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31 janvier 2012 2 31 /01 /janvier /2012 09:00

The aim of this post is to provide the detailed procedure for upgrading the Switch Control Boards (SCB) of an MX960 chassis in order to overcome some limitations of the old SCB that are :


-          Unable to use the full load of the 16x10GE card and to keep fabric redundancy

-          Bandwidth limitation of a chassis with mix cards : DPCE and MPC

-          No support of the next generation of MPC : MPC3


This procedure includes 2 migration cases : with or without traffic. Although the procedure “with traffic” avoids, as muck as possible, traffic impact, the last step of this procedure implies a short outage of traffic.


1/ E-SCB presentation


The New SCB called E-SCB for Enhanced SCB is supported since the 11.4 Junos release. This new fabric card is based on a new fabric chip called XF chip. Each E-SCB hosts 2 XF chips, each of them is called a PLANE.


Therefore, with 3 SCB into a chassis we have 6 planes (2 per SCB card). This new XF chip allows to “over-clock” the High Speed Link (HSL) of the MPC cards. Indeed, with the old SCBs the "links" between the MPC and the Fabric were limited to 5Gbits/s. Now, with the E-SCB we can used these same links at 10Gbits/s.


The 6 planes in “active” state is not mandatory anymore to use the “full load” (12 ports linerate). So 4 planes will be in “active” state and 2 in “spare” state in order to cope with the full bandwidth load in case of a plane or SCB failure.




2/ Requirements


A couple of steps are optional and depend on whether you want to keep traffic or not during the SCB migration. The requirement in all cases is :


-          The node must be upgraded in release 11.4R1 or above.


The 2 other requirements if you want to carry out the migration “in-traffic” are :


-          Activate GRES (Graceful Routing Engine Switchover) :


set chassis redundancy graceful-switchover


-          Activate NSR (Non Stop Routing)


set routing-options nonstop-routing


N.B. : check that each feature you implement does support NSR

N.B.++: The optional steps/commands are highlighted in yellow


3/ The procedure


The following PDF provides the detail of each step :  The detailled procedure




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