?
Solved

Ethernet Circuit MTU

Posted on 2011-05-10
2
Medium Priority
?
505 Views
Last Modified: 2012-05-11
Hi

We're experiencing some wierdness with our network - a brief overview;

We have 2 sites (within 50 miles) using the same ISP, same firewall hardware.  MTU's on each device (switch, firewall etc) is set to 1500 but when we perform ping IP -f -l MTU we get fragmented packets for any MTU value over 1272.

Also, all sites we communicate with (32 sites worldwide) we're gettig the same response with over MTU 1272.

Is this normal? Should we be shouting at the ISP?

Clearly if the MTU is low, then we're getting less for our buck..?

Thanks
0
Comment
Question by:jasonhamlett
2 Comments
 
LVL 9

Accepted Solution

by:
Michael Knight earned 2000 total points
ID: 35730687
It's probably just the route. I mean every node that the transmission is going through is going to have and modify the MTU where possible according to the Path MTU Discovery 'protocol'. Meaning the entire route/path is going to be 'discovered' and adjusted to lowest MTU for any device that the packet will encounter. Forcing a 1500 would then of course become fragmented.
1272 does seem low, but it's most likely a failsafe low. If you wanted to control the MTU outside your network you'd have to control every hop.
0
 

Author Closing Comment

by:jasonhamlett
ID: 36559705
got me thinking in the right direction...
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Preface There are many applications where some computing systems need have their system clocks running synchronized within a small margin and eventually need to be in sync with the global time. There are different solutions for this, i.e. the W3…
Configuring network clients can be a chore, especially if there are a large number of them or a lot of itinerant users.  DHCP dynamically manages this process, much to the relief of users and administrators alike!
This video shows how to quickly and easily deploy an email signature for all users in Office 365 and prevent it from being added to replies and forwards. (the resulting signature is applied on the server level in Exchange Online) The email signat…
This lesson discusses how to use a Mainform + Subforms in Microsoft Access to find and enter data for payments on orders. The sample data comes from a custom shop that builds and sells movable storage structures that are delivered to your property. …

839 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question