Geekzone: technology news, blogs, forums
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.


1200 posts

Uber Geek


#11713 7-Feb-2007 19:22
Send private message

Hello Everyone,

I have a client which is having issues very symptoms very similar to MTU packet size issues (unreliable browsing, Terminal Server sessions failing etc)

This client has a laptop and a 3G card, and sits out on a boat way past great barrier island. They can only get GPRS service, but has been working fine for the last year or so.

I setup my laptop to replicate their settings (Clean install of Windows XP) VMC 7.03.0004 (latest) and a 3G Card locked to GPRS with APN of and internet.

Unusual results. I can ping usually with up to a 1500 MTU from a broadband connection (Clear's DNS servers.)

From the GPRS connection I can only send a ping -f -l 64 and get a reply.

If I send a do not fragment and packet size of 65 and above it does not get a reply - BUT ALSO does not recieve a packet needs to be fragmented.

The maxmum packet I can sent with a fragmentation error is 1476, which seems right from what google says (but most dialup connections are 576 MTU)

My gateway when on Vodafone is I can send packets of up to 1476, but they get eaten after this. Seems to be a GPRS problem, and perhaps even only on this gateway.

I called Vodafone Data support, but the only guy which knew had gone home for the day.

Questions - Whats the MTU meant to be for Vodafone GPRS??? Surely it isn't 64!!!

Tyler - Parnell Geek - iPhone 3G - Lenovo X301 - Kaseya - Great Western Steak House, these are some of my favourite things.

Create new topic

1200 posts

Uber Geek


  #60040 7-Feb-2007 19:48
Send private message

I dug a little deeper, I did a tracert and then pinged each host, some didn't respond, and the ones that did allowed 1765 sized packets all the way to what looks like the internet gateway then simply dropped them, unless they were 64 bytes or under!

  1   577 ms   695 ms   683 ms [myself]
  2   650 ms   581 ms   580 ms
  3   681 ms   576 ms   581 ms
  4   694 ms   599 ms   599 ms [not pingable]
  5   501 ms   581 ms   737 ms [not pingable]
  6   761 ms   719 ms   839 ms [not pingable]
  7   594 ms   599 ms   737 ms
  8   772 ms   737 ms   719 ms

Tyler - Parnell Geek - iPhone 3G - Lenovo X301 - Kaseya - Great Western Steak House, these are some of my favourite things.

Create new topic

News »

Vodafone enables 5G roaming - for when international travel comes
Posted 30-Oct-2020 15:03

Spark awards funding to Kiwi businesses in 5G funding initiative
Posted 30-Oct-2020 14:58

Huawei launches IdeaHub Pro in New Zealand
Posted 27-Oct-2020 16:41

Southland-based IT specialist providing virtual services worldwide
Posted 27-Oct-2020 15:55

NASA discovers water on sunlit surface of Moon
Posted 27-Oct-2020 08:30

Huawei introduces new features to Petal Search, Maps and Docs
Posted 26-Oct-2020 18:05

Nokia selected by NASA to build first ever cellular network on the Moon
Posted 21-Oct-2020 08:34

Nanoleaf enhances lighting line with launch of Triangles and Mini Triangles
Posted 17-Oct-2020 20:18

Synology unveils DS16211+
Posted 17-Oct-2020 20:12

Ingram Micro introduces FootfallCam to New Zealand channel
Posted 17-Oct-2020 20:06

Dropbox adopts Virtual First working policy
Posted 17-Oct-2020 19:47

OPPO announces Reno4 Series 5G line-up in NZ
Posted 16-Oct-2020 08:52

Microsoft Highway to a Hundred expands to Asia Pacific
Posted 14-Oct-2020 09:34

Spark turns on 5G in Auckland
Posted 14-Oct-2020 09:29

AMD Launches AMD Ryzen 5000 Series Desktop Processors
Posted 9-Oct-2020 10:13

Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.

Support Geekzone »

Our community of supporters help make Geekzone possible. Click the button below to join them.

Support Geezone on PressPatron

Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.