PTP 500 Link Capacity SNMP OID

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1

Hi everybody,

I'd like to know if there is a snmp OID for reading the current Link Capacity.

This value appears in the "Wireless" table, in "System Status" page on the PTP500 web management.

I did not find it in the MIB file I have.

Thanks in advance.

2

If I understand the question correctly, the MIB object you need is called aggregateDataRate. The OID for this object is is .1.3.6.1.4.1.17713.5.20.3. aggregateDataRate returns the sum of receiveDataRate and transmitDataRate.

3

Hello Mark,

thanks for your reply.

I think that aggregateDataRate is the effective traffic which is being transmitted from the radio. I have attached some screenshots to explain what I mean for "Link Capacity".

As you can see the aggregateDataRate is a bit lower than the Link Capacity (50.34 vs 50.68).

Maybe there is no OID for LinkCapacity but I'd really be happy if that oid is just not included in the MIB files...

Thanks in advance.

4

A nice screenshot always helps!

Transmit Data Rate and Receive Data Rate return the capacity of the link in the two directions. In other words, this is the maximum applied load that can be carried continuously without losing ethernet frames. These data rate attributes are a function of channel bandwidth, modulation mode, link symmetry and link range. The attribute names are maybe a bit misleading here, because these attributes do not indicate the offered or carried traffic.

There is a special case when the link operates with Adaptive symmetry. The Adaptive setting of Link Symmetry optimises symmetry based on offered traffic in two directions. For low levels of offered traffic it provides the lowest latency. For higher levels of traffic it provides increased capacity at the cost of somewhat higher latency. For asymmetric traffic, it provides asymmetric capacity.

Aggregate Data Rate, Transmit Data Rate and Receive Data Rate always relate to the present state of the adaptive operation. Link Capacity, on the other hand, indicates the maximum capacity that could be achieved with a large  bidirectional traffic load applied.

For fixed symmetry, Link Capacity and Aggregate Data Rate are interchangeable. As you have discovered, in adaptive symmetry there is sometimes a difference between Link Capacity and Aggregate Data Rate.

Does this help?

1 Like
5

Yes, Thank you Mark!