nanog mailing list archives
Re: TCP Window Scaling issue
From: Matthew Petach <mpetach () netflight com>
Date: Thu, 24 Jul 2014 10:23:33 -0700
On Thu, Jul 24, 2014 at 9:51 AM, Zach Hill <zach.reborn () gmail com> wrote:
Also just to reiterate I would lean more heavily on something fishy 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.
Remember, the WAN cloud is just that, a cloud; it's not likely to be a single link underneath it all; so one bad link/bad port/bad device in the cloud can affect just a sub-portion of the traffic, depending on the 5-tuple hashing that takes place. An interesting test would be to be give server A a different address (secondary address should be fine, all you need to do is source packets from a different source address) and see if your scaling suddenly reappears. If it does, it's definitely down to the 5-tuple hashing happening within The Cloud(tm). Matt
On Thu, Jul 24, 2014 at 12:47 PM, Zach Hill <zach.reborn () gmail com> wrote:Hi Machael, Let me setup another packet capture at each side to see if the initial packets are being modified at all. Thanks, On Thu, Jul 24, 2014 at 12:39 PM, Michael Brown <michael () supermathie net wrote:On 14-07-24 12:30 PM, Zach Hill wrote:Hi Tony. No firewall in the way. Physical flow is as below. Server A -> Nexus 7k -> 3845 router -> Sprint MPLS -> 3845 router ->Cisco3750x stack -> Server BI blame the cloud. Dump the actual packets as they leave Server A and arrive at Server B (and vice-versa!). Does it get modified en route? M. -- Michael Brown | The true sysadmin does not adjust hisbehaviourSystems Administrator | to fit the machine. He adjusts the machine michael () supermathie net | until it behaves properly. With a hammer, | if necessary. - Brian
Current thread:
- TCP Window Scaling issue Zach Hill (Jul 24)
- Re: TCP Window Scaling issue Tony Finch (Jul 24)
- Re: TCP Window Scaling issue Zach Hill (Jul 24)
- Re: TCP Window Scaling issue Michael Brown (Jul 24)
- Re: TCP Window Scaling issue Zach Hill (Jul 24)
- Re: TCP Window Scaling issue Zach Hill (Jul 24)
- Re: TCP Window Scaling issue Matthew Petach (Jul 24)
- Re: TCP Window Scaling issue Zach Hill (Jul 24)
- Re: TCP Window Scaling issue Valdis . Kletnieks (Jul 24)
- Re: TCP Window Scaling issue Zach Hill (Jul 24)
- Re: TCP Window Scaling issue Matthew Petach (Jul 24)
- Re: TCP Window Scaling issue Zach Hill (Jul 24)
- Re: TCP Window Scaling issue Zach Hill (Jul 24)
- Re: TCP Window Scaling issue Tony Finch (Jul 24)
- Message not available
- Re: TCP Window Scaling issue Larry Sheldon (Jul 24)
- Message not available
- Re: TCP Window Scaling issue Larry Sheldon (Jul 24)
- Re: TCP Window Scaling issue Roland Dobbins (Jul 24)
- Message not available
- Re: TCP Window Scaling issue Larry Sheldon (Jul 24)