TCP Window Scaling issue

Larry Sheldon LarrySheldon at cox.net
Fri Jul 25 02:13:47 UTC 2014


[Sorry about the null reply.]
On 7/24/2014 11:51 AM, Zach Hill wrote:
> Also just to reiterate I would lean more heavily on something fishing in
> the WAN cloud if all traffic from Site 1 to Site 2 were not seeing tcp
> window scaling properly, however it's only for Server A that is seeing
> this. Server A is able to properly TCP window scale for any local traffic.

I don't have enough data to make a detailed guess, but the broad brush 
is that on A, B, the router A talks to, the router B talks to, or a 
router in the path has got an ACL that knows A's IP or MAC address that 
has an unplanned affect.

I'd turn off all ACL's on the path and check again and if clear, turn 
them back on one at a time.  It is not going to be something you 
intended to do.

One other possibility--traffic not routed by most direct, fire-wall-free 
route, but being detoured through a firewall.
-- 
Requiescas in pace o email           Two identifying characteristics
                                         of System Administrators:
Ex turpi causa non oritur actio      Infallibility, and the ability to
                                         learn from their mistakes.
                                           (Adapted from Stephen Pinker)


More information about the NANOG mailing list