SIP on FTTH systems
cdel.firsthand.net
cdel at firsthand.net
Thu Feb 6 09:56:45 UTC 2014
Time for users to consider splitting L2 services from IP ?
Christian de Larrinaga
> On 6 Feb 2014, at 08:01, Mark Tinka <mark.tinka at seacom.mu> wrote:
>
> On Thursday, February 06, 2014 09:19:59 AM Måns Nilsson
> wrote:
>
>> Or, one could make sure everything has a globally unique
>> IP address and is using reasonably secured
>> communications. The downside is that one then can't
>> defend the existence of those empire-building
>> middleboxes. It is not the telco way, so is of course
>> unthinkable. Like anything beyond WAP was on cell phones
>> a decade ago.
>
> There are, typically, three topology models for modern FTTH
> (wireline, really) networks that a service provider could
> deploy:
>
> 1. SVLAN N:1 model
> 2. CVLAN 1:1 model
> 3. Hybrid of both
>
> The SVLAN (N:1) model is simple; just have a single VLAN for
> each service (VLAN 10 for Internet/Unicast, VLAN 20 for
> VoIP, VLAN 30 for IPTv/Multicast). This is simple and easy
> to scale, but if one is using relatively "dumb" AN's (like
> GPON's or MSAN's), it can be difficult to control how much
> bandwidth customers need, and how they can roam between
> services in the home (given CPE ties services to ports).
>
> The CVLAN (1:1) model is good for identifying services and
> bandwidth requirements on a per-customer basis. The main
> problem with this model is that Multicast traffic gets
> treated like Unicast, because each customer has a unique
> VLAN for themselves, and as such, the upstream PE router
> ends up having to replicate the same linear video stream as
> many times as there are customers down the line.
>
> The Hybrid model, where CVLAN's are used for all Unicast
> traffic (Internet, VoIP and VoD, typically), and a single
> SVLAN is used for all customers to handle Multicast traffic
> (so-called MVLAN). The challenge here is if you're the type
> of operator that likes to have a consistent set of address
> per VLAN, it can become a little tricky if your VoIP service
> is a walled-garden running on private IP space, given it
> shares the same VLAN as Internet and VoD which would
> normally run on public IP space.
>
> The N:1 SVLAN model is quite simple and scalable for
> wholesale FTTH services.
>
> There is product from some vendors, now, that is built with
> FTTH in mind. 1U, dense switches (Active-E) that support
> (reasonably) proper QoS and bandwidth management controls on
> customer- and core-facing ports, at Layer 2. So that offers
> you a lot more capability at the AN, and you can manage
> bandwidth as close to the customer as possible, unlike
> typical GPON deployments which may not have these features,
> leaving you to apply bandwidth policy at the PE router -
> much too far up the line.
>
> These new products can also support split horizons across
> bridge domains (which GPON's and DSLAM's do today), meaning
> that customers can use the same SVLAN's, but can only
> communicate via the upstream router (Layer 3), eliminating
> risk associated with Layer 2 visibility between customers
> connected to the same bridge domain.
>
> Cheers,
>
> Mark.
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