[AusNOG] NBN Q

[Matt Carter]

Yes but the other carriers aren’t enforcing the aggressive PBS values that NBNCo are at the NNI and arbitrary PBS values at the UNI-D (regardless of rate) . The big problem with NBN services has nothing to do with policing as a concept but rather the sharp burst values that NBNCo are using for their policing and that they are being applied on AVCs which have quite often very little flows going across them. At the NNI they say they will police at 10ms PBS on TC-4 but in my experience an Alcatel 10ms is more like a Cisco 4ms and unless you have an ASR or some other platform that can perform shaping in hardware to millisecond values you are going to have a really tough time passing certification because within the timing interval you will have instantaneous bursts that exceed the NBN policers so you need to get that timing interval down really really low in order to stay under the NBNco policer. We’ve settled on 1ms and 100ms of queue-depth which seems to work nicely for customers who can’t implement their own AVC shaping in hardware

As a side note, anyone seeing broken DHCP on NBNCo tails ?? I’ve now got a number of AVCs across multiple downstream RSPs where by the deployed CPE is configured with IP helper for LAN stations and the return DHCPOFFER goes into the NNI and doesn’t come out at the CPE. This happens on packets which are natively encapsulated (S/C-TAG) and DHCPOFFER’s which  are encapsulated in a PPPoE session!! PCAP shows packets go to the NNI as expected with the expected Cos/Tos (0) and what looks like a perfectly legitimate response just never arrives at the CPE. I’ve seen a customer deploy the same CPE template on 6 tails and 2 of them just can’t get IP helper working the DHCPOFFER is sent but it never pops out at the CPE. One downstream RSPs cites they have multiple services with two different wholesale NBN providers and they have circuits on both wholesalers which are exhibiting this issue so it would appear the issue perverse across multiple NBN NNIs and multiple NBN AVCs.. (RSP is a highly competent industry provider and has provided PCAPs which correspond with my findings.) Anyone else seeing this oddity ??





From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Tony
Sent: Wednesday, 14 October 2015 9:57 AM
To: paul+ausnog at oxygennetworks.com.au; Tim Jones; ausnog at lists.ausnog.net
Subject: Re: [AusNOG] NBN Q

What NBN are doing is the same as every other carrier out there (policing, not shaping). We have more trouble with services from another carrier that are terminated using an MRV brand CPE device that has exceedingly small buffers for any kind of bursts and seems to choke when you go over the burst parameter so that instead of getting policed to the correct speed, you get about 10% of the speed until it recovers a few seconds later.


regards,
Tony


________________________________
From: "paul+ausnog at oxygennetworks.com.au<mailto:paul+ausnog at oxygennetworks.com.au>" <paul+ausnog at oxygennetworks.com.au<mailto:paul+ausnog at oxygennetworks.com.au>>
To: 'Tim Jones' <tim at iseek.com.au<mailto:tim at iseek.com.au>>; ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>
Sent: Wednesday, 14 October 2015, 8:38
Subject: Re: [AusNOG] NBN Q

Yep, ISP is responsible for CVC and AVC shaping, NBN just drop packets like a bitch !

Regards
Paul


From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Tim Jones
Sent: Wednesday, 14 October 2015 9:28 AM
To: ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>
Subject: Re: [AusNOG] NBN Q

This is correct. NBN Co moved from queuing to policing some time ago. They advise access seekers should be performing per AVC and CVC shaping, otherwise you will experience throughout performance degradation.

There is a good NBN Co technical document “Queue to Policer based QOS Migrations - Consequences for EU Throughput” that you should be able to get from NBN Co or your  NBN wholesale partner.

Cheers,
Tim


From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Philip Loenneker
Sent: Wednesday, 14 October 2015 8:53 AM
To: ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>
Subject: Re: [AusNOG] NBN Q

As a kind of side note to this, I’ve heard that the traffic shaping method by NBN Co is less than ideal (I recall something about dropping packets instead of queuing but can’t remember details), and that ISPs should put traffic shaping rules on their own equipment to avoid performance issues on the links. I did a bit of a Google on the topic but am probably using the wrong terminology to find anything useful. Does anyone have any more information they could share on this?
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