[c-nsp] Performance issue on link

CiscoNSP List cisconsp_list at hotmail.com
Mon Apr 1 19:49:33 EDT 2013


Thanks Arie - I already have the following policy-maps on each router:

policy-map 40MBPS
 class class-default
    police 41943040 5242880 conform-action transmit  exceed-action drop 

Then on the L3 Ints between the POP's

service-policy input 40MBPS
service-policy output 40MBPS

Should I be shaping rather than policing?  

> From: avayner at cisco.com
> To: cisconsp_list at hotmail.com; cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] Performance issue on link
> Date: Mon, 1 Apr 2013 23:20:34 +0000
> 
> You need to shape your traffic to 40Mbps (or most likely slightly less than that).
> TCP bursts and your provider drops the traffic, which causes the TCP window to shrink.
> 
> Your switches cannot shape, so you would have to do it on the routers.
> 
> Basically, a classic sub-rate link problem:
> http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND_40/QoSIntro_40.html#wp61026
> 
> Arie
> 
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of CiscoNSP List
> Sent: Monday, April 01, 2013 15:51
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Performance issue on link
> 
> Hi,
> 
> We have a 40Mb link between 2 POPs - Latency ~65m/sec (No packet-loss)
> 
> POP A Is a 7301 and 2960POP B is a 7200 and 4948
> 
> 40Mb link is connected to the two switches (L2), and then a trunk link to both routers for all L3.
> 
> Have a Linux server connected to both switches, and achieve the following performance:
> 
> IPERF (UDP)
> POP A -> POP B - 38.5Mb/secPOP B -> POP A - 38.5Mb/sec
> 
> IPERF (TCP)
> POP A -> POP B - ~20Mb/secPOP B -> POP A - ~12Mb/sec
> 
> FTP
> POP A -> POP B - ~38Mb/secPOP B -> POP A - ~16Mb/sec
> 
> WGET
> POP A -> POP B - ~30Mb/sec POP B -> POP A - ~16Mb/sec
> 
> Any suggestions on why I am seeing poor performance with TCP transfers? (Especially POP B -> POP A direction) - I've tried adjusting the window size in IPERF but it actually made the results worse?
> Thanks in advance.
> 
> 
> 
>  		 	   		  
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