[VoiceOps] Inbound Redundancy

Alex Balashov abalashov at evaristesys.com
Mon Aug 24 10:02:12 EDT 2009

Another thing to consider is that in the BGP world, the IP block(s) 
announced by the customer are actually "owned" by the customer, in an 
administrative and a technical sense.  This is true whether they are 
subnets of a provider's aggregate, or provider-independent blocks 
obtained directly by the customer through a RIR like ARIN.

The ISPs really do just provide the transit.  You can announce whatever 
blocks you want to them (that they let you/don't filter), and they can 
announce those blocks on behalf of their subtended networks (customers).

PSTN numbers don't work that way, conceptually.   You may, as a 
customer, "own" the numbers in some legally significant way, but as 
implemented in the underlying technology, they are homed (or ported) to 
a carrier switch. That's just where they go, and that's what makes them 

When it comes to multi-provider redundancy, I think the eventual 
solution - if there's any interest and business case for one - will be 
less to hair-trigger NPAC subscriptions to another OCN/LRN, protection 
switch-style, and more the use of some sort of "logical" number or 
identifier that is a wrapper for the underlying numbers that are still 
statically assigned to a particular carrier.  Sort of like a hunt group 
or find-me-follow-me functionality, but on a lower level of abstraction.  :)

-- Alex

Alex Balashov - Principal
Evariste Systems
Web     : http://www.evaristesys.com/
Tel     : (+1) (678) 954-0670
Direct  : (+1) (678) 954-0671

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