Anyone tunneling PDH/SDH inside MPLS?

Discussion in 'Networking, Telephony & Internet' started by yanman, Aug 9, 2013.

  1. yanman

    yanman Member

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    I'd like to find out if many orgs are using any sort of packetised tunneling of circuit-switched networks i.e. PDH and SDH.

    I've read about various technologies that apparently enable it, but the real killer-solution of GMPLS/MPLS-TP seems to be still in development with the IETF :/
     
  2. FiShy

    FiShy Member

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    I have one question.... why?
     
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    yanman

    yanman Member

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    Mostly because supporting the dedicated TDM equipment is a PITA. Lack of vendor options, high cost of management software, fewer and fewer people using it hence lack of skill-sets or the desire to acquire them.

    I can understand carriers might be reluctant since they have the install-base and customers still buying TDM circuits, but I'm talking for us who purely use it to service end-connections of 2Mbps and less.

    Just discoverd these fantastic looking devices.. certainly needs more research!
    http://www.juniper.net/us/en/local/pdf/datasheets/1000139-en.pdf
     
  4. FiShy

    FiShy Member

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    This is why i find it odd i guess as in my space its normally building new mpls based stuff on existing SDH networks.
     
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    yanman

    yanman Member

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    I'm certainly seeing more on building MPLS over SDH than visa versa. Is it because in the large carrier space it's more economical? And is that economy only for existing install-base or is it really more economical if you're talking from-scratch?

    It'll be interesting to see what changes when GMPLS and MPLS-TP are ratified and vendors start offering it.
     
  6. FiShy

    FiShy Member

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    Established carriers never build a network from scratch. Its always a evolution of existing infrastructure (towers/fibre/etc) and the two big carriers here have had established SDH networks (Telstra having a PDH one before that) built before MPLS became the current trend. Most have done a Ethernet over SDH to provide one deliver type end to end and then used a mpls core to punt it around.
     
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    yanman

    yanman Member

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    Yeh of course, it was purely an academic question. We're in the same boat.. although probably our big shifts have been large projects done over the span of several years.. like our migration from PDH to SDH multiplexers, and from TDM to IP/TDM hybrid radios.

    Those CTP devices look interesting though :)
     
  8. cvidler

    cvidler Member

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    I've only worked at two places in the country that tunnel circuit traffic over a IP (or ATM) network.

    One's a telco, the other is a BIG gov with lots of legacy and proprietary gear.

    I'm sure the other telcos would do so as well.


    It's not something you'd find in many places, they'd have to be big, and have legacy requirements. Anything built these days in the age of VoIP and UC do it all over IP.
     
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    yanman

    yanman Member

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    It's certainly not mainstream, but anyone running SCADA will most likely have a lot of legacy TDM connections.
     
  10. FiShy

    FiShy Member

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    One of our customers has large amount SCADA and the new MPLS stuff that was built for them was built to completly ignore the SCADA and leave it as a different network.. i.e too hard basket :)


    I agree the CTP stuff looks nice and thats the kind of kit juinper are normally good at.
     
  11. Heywood

    Heywood Member

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    A customer I worked with was performing a network migration from PDH to MPLS in part because the PDH gear was hitting EOL, it had limited instrumentation and didn't have service flexability for what they needed for future business. There were a couple of phases of transition/migration for services scheduled, it wasn't one size fits all but below was the general idea:

    1) Some of the P-MUXes actually had 100FX uplinks rather than the more expected E2/E3 transmission interfaces so it was possible to just transparently carry these services using an ethernet VLL over the MPLS network.

    2) In some cases the business case enabled the transformation/replacement of end equipment to native IP rather than E1/EIA-232 interfaces could occur (in some cases it was installing a new WAN card or this was a completely new site being built and not using legacy kit) services could then be either a VPLS or L3 VPN, or VLL if it was point-to-point.

    3) In some cases, legacy TDM transport was still needed (e.g. during network deployment some sites would take some time to become MPLS enabled so PWE3 service constructs were used to provide circuit emulation over the packet network) with the eventual intention to head towards #2

    Mobile network operators in particular have been using TDM over MPLS for legacy base stations for quite some time, if you search for cell site backhaul, you will find more vendors and products available than just Juniper's CTP platform e.g. I'm quite partial to the 7705 SAR family but then I used to work for the company that made them, so perhaps I'm biased.

    SDH over MPLS is possible but it may make more sense to remove the use of SDH and transport the native with an MPLS capable demarcation box, use the same access fibre then SDH gear would have used but use it to connect the demarc to the aggregation network. Or maybe MPLS isn't the right answer here at all and perhaps a xWDM solution or something else may be more appropriate.
     
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    yanman

    yanman Member

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    Thanks Heywood there's some great info to consider there.

    I'm glad to hear you're happy with the SAR gear - I also came across the 77xx SAR gear the other day searching for support for G.703. Unfortunately the Juniper CPT gear doesn't support it, yet this is one of our most commonly used circuits (protection). I'd say it'll stay that way until 61850 gets more traction. Our P-MUX's are EOL and also EOS so they'll be up for replacement.

    We are slowly progressing with the odd move to IP/Ethernet native devices but so far it's just little pilots here and there.

    I'd love to see any details that you're allowed to share on the project.
     
  13. Heywood

    Heywood Member

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    Just a heads up to those reading the thread and curious - I replied to yanman in a PM which basicly stated that there are some organisations which appear to be in the same industry sector he's in already using the platform I mentioned and an offer to introduce him to someone who may be able to provide reference information.
     
  14. CQGLHyperion

    CQGLHyperion Member

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    Good to read up on things like this.

    The company I work for is full of legacy equipment. PDH, SDH, ATM etc.

    Part of our network is moving to WDM which will transport some SDH but more as to allow for a MPLS replacement for the ATM network.

    Unfortunatley, our fibre is some of the oldest in the country, and DWM would struggle and be too costly with the amount of sites we have. Hence why we are going to just build MPLS with EoSDH. Sections that have new fibre will just have the MPLS directly onto its own.

    But I agree that SCADA is holding out network back as well. Mind you the older PDH gear is still running great and managed on some old NT based systems, that still work better then the new platforms some vendors try to sell at rediculous pricing!
     

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