Routing

Hi, 

For an MPC-3D-16XGE-SFPP installed on an MX960 with SCBE-MX-S it seems we can't use all the 16 ports i.e. we will lose redundancy and/or failover or have problems with these. I heard there is/was a KB for this. Running on 11.4.

If someone has come across this maybe share the knowledge? 🙂

If someone could point me out to this KB as I couldn't seem to find it in my searches?

Thanks..

Hello,

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@famz wrote:

Hi, 

 

For an MPC-3D-16XGE-SFPP installed on an MX960 with SCBE-MX-S it seems we can't use all the 16 ports i.e. we will lose redundancy and/or failover or have problems with these. 

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"Lose redundancy" and "can't use" are 2 very different things in my book.

You CAN use all 16 ports on this card. However, how do You use them depends on Your specific needs.

This card has 4 groups of 4 10GE ports in each group.

With at least 2 installed & working SCBEs in a MX960 chassis, all 16 ports on this card can simultaneously forward trafic at close-to-line rate (exact rate depends on packet size).

With single SCBE, this card does not have fabric redundancy but this is true for any card.

HTH

Thanks
Alex

Hi Alex,

Excellent! That's what I expected. I was just looking to confirm that indeed there is/isn't a KB out mentioning something like this.

May I ask what the max number of MPC cards we can install on an MX960 and fully use all the 16 ports? Ofcourse take into consideration dependencies and redundancy

3 SCBE installed, 2 RE-S-200.

Regards,

Famz..

Hello,

There is no HW or SW restrictions I know of to disallow 11 MPC-3D-16XGE-SFPP in MX960 chassis.

In practice, the max number of MPCs depend not only on the number of SCBE installed but also on number of Power Entry Modules (PEM) installed and PEM type (AC, DC, High Capacity AC or High Capacity DC) and ambient temperature (the higher the temp, the more watts are consumed by cards)

The max practical number of MPC does not directlly depend on the Routing Engine model, rather inderectly (via power budget calcs)

I suggest You engage Your nearest friendly Juniper Systems Engineer to look at all possible card+PEM scenarios for You.

HTH

Thanks
Alex

Many thanks Alex. Clear enough!

Regards,

Famz.

MX960 has two fabric cards (SCBs) by default and a third can be installed for redudancy.  If you have dual REs, then you should have three SCBs.

DPCs only use two of the SCBs with the third acting as a spare.  MPCs use all three; that is where the lack of SCB redundancy comes into play.  Loss of a SCB will not take the MPCs offline, nor any of the ports.  Instead, what happens is the overall capacity is reduced which means each block of 4x10G ports will no longer be able to run at full 40 Gbps.  Instead, they will be able to run at ~27 Gbps.

See KB23065 for a nice explanation of the switch fabric.  The bottom of the page provides a summary that provides the above info.

-Chad

Hello,

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@ChadM wrote:

 

 

See KB23065 for a nice explanation of the switch fabric.  The bottom of the page provides a summary that provides the above info.

 

-Chad

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This KB article refers to and describes SCB, not SCBE. Specifically, in MX960 chassis with 3 SCBEs and MPCs, where SCBE in slot 2 acts as backup by default, if 1 SCBE goes offline, the fabric operating capacity is NOT reduced. It is still the case for MX960 with 3 active SCB and MPC, where upon 1 SCB going offline the fabric operating capacity per PFE goes down from 40 to 27Gbps.

https://www.juniper.net/techpubs/en_US/release-independent/junos/topics/concept/enhanced-mx-scb-description-mx960.html 

HTH

Thanks
Alex

Good point Alex!  You are correct, I didn't read close enough to see SCBE.

Thank you for catching that!

- Chad