[AusNOG] Looks like the NBN will be a PON variant for sure...

Matthew Moyle-Croft mmc at internode.com.au
Wed Apr 29 15:01:29 EST 2009

On 29/04/2009, at 9:42 AM, Mark Smith wrote:
> Look up "IPoE" in Google (as silly as the acronym is), all those
> problems have or are being solved (e.g. cable networks use DHCP, and  
> all
> the Ericsson DSLAMs that a lot of ISPs have are (and have been for a
> long time) "IPoE" capable)). Cisco's ISG product can apparently turn
> DHCP leases into RADIUS accounting records for example.

You still need the same boxes (eg.  Cisco10ks, ASRs, Juniper E series,  
Redback etc). to do this.   The number of "sessions" they do when  
running in this mode doesn't increase.   So, ultimately you've really  
just swapped one problem for another as far as I can see.

(Most of these platforms can run in a "smart" mode where you send it  
frames (PPPoE, q-in-q stacked customer-per-vlan, fixed IP stuff and  
then they 'figure it out" and turn it into a "service").

If you run a flat vlan, then you need to do work to ensure customers  
can't compromise the service via injecting their own frames (eg.  
pretending to be a DHCP server).  Certainly a lot of the DSLAM and  
other equipment vendors can do this, but it's another thing you need  
to do.

> In a "native", not wholesale ADSL environment, the 8 byte per-packet
> overhead and BRAS processing load, MTU issues and hair-pinning of  
> encapsulated traffic are very expensive, when you consider that the  
> only
> real purpose of converting a multi-access medium like Ethernet into a
> point-to-point virtual link is to be able to authenticate the user. If
> you already know where they live (and DSLAMS can insert that circuit- 
> id
> in DHCP requests), why do you care what username / password they use?

Username/Password is good for ensuring it's really the customer using  

I'm not against ditching PPP but it's a well understood thing and easy  
to do in a wholesale model as NBN will be.

However, a per-user VLAN might be nice too if the aggregation can be  
sorted out (imagine BIG vlan rewrite switches!).

Matthew Moyle-Croft
Networks, Internode/Agile
Level 5, 162 Grenfell Street, Adelaide, SA 5000 Australia
Email: mmc at internode.com.au    Web: http://www.on.net
Direct: +61-8-8228-2909		     Mobile: +61-419-900-366
Reception: +61-8-8228-2999        Fax: +61-8-8235-6909

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