MTU

Hi, just thought I would share this, if your a talktalk customer and using the supplied router the default MTU is 1500, I purchased a Netgear D7000 the default on the router is 1500, I was reading the talktalk help pages and noticed that if using your own router to try MTU 1432 download went from 58 to 68.

Kev

TalkTalk routers are supplied at MTU 1432 for ADSL. The network fully supports MTU 1492 though, and that is the optimum. Any MTU value above 1492 should be avoided due to packet fragmentation (TalkTalk routers will not allow any value above 1492).

Hi Oliver341

Now not so sure it was the MTU as reset MTU back to 1500 and no difference, may have been the new router increased the speed at the same time I was toying with the MTU.

Do you think it may have nudged something to get that speed increase ?

Kev

Not sure. If your router is currently set to MTU 1500, can you paste the results of this:

ping -f -l 1472 bbc.co.uk

Hi Oliver341

Appears to be a Netgear thing , thank you for the help.

Pinging bbc.co.uk [212.58.244.22] with 1472 bytes of data:
Reply from 192.168.0.1: Packet needs to be fragmented but DF set.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 212.58.244.22:
Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),

No problem. As expected, MTU 1492 is the optimum value.

The optimum & max. MTU for Fibre (from your speeds) is 1492. 1500 is only for ADSL over PPPoA.

Thank You

In reply to a post by XRaySpeX:

The optimum & max. MTU for Fibre (from your speeds) is 1492. 1500 is only for ADSL over PPPoA.

The MTU on TalkTalk PPPoA (ADSL) can only go up to 1492 before fragmentation occurs, so it's slightly different to PPPoA on ADSL over Sky and BT which can achieve 1500.

PPPoE on fibre as you say is 1492 max on any provider, but since Sky use DHCP on fibre they can use MTU 1500.

Edited by Oliver341 (Mon 08-Feb-16 23:40:11)

In reply to a post by Oliver341:

PPPoE on fibre as you say is 1492 max on any provider, but since Sky use DHCP on fibre they can use MTU 1500.

Not true. With hardware and software that supports RFC 4638, MTU 1500 is possible over PPPoE. This post comes to you over a connection to Zen with MTU 1500 (HG612, pfSense 2.3.2 running on a box with a jumbo capable Ethernet interface used for the link to the HG612, MTU 1500 configured on the pfSense WAN interface).