On Mon, Jun 22, 2020 at 5:30 PM Hal Murray
wrote:
>
>
> How often do packets magically get duplicated within the network so that the
> target receives 2 copies? That seems like something somebody at NANOG might
> have studied and given a talk on.
>
> Any suggestions for other places to look?
b...@herrin.us said:
> NTP you say? How does iburst work during initial sync up?
How does it work, or how should it work? 1/2 :)
NTP has been around for a long time. It looks very simple, so anybody thinks
they can toss off an implementation without much thought. It will probably
work,
Am Montag, 22. Juni 2020, 23:53:44 schrieb William Herrin:
> On Mon, Jun 22, 2020 at 10:21 PM Saku Ytti wrote:
> > On Tue, 23 Jun 2020 at 08:12, William Herrin wrote:
> > > That's what spanning tree and its compatriots are for. Otherwise,
> > > ordinary broadcast traffic (like those arp packets)
On Tue, 23 Jun 2020 at 09:54, William Herrin wrote:
> There's a link in the chain you haven't explained. The packet which
> entered at S3 has a unicast destination MAC address. That's what was
> in the arp table. If they're following the standards, only one of PE1
> and PE2 will accept packets
On Mon, Jun 22, 2020 at 10:21 PM Saku Ytti wrote:
> On Tue, 23 Jun 2020 at 08:12, William Herrin wrote:
> > That's what spanning tree and its compatriots are for. Otherwise,
> > ordinary broadcast traffic (like those arp packets) would travel in a
> > loop, flooding the network and it would just
On Tue, 23 Jun 2020 at 09:32, Sabri Berisha wrote:
> Aaah yes, fair point! Thanks $deity for default timers that make no sense.
Add low-traffic connection and default 1024s maxPoll of NTP and this
duplication is guaranteed to happen for 97.9% of packets.
--
++ytti
- On Jun 22, 2020, at 11:21 PM, Saku Ytti s...@ytti.fi wrote:
Hi Saku,
> On Tue, 23 Jun 2020 at 09:15, Sabri Berisha wrote:
>
>> Yeah, except that unless you use static ARP entries, I can't come up
>> with a plausible scenario in which this would happen for NTP. Assuming
>> we're talking
On Tue, 23 Jun 2020 at 09:15, Sabri Berisha wrote:
> Yeah, except that unless you use static ARP entries, I can't come up
> with a plausible scenario in which this would happen for NTP. Assuming
> we're talking about a non-local NTP server, S3 will not send an NTP
> packet without first sending
- On Jun 22, 2020, at 10:21 PM, Saku Ytti s...@ytti.fi wrote:
Hi,
> Metro: S1-S2-S3-S1
> PE1: S1
> PE2: S2
> Customer: S3
> STP blocking: ANY
>
> S3 sends frame, it is unknown unicast flooded, S1+S2 both get it
> (regardless of which metro port blocks), which will send it via PE to
>
On 23/Jun/20 07:52, Saku Ytti wrote:
>
> S1-S2-S3-S1 is operator L2 metro-ring, which connects customers and
> 2xPE routers. It VLAN backhauls customers to PE.
Okay.
In 2014, we hit a similar issue, although not in a ring.
Our previous architecture was to interconnect edge routers via
On Tue, 23 Jun 2020 at 08:36, Mark Tinka wrote:
> To be clear, is the customer's device S3, or is S3 the ISP's device that
> terminates the customer's service?
S1-S2-S3-S1 is operator L2 metro-ring, which connects customers and
2xPE routers. It VLAN backhauls customers to PE.
--
++ytti
On 23/Jun/20 07:32, Saku Ytti wrote:
>
> Ring of 3 switches, minimum possible topology to explain the issue for
> people not familiar with L2.
To be clear, is the customer's device S3, or is S3 the ISP's device that
terminates the customer's service?
Mark.
On Tue, 23 Jun 2020 at 08:29, Mark Tinka wrote:
> In the above, is S3 part of the Metro-E ring, or simply downstream of S1
> and S2?
Ring of 3 switches, minimum possible topology to explain the issue for
people not familiar with L2.
--
++ytti
On 23/Jun/20 07:21, Saku Ytti wrote:
> Metro: S1-S2-S3-S1
> PE1: S1
> PE2: S2
> Customer: S3
> STP blocking: ANY
>
> S3 sends frame, it is unknown unicast flooded, S1+S2 both get it
> (regardless of which metro port blocks), which will send it via PE to
> Internet.
>
> STP doesn't help, at
On Tue, 23 Jun 2020 at 08:12, William Herrin wrote:
Hey Bill,
> That's what spanning tree and its compatriots are for. Otherwise,
> ordinary broadcast traffic (like those arp packets) would travel in a
> loop, flooding the network and it would just about instantly collapse
> when you first
On 23/Jun/20 06:41, Saku Ytti wrote:
>
> I can't tell you how common it is, because that type of visibility is
> not easy to acquire, But I can explain at least one scenario when it
> occasionally happens.
>
> 1) Imagine a ring of L2 metro ethernet
> 2) Ring is connected to two PE routers, for
On Mon, Jun 22, 2020 at 9:43 PM Saku Ytti wrote:
> I can't tell you how common it is, because that type of visibility is
> not easy to acquire, But I can explain at least one scenario when it
> occasionally happens.
>
> 1) Imagine a ring of L2 metro ethernet
> 2) Ring is connected to two PE
Hey Hal,
> How often do packets magically get duplicated within the network so that the
> target receives 2 copies? That seems like something somebody at NANOG might
> have studied and given a talk on.
I can't tell you how common it is, because that type of visibility is
not easy to acquire,
How often do packets magically get duplicated within the network so that the
target receives 2 copies? That seems like something somebody at NANOG might
have studied and given a talk on.
Any suggestions for other places to look?
Context is NTP. If a client gets an answer, should it keep
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