RE: system mtu setting for DOiT lab 4

From: Michael Zuo (mzuo@ixiacom.com)
Date: Tue Feb 27 2007 - 23:33:30 ART


Ahhh, I found out that the "ip mtu 1500" is not a typo. The solution is
setting the system mtu to 1504 also but selectively setting mtu for some
vlans back to 1500.

But I still have the 2nd question: is there any ill effect having the
mtu 4 bytes too big (of course, assuming OSPF adjacency will be taken
care of with "mtu-ignore")

thanks

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Michael Zuo
Sent: Tuesday, February 27, 2007 6:02 PM
To: ccielab@groupstudy.com
Subject: system mtu setting for DOiT lab 4

hi group,

i ran into an issue doing DOiT lab 4. this lab requires configuration of
dot1q tunnel on switch ports and the solution mentioned that i should
configure "ip mtu 1500" on the vlan SVI interfaces. however, from the
DocCD section on dot1q tunnel, Cisco is recommending setting system mtu
to 1504 because of the 4 extra bytes used by dot1q tunnel.

anyone knows if the DOiT lab solution has a typo?

also, in a lab test environment, is there any negative effects of
setting global "system mtu" instead of per interface "ip mtu"?

thanks a lot



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