[LUNI] Routers, MTU, and Comcast, oh my!

[Larry Garfield]

Kelly Martin wrote:

> If you're on a broadband provider that uses PPPoE, you do need to lower 
> your MTU to account for the PPPoE encapsulation overhead.  Otherwise 
> you'll be fragmenting at the router.  I think the overhead is 8 bytes, 
> making the MTU 1492.
> 
> As far as I know, Comcast is not using PPPoE anywhere in the Chicagoland 
> area, although there might be areas where they are that I don't know 
> about.  DOCSIS cable modem without PPPoE should be fine with the 
> standard 1500 Ethernet MTU.

Well they're not using PPPoE in my area at least, and my router is 
currently set to 1500.  So I guess my router just sucks after all.  The 
curious thing for me is that the same setup on RCN in another area had 
the same problem, but nowhere near to the same extent.

On RCN, I would get enough dropped packets that I couldn't do streaming 
media and often had one account on GAIM sign itself off periodically. 
If I plugged a system in directly, there was no trouble.  On Comcast, I 
always come back to find GAIM completely disconnected, and my Mozilla 
Mail on Win2k (different system) is usually jammed in mid-POP request so 
that it has to be closed and restarted to even work.  I don't know why 
there's such a drastic difference in performance degradation between the 
two, as they're both Cable modem systems.

-- 
Larry Garfield			AIM: LOLG42
larry at garfieldtech.com		ICQ: 6817012

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