cancel
Showing results for 
Search instead for 
Did you mean: 

Hey! What's with the PTP 820C 4+0 XPIC BOM?

Moderator

Hey! What's with the PTP 820C 4+0 XPIC BOM?

Good grief!

 

I’ve been asked these questions four times in about a week’s time.

 

Let’s nip this in the bud.

 

What’s with the PTP 820C 4+0 XPIC BOM?

 

What’s with all of the fiber gear?

 

What’s with the protection cables?

 

We need to enhance LINKPlanner.

 

Until then, here are the questions you have to ask when you’re designing a PTP 820C 4+0 link:

 

  1. What’s the link length? (short or long?)

 

  • If it’s a short link, you’re probably trying to get 4 Gbps or more out of the link. You won’t be using internal LAG or MC-ABC for this (Remember that combining traffic internally within the PTP 820C using LAG and/or MC-ABC limit the total overall throughput to what a GigE port can carry: ~1 Gbps.) You’ll be running at least four Ethernet cables from the PTP 820C boxes down the tower into the telecommunications shack at each link end.
  • If it’s a long link, you’re probably trying to get a 1 Gbps link to work over a long distance. (Two PTP 820C boxes at each end of a link allow you to divide the 1 Gbps into four 250 Mbps links, which allows you to reduce the modulation mode and increase the availability.) You might use internal LAG or MC-ABC for this. If the link’s total throughput isn’t greater than 1 Gbps, you can combine each link’s traffic inside the PTP 820C using MC-ABC, and you’ll be running at least two Ethernet cables from the PTP 820C box down the tower into the telecommunications shack at each end.

 

  1. Does the switch in your telecommunications shack support mixed media? That is, can you combine traffic from a fiber cable and a copper Ethernet cable? (We suspect that you can’t. It’s probably best that you keep your cabling all copper Ethernet or all fiber. Don’t mix your media.) Remember that the PTP 820C only has one SFP port that you can use for fiber, and that port is limited to 1 Gbps. If you’re planning to combine the copper port and the SFP port, make the SFP port a copper port.

 

  1. Are you planning to manage the PTP 820C with in-band management or out-of-band management?

 

  • If you plan to use in-band management, how do you plan to combine your traffic? Remember that in general, you can’t manage network elements behind a switch that’s providing link aggregation. (In layman’s terms, the switch decides which pipe should carry the traffic. What if the switch decides that your NM traffic should be carried by a pipe that doesn’t connect to the box you’re trying to manage?) Depending upon your switch, you might be able to use Mate Management Access and Automatic State Propagation to manage the two PTP 820C boxes with in-band management. (This is why LINKPlanner includes the protection management and protection management ODU splitter cables—so you can use in-band management.)
  • If you plan to use out-of band management, remember that you’ll need surge suppression at the top and bottom of this cable. (The PTP 820C built-in surge suppression only applies when ETH1 is used for data and power.)

 

  1. Are you planning to use external DC or Power over Ethernet (PoE) via ETH1?

 

  • If you’re going to use external DC, all of your copper Ethernet cables require surge suppression at the top and bottom of the tower.
  • If you’re going to use PoE via ETH1, you can take advantage of the PTP 820C’s built-in surge suppression on ETH1.

 

Here are the three link types that you’ll probably use:

 

Short Link, combine traffic at the shack, out-of-band management, PoE

PoE via ETH1, copper SFP module in ETH2, PoE injector, and three copper Ethernet cables per PTP 820C box. Four surge suppressors per PTP 820C box, two at the top of the tower, and two at the bottom of the tower. (Remember that ETH1 and PoE injector have built-in surge suppression.)

 

So in total, that’s four (4) copper SFP modules, four (4) PoE injectors, twelve (12) copper Ethernet cables, four PTP 820C boxes, and sixteen (16) surge suppressors for the link. Yes, that’s a lot of equipment, but the link will carry more than 4 Gbps!

 

Long link, MC-ABC, combine traffic at the shack, out-of-band management, external DC

External DC cable, fiber SFP module in ETH2, MNG copper Ethernet cable, external DC power supply, and one fiber Ethernet cable per PTP 820C box. Two (2) surge suppressors per PTP 820C box, for the MNG cable, one at the top of the tower, and one at the bottom of the tower.

 

So in total, that’s four (4) fiber SFP modules, four (4) MNG Ethernet cables, four (4) fiber Ethernet cables, four (4) PTP 820C boxes, eight (8) surge suppressors, and lots of external DC cabling for the link. Note that you probably also need SFP modules for your external switch.

 

Long link, MC-ABC, combine traffic at the shack, out-of-band management, PoE

PoE via ETH1, MNG copper Ethernet cable, PoE injector, and two copper Ethernet cables per PTP 820C box. Two surge suppressors per PTP 820C box, for the MNG cable, one at the top of the tower, and one at the bottom of the tower.

 

So in total, that’s four (4) PoE injectors, four (4) MNG Ethernet cables, four (4) copper Ethernet cables, four (4) PTP 820C boxes, eight (8) surge suppressors. Note that you probably also need SFP modules for your external switch.

 

If you’re VLAN, LAG, etc. savvy, you can probably easily configure your switches to support in-band management for the two long link options. (In-band management eliminates the need for the surge suppressors and management cables.)

 

If you’re exceptionally network savvy and you’re willing to configure both your external switches and your PTP 820C boxes with MMA and ASP (Mate Management Access and Automatic State Propagation), you can use in-band management for the short link. (Again, in-band management eliminates the need for the surge suppressors and management cables.)

 

Bring on the corrections, observations, and questions!

 

Dave

1 REPLY
Cambium Employee

Re: Hey! What's with the PTP 820C 4+0 XPIC BOM?

Thanks, Dave!

In my opinion, the most common use of 4+0 (2x2+0) would be for high capacity. Since LINKPlanner assumes the "long link" scenario a few manual changes are required to adjust the autogenerated BOM for the "short link" high throughput scenario. I've also attached a full 11GHz PTP820C Wideband 2x2+0 XPIC (aka 4+0) BOM for reference. 

 

Basically, the following changes are needed:

- Delete all fiber runs and parts

- Remove the DC connector and DC cables unless external power is desired

- Add a PoE injector per PTP820C unless external power is desired

- Replace fiber SFP with copper SFP

- Add sufficient Cat5 cable drums for three Cat5 cables per PTP820C radio - the three runs are for ETH1, ETH2, and MGT

- Add ALPU-F140 non-Cambium surge suppressors for non-powered Cat5 runs

 

Once those changes are made you'll have a correct BOM for your deployment!

 

If fiber runs are desired over copper runs then external power will be required and the PTP820C will need to be special ordered so that ETH3 can be used for data. ETH3 is reserved for MIMO on standard PTP820C radios and for two fiber runs per PTP820C in this scenario both SFP ports (ETH2 and ETH3 ports) would be used. Cat5 cable will still be required for out of band management. 

 

If narrowband radios are used instead of wideband radios then the total throughput will be under a gigabit. That will preclude the need for a second data run and it will also allow for in-band management since there is only one data run. MC-ABC (physical layer link aggregation) will then be used instead of adding a second data run and only one Cat5 run will be required for PoE, data, and in-band management. This would be the simplest implementation. The difference from the bullet points above then would be to add MC-ABC and delete the second GE port license, delete SFP's, and only provision Cat5 cable for one run per PTP820C.