Solved

Is the VLAN mtu or port mtu that my 3560 switch is actually using?

Posted on 2013-02-05
4
2,136 Views
Last Modified: 2013-02-06
I setup port-channels on the 3560X switch with multiple vlan suport and set Jumbo MTU size to 9198.  VLAN mtu is 1500.  If two devices with jumbo frame enabled (mtu=9100) are connected to this switch and are on the same VLAN, which mtu size will they be using when talking to each other?   Thank you.
0
Comment
Question by:altonyoung
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
4 Comments
 
LVL 57

Expert Comment

by:giltjr
ID: 38857901
Simple answer, the jumbo size.

Explanation:

VLAN's don't have a MTU a VLAN interface does, ports do, and a etherchannel does.

A VLAN interface is only used when you are talking directly to the IP address for that VLAN interface.
0
 

Author Comment

by:altonyoung
ID: 38858187
giltjr,

Thanks for your reply.   So if two devices on the same VLAN, but different switches with jumbo frame enabled will also talk using the jumbo size since traffic won't need to be routed out of the vlan?  

Thank you very much again for your time.
0
 
LVL 9

Expert Comment

by:Sandeep Gupta
ID: 38858735
yes..ofcourse
0
 
LVL 57

Accepted Solution

by:
giltjr earned 500 total points
ID: 38858843
Yes, they will, assuming that the ports connecting the switches are also setup to support jumbo frames.

I also am assuming that you have setup the computers involved to use jumbo frames.  You do have to be careful if you are using Windows and the computers have two or more NIC's.

Based on my personal experience Windows will use the smallest MTU defined on any NIC no matter which NIC it is communicating over.  That is, if you have NIC1 MTU=1500 and NIC2 MTU=9000, Windows will use MTU of 1500 on both NIC's.  Don't ask me why, that is just what Windows 7 and XP did for me.
0

Featured Post

PeopleSoft Has Never Been Easier

PeopleSoft Adoption Made Smooth & Simple!

On-The-Job Training Is made Intuitive & Easy With WalkMe's On-Screen Guidance Tool.  Claim Your Free WalkMe Account Now

Question has a verified solution.

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

I had an issue with InstallShield not being able to use Computer Browser service on Windows Server 2012. Here is the solution I found.
WARNING:   If you follow the instructions here, you will wipe out your VTP and VLAN configurations.  Make sure you have backed up your switch!!! I recently had some issues with a few low-end Cisco routers (RV325) and I opened a case with Cisco TA…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
There's a multitude of different network monitoring solutions out there, and you're probably wondering what makes NetCrunch so special. It's completely agentless, but does let you create an agent, if you desire. It offers powerful scalability …
Suggested Courses

696 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