Broadband Tech > Networking > correlation between the WAN MTU and security for the LAN.

reply to neftv

Re: correlation between the WAN MTU and security for the LAN.

I did my own experiment just to try something out. I know this has nothing to do with P of D or DDos attacks but still...
I have two IPTV boxes and one Windows 7 ITX mini computer and I frequently set them to watch streaming live TV feeds at the same time. ( I have an in house cable feed where I put each device on a channel number) With the MTU set at 1500 these feeds frequently stop on me for no apparently reason and not all at the same time (Mostly each at different times). When I have my Shibby firmware enabled RT-N12 router set for say 1420 MTU these feeds just keep working and working. If any of the feeds stop it will be because the streaming server needs to be reset.

MTU on cable is 1500—MTU on DSL tends to be less than 1500 so, if you have DSL, this might be why a smaller MTU resolves your issues. That said, PMTU should figure out the best MTU for a connection, but many devices/routers/firewalls break this/are misconfigured and break this.

So to answer you I am on Verizon Fios. I thought Fios was 1500 MTU but I guess not for watching streaming media for the long duration. I know that when I set my MTU to default (1500 greyed out) in the Shibby enabled RT-n12 b1 router I get my live TV streaming interrupted routinely. When I set to manual and something lower than 1500 well I only tried 1425 1420 the streams just keep playing on my 3 devices.

Well, I don’t have Verizon FiOS, but a search quickly turned up »www2.verizon.net/help/fios_setti···more.asp, which says the optimal MTU for Verizon FiOS is 1492.

That makes sense now as that part of the site looks fairly new. Thanks.

reply to Bink

I have always been on DHCP with Fios. I just can't use 1500 if I want to be able to receive streaming media for any length of time.
1492 seems to be holding good for me.