On 22/09/2008, at 2:22 PM, Nathan Ward wrote:
I wonder, is it feasible that the > 1518b frames are eBGP, or
something else that's relevant only to that link?
If you use large frames then you need to ensure either everyone is consistent or that you have the ability to specifically say which peer is what MTU, otherwise you'll find BGP doesn't work because usually the BGP frames are the same as the router's max segment size for the interface. (I've screwed this up on an occasion with a private peering session - it LOOKS like it should work, but doesn't).
The difference being that there would be no customer frames > 1518,
just network stuff.
I guess this is the key - is anyone running >1518 to customers? If not, then the net effect isn't going to be huge.
It's 0.12% of total packets.
Is it really that high? A very quick look at our network shows it's closer to 0.0005% of packets on external links.