[j-nsp] questions regarding submarine cables

[Tom Storey]

The Pipe International blog is excellent, I followed it from start to
finish while it was happening. It gives a real insight that has probably
never been given before about the construction of a submarine cable, and
some of the operational aspects (at least not on a free for all public
blog).

Dont forget to read the comments section of each article, as additional
questions and answers can be found there!

Tom

On 12 December 2011 03:02, Mark Tinka <mtinka at globaltransit.net> wrote:

> On Monday, December 12, 2011 06:54:14 AM Martin T wrote:
>
> > This isn't directly related with Juniper, but hopefully
> > not totally off-topic as well :) At least here might be
> > some industry insiders, who have some experience with
> > submarine cables.
>
> It's operational in a way that affects the Internet, so I'm
> happy :-).
>
> > 1) According to engineer in this video:
> > http://vimeo.com/29975179 ..modern submarine cables are
> > often built as self-healing rings. For example "FLAG
> > Atlantic (FA-1)" between USA and Europe seen here:
> > http://www.cablemap.info/ is a good example. How does
> > such self-healing ring works?
>
> In essence, it's not that different from SDH or SONET rings
> built on land.
>
> See here:
>
>        http://en.wikipedia.org/wiki/EAC-C2C
>
>
> However, it is also feasible that some cable operators
> consider options for building 2x or more linear paths, as
> opposed to ring topologies (ring topologies do have their
> own sets of challenges, e.g., choosing the best route,
> guarantees on latency, management, e.t.c.; which is not to
> say that linear topologies do not bring with them their own
> unique set of constraints - it's a balancing act).
>
> > Am I correct, that in case
> > both cables are healthy, only one of two is utilized
> > with traffic?
>
> Cable operators are unlike IP operators. They don't normally
> load balance traffic across all available physical media.
>
> They could use the other part of the cable as a "Protect"
> circuit, i.e., if you buy a service from the cable operator
> and request for protection, the protection will be enabled
> on the other part of the ring.
>
> Some operators run as many as 3x rings and designate that as
> "primary", "secondary" and "tertiary".
>
> > Who provides equipment for such setups(I
> > guess Alcate-Lucent is one of the vendors)?
>
> Key submarine equipment (SLTE) vendors are:
>
>        o ALU.
>        o Fujistu.
>        o NEC
>        o Tyco.
>
>
> Some of the terrestrial players are now looking to enter
> this space, e.g., Huawei, Infinera, Nortel, e.t.c.
>
> > In addition,
> > how long it will take such switch-over to occur? Are we
> > talking about couple of milliseconds or few seconds?
>
> Cable operators offer 50ms failover for pre-provisioned
> protect circuits. Typical electrical hand-offs to customers
> are SDH or SONET, although Ethernet is now commonplace. I've
> dealt with SDH and Ethernet only.
>
> However, I know some cable operators are considering
> GMPLS/ASON which does provide protection, but may not be as
> quick as 50ms. GMPLS, for example, uses an IP control
> comprising:
>
>        o OSPF-TE or ISIS-TE for routing.
>        o RSVP-TE or CR-LDP for signaling.
>        o LMP for link management.
>
> Of course, what we normally do is rather than buy a service
> + protect circuit from the same cable operator, we buy 2x
> service circuits from different operators so we can:
>
>        a) Have both circuits active at the same time.
>        b) Reduce risk by using different providers.
>
> > 2) In case cable has multipoint landings(for example
> > "GLO1", which has 15 landings in west coast of Africa
> > and Europe) then submarine branching units should be in
> > use. How this branching works? Are some waves(CWDM)
> > inside the cables switched towards the landing and other
> > continue via submarine cable? Because as I understand,
> > on a wave level, we are still talking about point to
> > point connections(?). In addition, are those branching
> > units under the water or are they on small islands, oil
> > platforms etc if possible?
>
> That is what is called an OADM-BU. You may take a look here:
>
> http://www.nec.co.jp/techrep/en/journal/g10/n01/100104-71.html
>
> http://blog.pipeinternational.com/index.php?option=com_myblog&show=The-
> OADM-BU.html&Itemid=53
>
> Hope this helps.
>
> Cheers,
>
> Mark.
>
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