nanog mailing list archives
Re: Long-haul 100Mbps EPL circuit throughput issue
From: alvin nanog <nanogml () Mail DDoS-Mitigator net>
Date: Thu, 5 Nov 2015 15:19:12 -0800
hi eric On 11/05/15 at 04:48pm, Eric Dugas wrote: ...
Linux test machine in customer's VRF <-> SRX100 <-> Carrier CPE (Cisco 2960G) <-> Carrier's MPLS network <-> NNI - MX80 <-> Our MPLS network <-> Terminating edge - MX80 <-> Distribution switch - EX3300 <-> Linux test machine in customer's VRF We can full the link in UDP traffic with iperf but with TCP, we can reach 80-90% and then the traffic drops to 50% and slowly increase up to 90%.
if i was involved with these tests, i'd start looking for "not enough tcp send and tcp receive buffers" for flooding at 100Mbit/s, you'd need about 12MB buffers ... udp does NOT care too much about dropped data due to the buffers, but tcp cares about "not enough buffers" .. somebody resend packet# 1357902456 :-) at least double or triple the buffers needed to compensate for all kinds of network whackyness: data in transit, misconfigured hardware-in-the-path, misconfigured iperfs, misconfigured kernels, interrupt handing, etc, etc - how many "iperf flows" are you also running ?? - running dozen's or 100's of them does affect thruput too - does the same thing happen with socat ?? - if iperf and socat agree with network thruput, it's the hw somewhere - slowly increasing thruput doesn't make sense to me ... it sounds like something is cacheing some of the data magic pixie dust alvin
Any one have dealt with this kind of problem in the past? We've tested by forcing ports to 100-FD at both ends, policing the circuit on our side, called the carrier and escalated to L2/L3 support. They tried to also police the circuit but as far as I know, they didn't modify anything else. I've told our support to make them look for underrun errors on their Cisco switch and they can see some. They're pretty much in the same boat as us and they're not sure where to look at.
Current thread:
- Long-haul 100Mbps EPL circuit throughput issue Eric Dugas (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue alvin nanog (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue Greg Foletta (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue Bob Evans (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue Pablo Lucena (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue Pablo Lucena (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue Theodore Baschak (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue William Herrin (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue Pablo Lucena (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue Pablo Lucena (Nov 05)
- Re: Long-haul 100Mbps EPL circuit throughput issue alvin nanog (Nov 05)