[c-nsp] Adjusting MTU on 802.1q links

[Roger Wiklund]

On Fri, Dec 3, 2010 at 2:49 PM, Matthew Huff <mhuff at ox.com> wrote:
> I don't know why it never occurred to me, but on 802.1q trunk links, non-native vlans are encapsulated within 802.1q headers, therefore max packets would have to be fragmented. On trunks that support it, should standard practice to bump up the mtu on both sides to account for the 802.1q header. If so, what are the downsides?

Thats not needed, try to ping with 1500bytes  with flag do not
fragment and you will see that it works.
Only time you need to increase MTU is for QinQ, MPLS etc.

Take a look at this page:

http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a00801350c8.shtml#topic2