in milli-seconds:
Minimum = 402ms, Maximum = 403ms, Average = 402ms
C:\Documents and Settings\Stephen Caraher>
So for me I should change my MTU to 1500 and my packet loss will be gone?
Following Pladines statment , you would take 28 from it and make that your MRU.
And you lost a packet at 1472
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Christ, you lot, you can't base your average packet loss off of a sample of 4 packets going to a vastly remote site!
Pick somewhere closer, ping that, and use the -t option so you ping a whole bunch of times.
And if you're really stressing about your latency, drop your MTU to 470. That means you should suffer from zero fragmentation across all possible paths.
But frankly, you can cause more harm than good buggering about with your MTU and MRU without knowing what you're doing.
Oh, and you can get away with a bigger MRU than you can an MTU since you download faster than you upload.
incidentally, my MTU is 1464, but remember I'm on wireless
Dark, I was following insurctions from my ISP. (WHo don't know as much as pladin it would apppear)
When you lower your MTU are your decreasing Maxium possible bandwidth.
So then What would be the correct MTU for 128 kps? And MRU for 512 kps?
Isn't this the real question?
1492 should get you by on a dsl connection, as mentioned in another thread.
no real need to mess with your mru at all.
having a very low MTU is bad, because it means you send a lot more packets. more packets = more protocol headers. more headers = higher percentage of overhead.
i am firmly of the opinion that if your setup works, don't change anything.
And I fully stand with Paladin on that. If it works, leave it the hell alone.
While reducing your MTU does mean you get more protocol headers, thus more overhead, it also means that should those packet have errors, those errors are detected faster, and thus can be replaced faster.
On a noisy connection, this helps a bit. It also causes your latency to drop, but reduces your throughput a bit.
Oh, and your ISP is a bit daft if they're telling you to check YOUR packet loss using a 4 packet sample going to a site that goes through routers they have no control over :)
Well if your On Bigpond expect daftness because technical support don't really know crap... If they don't know the answer, their response is "Update Windows" or "Reformat" :?