[AusNOG] PPC-1 Experience?

[Lincoln Dale]

On 21/09/2010, at 8:41 AM, Skeeve Stevens wrote:

> Depends on how you are buying access to it.

you're asserting that latency of a cable system is dependent on how you buy access to it?
i must say, i've never heard that one before!

i think what you're stating is that since PPC-1 does not go to mainland USA then the latency between Aus/USA depends on the other cable systems chosen.  well, i think that goes without saying......


>> Was wondering, does anyone here have some numbers for the latency of
>> US transit across PPC-1?

per <http://www.pipeinternational.com/index.php?option=com_content&view=article&id=5&Itemid=45>, PPC-1 cable distance is "approximately 6900km".
i'd imagine that includes quite a few spurs so actual distance is likely hundreds of km less than that.  lets call it 6500km for example.  that gets you Sydney to Guam.

from Guam you have many choices in how you then get to mainland USA.  likely the shortest path would be Guam to Japan to US West Coast.

as the crow flies, Guam to Tokyo is 2507km, Tokyo to SJC is 8353km.  lets add on 15% as cables don't fly in a straight line and distance is 12489km + that ~6500km or close enough to 19,000km.
speed of light in glass is such that you can go approximately 1000km in 5msec, so 19,000km equates to ~95msec without any O-E-O overhead or routers/switches which may introduce some negligible additional latency.


i guess you want to see this compared to SCC?
based on the cable distances shown on the SCC website, Sydney / SJC would be 14,313km (best case) - with common cases likely being 14,777km or 15,510km.
lets go with the lowest.  14,313km equates to ~71.56msec one way.


>> 
>> I was in a discussion about it and the question came up about the path
>> it takes via Guam.
>> 
>> I realise Guam is a bit of a hub for these cables of course.
>> 
>> Part of the question was wondering if US transit via PPC-1 to Guam was
>> then via Japan or if it could go direct to the US from Guam.

it can go wherever there are cable systems.

<http://www.telegeography.com/product-info/map_cable/index.php> is a nice poster that shows you visually many of the options.
i believe the shortest distance Guam to West Coast US likely goes via Japan.


>> 
>> which then leads into the question of protection. SCC is said to be
>> protected. Is that where there are multiple paths or are they talking
>> about diversity at the landing points? Is PPC-1 "protected"?

diagrams tell the story.
SCC: see <http://www.southerncrosscables.com/public/Network/default.cfm>
PPC: i don't believe there is any diversity.

if there is a cable break on PPC-1 then i believe you'll lose service.
on SCC technically there could be a single failure and one would not lose service.  provided you have purchased diversity.


cheers,

lincoln.