Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements
Webcast-Catalyst9k
New Member

Broadcast large UDP datagrams between VLANs

Hello,

I wish to broadcast large UDP packets between two VLANs (on the one set of stacked 3750 switches).
 
I have setup an ip helper which allows me to broadcast between vlans. That works fine, but I am limited to datagrams around 5912 bytes in size.
 
I want to be able to broadcast larger datagrams.
 
I can successfully broadcast larger datagrams (65000-ish bytes) within the one vlan, but not between two vlans.
 
Am I able to increase the size of broadcast UDP datagrams between vlans and if so, how?
 
Thanks in advance.
Everyone's tags (1)
2 REPLIES
Super Bronze

DisclaimerThe Author of this

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Hmm, I'm wondering whether a helper cannot forward fragments.

If not, if you enable jumbo support on the 3750, you might be able to send larger diagrams, but perhaps not larger than MTU.

New Member

Thanks Joseph,Wireshark

Thanks Joseph,

Wireshark informs me that datagrams less than around 5912 bytes are fragmented and reassembled between VLANs successfully by the helper.

Jumbo frames are enabled on the 3750's with an MTU of 1500.  I'll up this to 9000 to see if it makes a difference.

 

Thanks,

JC

133
Views
0
Helpful
2
Replies
CreatePlease to create content