Discussion:
[Linuxptp-devel] Value of physicalLayerProtocol in standard?
Geoff Salmon
2013-02-08 15:06:26 UTC
Permalink
Hi

Can anyone shed some light on what values the physicalLayerProtocol
field in CLOCK_DESCRIPTION management messages can have? All I get from
the standard is Section 15.5.3.1.2.2 saying it "shall indicate the
physical layer protocol".

thanks,
Geoff
Richard Cochran
2013-02-08 15:16:15 UTC
Permalink
Post by Geoff Salmon
Hi
Can anyone shed some light on what values the physicalLayerProtocol
field in CLOCK_DESCRIPTION management messages can have? All I get from
the standard is Section 15.5.3.1.2.2 saying it "shall indicate the
physical layer protocol".
"Ethernet" ?

"IEEE 802.3" ?

Maybe it is just a freely chosen string.

Thanks,
Richard
Richard Cochran
2013-02-08 17:01:19 UTC
Permalink
Post by Geoff Salmon
Hi
Can anyone shed some light on what values the physicalLayerProtocol
field in CLOCK_DESCRIPTION management messages can have? All I get from
the standard is Section 15.5.3.1.2.2 saying it "shall indicate the
physical layer protocol".
FWIW, my OTMC 100 answers this query with "IEEE 802.3".

If you have access to some other commerical PTP products, you might
just see how they answer the query. I patched the pmc, below, and then
watched for the reply in wireshark.

HTH,
Richard
---
diff --git a/pmc.c b/pmc.c
index 5e000bb..620ff1a 100644
--- a/pmc.c
+++ b/pmc.c
@@ -86,7 +86,7 @@ struct management_id idtab[] = {
{ "TIME_STATUS_NP", TIME_STATUS_NP, do_get_action },
/* Port management ID values */
{ "NULL_MANAGEMENT", NULL_MANAGEMENT, null_management },
- { "CLOCK_DESCRIPTION", CLOCK_DESCRIPTION, not_supported },
+ { "CLOCK_DESCRIPTION", CLOCK_DESCRIPTION, do_get_action },
{ "PORT_DATA_SET", PORT_DATA_SET, do_get_action },
{ "LOG_ANNOUNCE_INTERVAL", LOG_ANNOUNCE_INTERVAL, not_supported },
{ "ANNOUNCE_RECEIPT_TIMEOUT", ANNOUNCE_RECEIPT_TIMEOUT, not_supported },
@@ -248,6 +248,9 @@ static void pmc_show(struct ptp_message *msg, FILE *fp)
tsn->gmPresent ? "true" : "false",
cid2str(&tsn->gmIdentity));
break;
+ case CLOCK_DESCRIPTION:
+ fprintf(fp, "CLOCK_DESCRIPTION ");
+ break;
case PORT_DATA_SET:
p = (struct portDS *) mgt->data;
if (p->portState > PS_SLAVE) {
Geoff Salmon
2013-02-08 18:57:47 UTC
Permalink
On 13-02-08 12:01 PM, Richard Cochran wrote:> On Fri, Feb 08, 2013 at
Post by Richard Cochran
Post by Geoff Salmon
Hi
Can anyone shed some light on what values the physicalLayerProtocol
field in CLOCK_DESCRIPTION management messages can have? All I get from
the standard is Section 15.5.3.1.2.2 saying it "shall indicate the
physical layer protocol".
FWIW, my OTMC 100 answers this query with "IEEE 802.3".
If you have access to some other commerical PTP products, you might
just see how they answer the query. I patched the pmc, below, and then
watched for the reply in wireshark.
Oh, of course. Good idea. I have a Meinberg lantime M600 here that also
replies with "IEEE 802.3".

- Geoff

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