Hi,
I'm looking for an IEEE 1588v2/PTP aware switch. Looking around, I've found several ruggadized ones and a couple in office types. I only need something for use in office, and something with 16 or 24 GigE ports would work.
The ones I've found are pretty expensive, considering we would need 4 of them.
Gerald
On 2019-12-02 11:42, Gerald Brandt wrote:
Hi,
I'm looking for an IEEE 1588v2/PTP aware switch. Looking around, I've found several ruggadized ones and a couple in office types. I only need something for use in office, and something with 16 or 24 GigE ports would work.
The ones I've found are pretty expensive, considering we would need 4 of them.
Yes, PTP support is generally limited to Enterprise / Industrial / ISP grade equipment. Some of which can be found used, if you're willing to go that route.
Otherwise, have a look at: https://www.nist.gov/el/intelligent-systems-division-73500/ieee-1588-product... https://en.wikipedia.org/wiki/List_of_PTP_implementations
and this fellow's experience, which seems to mirror yours: https://www.reddit.com/r/networking/comments/568xax/new_to_ptp_ieee_1588_hav...
I can tell you from direct experience that the two lists I linked above are FAR from comprehensive. You can, with a bit of work, find pages like this: https://gtacknowledge.extremenetworks.com/articles/Q_A/What-Timing-Protocols... from each major vendor.
An alternative is to use a cheap server (Atom-based is fine) with two server-class NICs in it, and run a PTP bridge, see below.
Also, if there's a straight layer-2 path from the end station that consumes PTP time, to the Grandmaster, the intermediate switches DO NOT have to be PTP boundary clocks. The PTP protocol can compensate for non-PTP transparent switches/bridges between the consumer and the Grandmaster. You can lose a small amount of accuracy (sub-millisecond) but that's still good enough for many/most scenarios. NOTE: this is not a guarantee; YMMV; circumstances may vary.
Where you would need a Boundary Clock is, for example, to retransmit PTP time onto a different VLAN than you received it on. This is, AFAICT, why PTP-capable switches exist... you'll note that most PTP-capable products are high-end because they're actually *routing* switches, and the L2 path to the Grandmaster is broken when you cross a router hop. That's where a cheap server can come in handy, it can rebroadcast PTP time received on one VLAN onto others. Again, you'll lose accuracy & precision simultaneously (no more 5ns sync!) but you'll get something.
Finally, the $64,000 question would be why you need to use PTP in the first place? Properly configured NTP can keep (non-Windows) systems in sync to within about 3msec on a LAN, including local router hops. The only
I'm pushing to get PTP capability at MBIX, but that's because I already happen to run mostly PTP-capable gear, it doesn't add much to MBIX's cost, so hey why not! MBIX members wouldn't be required to get PTP-capable equipment: if this happens, I think it would just be a thing that's magically available on the IX fabric if your gear knows how to listen for it. I think.
-Adam
On 2019-12-02 12:39 p.m., Adam Thompson wrote:
On 2019-12-02 11:42, Gerald Brandt wrote:
Hi,
I'm looking for an IEEE 1588v2/PTP aware switch. Looking around, I've found several ruggadized ones and a couple in office types. I only need something for use in office, and something with 16 or 24 GigE ports would work.
The ones I've found are pretty expensive, considering we would need 4 of them.
Yes, PTP support is generally limited to Enterprise / Industrial / ISP grade equipment. Some of which can be found used, if you're willing to go that route.
Otherwise, have a look at: https://www.nist.gov/el/intelligent-systems-division-73500/ieee-1588-product...
https://en.wikipedia.org/wiki/List_of_PTP_implementations
and this fellow's experience, which seems to mirror yours: https://www.reddit.com/r/networking/comments/568xax/new_to_ptp_ieee_1588_hav...
I can tell you from direct experience that the two lists I linked above are FAR from comprehensive. You can, with a bit of work, find pages like this: https://gtacknowledge.extremenetworks.com/articles/Q_A/What-Timing-Protocols... from each major vendor.
An alternative is to use a cheap server (Atom-based is fine) with two server-class NICs in it, and run a PTP bridge, see below.
Also, if there's a straight layer-2 path from the end station that consumes PTP time, to the Grandmaster, the intermediate switches DO NOT have to be PTP boundary clocks. The PTP protocol can compensate for non-PTP transparent switches/bridges between the consumer and the Grandmaster. You can lose a small amount of accuracy (sub-millisecond) but that's still good enough for many/most scenarios. NOTE: this is not a guarantee; YMMV; circumstances may vary.
I think what we're looking for is a switch with PTP Transparent Clock. Currently, the PTP packet goes through three switches (ugh, I know) to get from engineering to verification. One switch is in engineering to get all their equipment hooked up, that goes to the server room, with goes to verification with their own switch for their equipment. It's all the same network. We get enough lag that the PTP time differential affects our testing. We can do most of our testing with IRIG, but our clients will want PTP at some point. Going through a single switch helps, but it may be cheaper to get PTP Transparent Clock switches then it would be to get multiple new network drops through out the building. (we're pricing that out).
Where you would need a Boundary Clock is, for example, to retransmit PTP time onto a different VLAN than you received it on. This is, AFAICT, why PTP-capable switches exist... you'll note that most PTP-capable products are high-end because they're actually *routing* switches, and the L2 path to the Grandmaster is broken when you cross a router hop. That's where a cheap server can come in handy, it can rebroadcast PTP time received on one VLAN onto others. Again, you'll lose accuracy & precision simultaneously (no more 5ns sync!) but you'll get something.
Finally, the $64,000 question would be why you need to use PTP in the first place? Properly configured NTP can keep (non-Windows) systems in sync to within about 3msec on a LAN, including local router hops. The only
Industry/Client demand. PTP is specced in RFCs.
I'm pushing to get PTP capability at MBIX, but that's because I already happen to run mostly PTP-capable gear, it doesn't add much to MBIX's cost, so hey why not! MBIX members wouldn't be required to get PTP-capable equipment: if this happens, I think it would just be a thing that's magically available on the IX fabric if your gear knows how to listen for it. I think.
-Adam
On 2019-12-02 Gerald Brandt wrote:
Hi,
I'm looking for an IEEE 1588v2/PTP aware switch. Looking around, I've
Adam is right, looks like Netgear has affordable models that *might* work for you.
S3300 / 28 ports
https://www.netgear.com/business/products/switches/smart/S3300-28X.aspx#tab-...
That model says it supports 802.1AS and the Netgear manuals seem to indicate that 802.1AS gets you 1588/PTP (not sure about v2 though, but some mentions of that also in the forums). You'd need to confirm that is true though.
Through my suppliers it looks like I can sell that switch around $750, less in qty, so it is indeed affordable if it can do what you want, and it has plenty of additional high-end features.
According to Netgear, the only switch they provide that support PTP are the M4300 series, except for the 48 port versions). They support transparent clock.
Gerald
On 2019-12-04 7:06 a.m., Trevor Cordes wrote:
On 2019-12-02 Gerald Brandt wrote:
Hi,
I'm looking for an IEEE 1588v2/PTP aware switch. Looking around, I've
Adam is right, looks like Netgear has affordable models that *might* work for you.
S3300 / 28 ports
https://www.netgear.com/business/products/switches/smart/S3300-28X.aspx#tab-...
That model says it supports 802.1AS and the Netgear manuals seem to indicate that 802.1AS gets you 1588/PTP (not sure about v2 though, but some mentions of that also in the forums). You'd need to confirm that is true though.
Through my suppliers it looks like I can sell that switch around $750, less in qty, so it is indeed affordable if it can do what you want, and it has plenty of additional high-end features. _______________________________________________ Roundtable mailing list Roundtable@muug.ca https://muug.ca/mailman/listinfo/roundtable
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