working with SNCP rings

Unanswered Question
Oct 11th, 2009

Hi,

im setting up an SNCP ring on the 15454E running rel 9.0

although SNCP is the default state for the ONS, I need some help from the experts out there for things i have not yet figured out.

1. SNCP is path based protection and doesnt use the K bytes as far as i can understand. For the SDH DCC terminations configuration when setting up an SNCP ring, is RS-DCC or MS-DCC to be used ?

2. Are protection groups required to be defined for SNCP or is this just used for linear setups ?

3. other than installing the cards, connecting the fibres, and configuring the DCC and circuit appropriately is there anything else really required for setup ?

4. sncp ring gives you protection for the ring between ONS chassis like so:

STM-4---ONS<===ring===>ONS---STM-4

The drop to the customer in this case is a single tx/rx fibre pair.

If I want to setup a working/protect from ONS to customer, as far as i can understand this requires APS which uses the K bytes. Is an SNCP ring suitable here, or due we have to use MS-SPRing. If so do we extend the MS-SRPing to the customer device, so it receives the K bytes for APS ?

thanks much

Mark

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Tom Randstrom Sun, 10/11/2009 - 08:40

1. SNCP is path based protection and doesnt use the K bytes as far as i can understand. For the SDH DCC terminations configuration when setting up an SNCP ring, is RS-DCC or MS-DCC to be used ?

"Set-up the RS-DCC per the instructions (link below) to have visibility and access to remote node."

<http://www.cisco.com/en/US/docs/optical/15000r9_0/15454/sdh/procedure/guide/454e90_dlp3.html#wpxref39948>

2. Are protection groups required to be defined for SNCP or is this just used for linear setups?

"Protection groups are used for 1+1 and 1:N card protection."

3. other than installing the cards, connecting the fibres, and configuring the DCC and circuit appropriately is there anything else really required for setup ?

"Set-up node timing."

4. sncp ring gives you protection for the ring between ONS chassis like so:

STM-4---ONS<===ring===>ONS---STM-4

The drop to the customer in this case is a single tx/rx fibre pair.

If I want to setup a working/protect from ONS to customer, as far as i can understand this requires APS which uses the K bytes. Is an SNCP ring suitable here, or due we have to use MS-SPRing. If so do we extend the MS-SRPing to the customer device, so it receives the K bytes for APS ?

"If the customer's equipment supports 1+1 linear protection scheme, then you can set-up a 15454 protection group through the "drop" interfaces (to the customer). The 15454 can support a mix of protection schemes from the same node/chassis."

STM-4==(1+1)==ONS<===RING===>ONS==1+1==STM-4(1+1)

Hope this helps!

viyuan700 Sun, 10/11/2009 - 17:47

Hi Mark ,

You have got answer for first 3 questions from Tom, for last one i have something more to say.

"If I want to setup a working/protect from ONS to customer, as far as i can understand this requires APS which uses the K bytes. Is an SNCP ring suitable"

You dont need APS or K byte to drop customer if it is 1+1 protection. But you need APS and K byte if you are providing 1:1 protection.

You can do the following whatever is your setup

1.You can include the customer in the same STM 4 ring if you are providing them STM equipment.

2. You can extend STM 1 ring for customer using 2 STM 1 port in your STM 4 ring. Here instead of providing protection by APS provide 1+1 SNCP protection. Here you can form ring if fiber is entering to your customer from 2 different places (2 cables). If the fiber is linear (means it enters through only one cable) then you will use 4 fibers to form a ring. Protection time is faster and simpler in SNCP (1+1) then 1:1 protection.

MS-SPRing is complicated and have seen mostly on STM-16 kind of capacity and for a specific kind of traffic pattern. Maybe you dont need that in your network.

Hope it makes sense.

Mark Pace Balzan Sun, 10/11/2009 - 23:03

hi,

thanks for replies. not too clear on the protected link to customer equipment however.

one option to provide working and protect links to customer equipment is to configure 1+1 protection not APS ? For this i'd simply configure a card protection group on the ONS for the STM-1 ports going to the customer ?

im also looking at http://www.cisco.com/en/US/tech/tk482/tk607/technologies_tech_note09186a0080094c54.shtml which mentions APS 1+1 so Im getting confused. In the case of this type of setup what config is required on the ONS which is the ADM ?

I have really not found alot of info about this particular topic, would be grateful if someone recommends some links. ive already got two books from ciscopress but they dont tackle these options in detail.

thanks

Mark

viyuan700 Mon, 10/12/2009 - 06:27

"I m getting confused. In the case of this type of setup what config is required on the ONS which is the ADM ?"

I gotis what is creating the confusion here, whatever i said is true if you connect yourONS to another ONS or SONEt box. There you dont need K byte for 1+1 protection.

As same siganl is copied in both direction and receiver selects the signal. If there is LOS or Degradation it switches to the other siganl without any interaction with the source whereas you need that K byte if it is 1:1 protection.

But here case is different you are connecting your SONET ADM directly to a POS interfacein the router.

They have taken the 1+1 switching but added some more flavor to it.

Here both POS interface gets the copy of signal but ONLY one interface is up and other is down so the router dont try to form adjacency with the other router. If both interface are up both will try to form adjacency whereas the ADM takes only 1 siganl and ignores other. So the routing protocol will be working on something which is not there.

See this link will get more idea about it

http://www.cisco.com/en/US/tech/tk482/tk607/technologies_white_paper09186a0080094baa.shtml

Tom Randstrom Mon, 10/12/2009 - 06:30

Sorry for the confusion.

1+1 APS is what we are referring to. The 15454 supports both unidirectional and bidirectional 1+1 APS (bidirectional is preferred).

Optical Card Protection 15454

<http://www.cisco.com/en/US/docs/optical/15000r9_0/15454/sonet/reference/guide/454a90_cardprotection.html#wp198892>

http://www.cisco.com/en/US/docs/optical/15000r9_0/15454/sonet/procedure/guide/454a90_dlp0.html#wpxref33082>

Select Revertive (default time) & Bidirectional switching

Mark Pace Balzan Mon, 10/12/2009 - 23:00

Hi All

thanks alot for your help. now I think it clear :-)

1 last question in (iii) below

So in summary to ensure we are putting all the items together:

FOR SNCP ring between ONS boxes we dont need K bytes since traffic is replicated and switch is done based on LOS or degradation. Also we dont need to define protection groups.

For a link from ONS to customer, we then setup one of:

i. unprotected link from ONS to customer

ii. provide working and protect links to a customer location using ADM in customer building, and including this ADM in SNCP ring (or sub-ring) like we have said before:

STM-4==(1+1 SNCP)==ONS<===SNCP RING===>ONS==(1+1 SNCP)==STM-4

iii. When connecting working and protect links to a customer router, on the ONS ADM we connect two links to the customer router. Here we use 1+1 as well as K bytes for the router to select the link to use. For this do I understand correctly that the configuration on the ONS for link to customer is 1+1 protect group ? Anything else required on the ONS ? Of course the router would be configured as per APS document for the 12k. For this we get

STM-4==(1+1 Protect group)==ONS<===SNCP RING===>ONS==(1+1 Protect group)==STM-4

thanks

Mark

viyuan700 Tue, 10/13/2009 - 11:02

When connecting working and protect links to a customer router, on the ONS ADM we connect two links to the customer router. Here we use 1+1 as well as K bytes for the router to select the link to use. For this do I understand correctly that the configuration on the ONS for link to customer is 1+1 protect group ? Anything else required on the ONS ? Of course the router would be configured as per APS document for the 12k. For this we get

Yes the your configuration here is correct. 1+1 card protection is what you need in ONS (Not SNCP, when we connect more than one customer then we use SNCP ring) and i think Tom have already gave you a link.

I totally understood in different way.

Most of the confusion occurred because of the subject of the message which says SNCP but you are talking about 1+1 card protection.

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