Does the PTP670/450i wireless link support redundancy? e.g. RSTP, ERPS, LACP and so on

Dear Support,

Does the PTP670/450i wireless link support redundancy? e.g. RSTP, ERPS, LACP and so on.

I will propose the wireless link for our customer. We need to keep the annual availability of at least 99.99% under the ITU-R rain climate with 1+1 redundancy for the wireless link(different frequency), from PC1 to PC2.

Network diagram like this:

I suppose the switch supports RSTP, ERPS and LACP. Which protocol do you suggest? and what setting is needed in the PTP450i? and how long is the recovery time for these three protocols?

Another question, How long is the suggested distance between the two PTP450i(different frequency) in the same building?

Thanks and regards,

I think what you need is LAG on the switch. By the way, Cambium cnMatrix supports LAG. You dont need the PTP670 to support any of those protocols. what you need is for PTP670 to transparently pass those traffic and we do just that.

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Dear Mr. Lin,

How long is the suggested distance between the two PTP450i(different frequency) on the same building floor? Or it doesn’t matter?

Thanks and regards,

Dear Mr.Lin,

Thank you for your reply.

Yes, we will propose cnMatrix TX2020R-P with dual PSU, but this switch does not support ERPS. I believe LACP is fit for us.


A few additional thoughts:

  • The redundancy scheme you illustrate in the original post is described as 2+0, meaning that two links are established concurrently between a pair of sites, and both of these links are carrying traffic. As Yonghao mentions above, this requires link aggregation in the switches. Operators use 2+0 either to increase capacity or provide redundancy in case of equipment failure.
  • Note that LINKPlanner calculates availability based on propagation over the planned path, and does not include unavailability due to hardware failure.
  • Rain attenuation is not normally a big problem in the 5 GHz bands, and it doesn’t contribute significantly to unavailability of a link. You can get confirmation of this by checking the link in LINKPlanner. Also, note that in a 2+0 scheme, rain attenuation would affect both links to an almost identical degree.
  • Standard Ethernet link aggregation attempts to distribute traffic evenly between links in the same group. It does this by identifying so-called conversations and allocating these to each link in turn. If your traffic consists of a large number of conversations, this is a useful approach. However, if the traffic consists of a small number of conversations with high traffic load (for example a few HD video feeds) then the distribution can be uneven, meaning that the effective capacity increase from 2+0 is less than double the capacity of one link.
  • You will need to consider RF interference between the two links. The links need to be on different channels (and not adjacent channels). In principle, it should be possible to achieve sufficient isolation between two ODUs at the same site by using high performance antennas and maintaining a large physical separation, but in most cases it is more practical to use TDD synchronization.
  • When configuring the PTP 670 ODUs, ensure that Data Port Wireless Down Alert is Enabled. This feature briefly disconnects the Ethernet port when the wireless link drops, so that the aggregation function in the switches responds promptly.
  • Consider how the PTP 670 ODUs will be managed. Link Aggregation will distribute management traffic randomly between the two links so that it may not reach the destination management agent. The most straightforward way to overcome this is to use local management over a separate drop cable to the Aux port.

Dear Thomas,

Thank you for your useful information.

Thanks and regards,