Can I use a a SonicWALL TZ270 instead of Home Hub3000 / MTU Question

[tyler3]

Does anyone with a business have a homehub3000 and swap it with their own equipment instead? Also, have you been able to find out what your MTU is on your modem?  I'm speaking about the wireless home 50 package.

We have a sonicwall TZ270 we'd like to use instead because we are setup with a vpn tunnel back to the USA to our other office.  We have IPSec overhead we have to account for in our MTU setting on our WAN interface, so I need to just use this appliance or find out how to mimic the MTU on the modem so they are the same value (which you cant do from what tech support tells me)

Looking for what others have done in similar positions. Thank you

[Vanadiel · Accepted solution]

I directly use the GPON, MTU is 1492 for PPPOE connection.

[tyler3]

hmm, not sure if we are using PPPOE, but doing a ping test to a node in our USA server farm, I have to go as low as 1390 before no framentation. That doesnt include the ipsec stuff I have to add in and subtract from for the VPN tunnel. I was following this guide:  https://www.sonicwall.com/support/knowledge-base/set-mtu-in-vpn-environment-in-case-of-throughput-is...

and my math is showing like 1345 mtu I should be using based on that.

[Vanadiel · Accepted solution]

If you are using a Bell connection it would be using PPPOE.

I just checked mine to confirm:

Pinging 8.8.8.8 with 1464 bytes of data:
Reply from 8.8.8.8: bytes=1464 time=15ms TTL=115
Reply from 8.8.8.8: bytes=1464 time=15ms TTL=115
Reply from 8.8.8.8: bytes=1464 time=14ms TTL=115
Reply from 8.8.8.8: bytes=1464 time=15ms TTL=115

Ping statistics for 8.8.8.8:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 14ms, Maximum = 15ms, Average = 14ms

1464 Max packet size from Ping Test
+ 28 IP and ICMP headers
1492 is the optimum MTU Setting, which it what it shows in my router software.

I think maybe the confusion comes from the fact that the data packet is 1464, so when you ping you have to remove all the header data. It could also be caused by a wonky switch or router configuration fragmenting all your packets.