Split chassis ons15454

Unanswered Question
Oct 28th, 2008

I currently have 2 (ons15454) chassis campus setup connected to DWDM network. The top chassis consists of OPT BST-E OPT-pre,32WSS, 32 DMX, OSCM, TCC2P,East & West. Bottom chassis has 4 MXPP-MR2.5, and TCC2P. I would like to split chassis i.e move all east down to bottom chassis and split MXPP_MR cards between chassis? Is this possible, what steps, and how far can chassis be from each other? I would like to put in seperate bldgs on campus for DR reasons. TIA

I have this problem too.
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drolemc Tue, 11/04/2008 - 07:01

If you are going replace or ONS 15454 Chassis Swap. It affects your services. All traffic that drops at the Network Element (NE) is affected for the duration of this procedure. Cisco highly recommends that you temporarily re-route any traffic that drops at the NE on other facilities before you start the procedure.

Below doc specifies the procedure for swap the Chassis on ONS 15454.

http://www.cisco.com/en/US/products/hw/optical/ps2006/products_tech_note09186a008069d06e.shtml#backinfo

ghares Tue, 11/18/2008 - 01:50

The answer to your question is YES you can split your chassis. The Express ports on your WSS is what will connect the East and West side of your equipment between the buildings. You can have up to 3db of loss on the express path interconnect. It is best if you remodel your network and make sure the additional loss on the express path is calculated into the new design.

RICHARD MASSELLE Thu, 12/11/2008 - 06:07

Thanks for your reply..I knew about using the express path, but didn't know how much loss to expect. We have multiple nodes in ring topology, with dual chassis at each node site.I notice that some chassis use express path and some don't. I am not sure why this is? Someone else installed chassis.

Tom Randstrom Thu, 12/11/2008 - 07:18

A node in your network may not have the express path cabled in order to reduce noise accumulation in the network.

"In a mesh ring network, the ONS 15454 requires a node configuration that prevents amplified spontaneous emission (ASE) accumulation and lasing. An anti-ASE node can be created by configuring a hub node or an OADM node with some modifications. No channels can travel through the express path, but they can be demultiplexed and dropped at the channel level on one side and added and multiplexed on the other side."

The use of this type of node is determined by the Cisco TransportPlanner design software.

RICHARD MASSELLE Thu, 12/11/2008 - 07:29

Thanks for the reply. I had heard of anti-ASE nodes , but did not neccessairly understand application. I will do some research on this. That does however; put a crimp in the idea of splitting chassis and installing an East - West node in different locations across campsu.

viyuan700 Thu, 12/11/2008 - 11:04

"I currently have 2 (ons15454) chassis campus setup connected to DWDM network. The top chassis consists of OPT BST-E OPT-pre,32WSS, 32 DMX, OSCM, TCC2P,East & West. Bottom chassis has 4 MXPP-MR2.5, and TCC2P. I would like to split chassis i.e move all east down to bottom chassis and split MXPP_MR cards between chassis? Is this possible, what steps, and how far can chassis be from each other? I would like to put in seperate bldgs on campus for DR reasons. TIA"

In your 2 chassis, one is used as DWDM (which has OPT, post pre amplifier, WSS ROADM, DMX demultiplexer) and second one which has MXPP card is for muxponder from where u r adding ur client signal. Your client signal goes to east and west both direction (all this is done by the back plane of DWDM chassis) , if your east fiber goes down u r still connected through west. So this design is capable of one side link failure. But if something happens to your 2 ONS in your building then you have to wait until they are up.

You have several channel coming but all of them need not to be dropped at that site so there is no need of dropping that signal. So it is passed to other side without going through any muxponder, it is just passed to other side mux and amplifier. These paths are called express path. If any of the express path is traveled too many amplifiers without dropping then it is possible that that signal will have ASE (amplified spontaneous emission). It is required to regenrate that signal even though it is not to be dropped on that side.

So express path is not going to help you. Your design has link failure redundancy and you want equipment failure redundancy. So that if something happens to equipment in one building other one is safe. All east side stuff in one and west side stuff in another and keep them in different building.

As per my knowledge you cannot do that, as the signal from muxponder after it is copied to east and west and it is done by the back plane. Similarly your one client signal comes from east and west and is changed to one by backplane. That's how you don't lose your signal if there is link failure on one side east or west. You connect multiple chassis to get more wavelength but they are on the same rack or nearby rack (something like stacking). I think you need 2 more ONS to get the DR you are thinking of.

Hope the explanation will help you in your decision process.

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