Support Support Downloads Knowledge Base Case Manager My Juniper Community

Knowledge Base

Search our Knowledge Base sites to find answers to your questions.

Ask All Knowledge Base Sites All Knowledge Base Sites JunosE Defect (KA)Knowledge BaseSecurity AdvisoriesTechnical BulletinsTechnotes Sign in to display secure content and recently viewed articles

[QFX] The Tx/Rx power windows of 40G QSFP+-40G-SR4 and 10G SR/USR do not line up

0

0

Article ID: KB31282 KB Last Updated: 01 Jun 2017Version: 2.0
Summary:

The Tx/Rx power windows of 40G QSFP+-40G-SR4 and 10G SR/USR do not line up. It is recommended to use channelized QFX-QSFP-40G-ESR4 for 4 x 10G break-out to be connected with 10G SFPs, not QFX-QSFP-40G-SR4.

Symptoms:

Topology

QFX5200-1 xe-0/0/53:0(QSFP+-40G-SR4)-----------------( SFP+-10G-SR)xe-0/0/44 QFX5100-2
xe-0/0/53:1 ----------------------------------------------------- xe-0/0/45
xe-0/0/53:2 ----------------------------------------------------- xe-0/0/46
xe-0/0/53:3 ----------------------------------------------------- xe-0/0/47


When connecting channelized interfaces (using QSFP+-40G-SR4) to peer 10G interfaces(SFP+-10G-SR), we may see rx power high warning on the peer SFP+-10G-SR.
 
admin@qfx5100-48s-01# run show interfaces diagnostics optics xe-0/0/4[4-7] |match "receive|rx power high warning|phys"
Physical interface: xe-0/0/44
Receiver signal average optical power : 0.9413 mW / -0.26 dBm
Laser rx power high warning : On
Laser rx power high warning threshold : 0.7943 mW / -1.00 dBm
Physical interface: xe-0/0/45
Receiver signal average optical power : 0.8930 mW / -0.49 dBm
Laser rx power high warning : On
Laser rx power high warning threshold : 0.7943 mW / -1.00 dBm
Physical interface: xe-0/0/46
Receiver signal average optical power : 0.9650 mW / -0.15 dBm
Laser rx power high warning : On
Laser rx power high warning threshold : 0.7943 mW / -1.00 dBm
Physical interface: xe-0/0/47
Receiver signal average optical power : 0.8618 mW / -0.65 dBm
Laser rx power high warning : On
Laser rx power high warning threshold : 0.7943 mW / -1.00 dBm

The output power on the QSFP+-40G-SR4 interfaces are within normal rage:
 
admin@qfx5100-48t-00# run show interfaces diagnostics optics xe-0/0/48:0 |match "Laser output power :|Lane"
Lane 0
Laser output power : 0.958 mW / -0.19 dBm
Lane 1
Laser output power : 1.013 mW / 0.06 dBm
Lane 2
Laser output power : 1.025 mW / 0.11 dBm
Lane 3
Laser output power : 0.952 mW / -0.21 dBm

QFX-QSFP-40G-SR4 Laser output threshold is [-7.6 dBm ~ 2.4 dBm] based on Interface Specifications for SFP, SFP+, and QSFP+ Transceivers for the QFX Series

SFP+-10G-SR Laser rx power threshold is [-9.9 dBm ~ -1.0 dBm]

This means when output power of the QFX-QSFP-40G-SR4 is between -1.0 and 2.4 which is within normal range, it will exceed the peer SFP+-10G-SR’s normal range.
Cause:

This is because the Tx/Rx power windows of 40G QSFP+-40G-SR4 and 10G SR/USR do not line up.

Solution:

It is recommended to use channelized QFX-QSFP-40G-ESR4 for 4 x 10G break-out to be connected with 10G SFPs, not QFX-QSFP-40G-SR4.

Notes:

  1. When you want to channelize and use 40G ports, you need to use QFX-QSFP-40G-ESR4.
  2. When you don't need channelization, use QFX-QSFP-40G-SR4.

Related Links

Comment on this article > Affected Products Browse the Knowledge Base for more articles related to these product categories. Select a category to begin.

Getting Up and Running with Junos

Getting Up and Running with Junos Security Alerts and Vulnerabilities Product Alerts and Software Release Notices Problem Report (PR) Search Tool EOL Notices and Bulletins JTAC User Guide Customer Care User Guide Pathfinder SRX High Availability Configurator SRX VPN Configurator Training Courses and Videos End User Licence Agreement Global Search