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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>List,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I wanted to get some views and experiences of the much
touted ‘IP DSLAM’. As far as I can tell, many of the DSLAMs on the
market right now are more Ethernet DSLAMS effectively bridging with a bit of fancy
snooping etc for multicast. I call an IP DSLAM a box that has encapsulates
subscriber traffic into IP packets on the trunk interface. Products on the
market include the Alcatel ISAM, Huawei MA5600, Lucent Stinger etc with their
relevant ‘BRAS/ IP Services’ module. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Up to now, I can’t find many examples of large
deployments of fully distributed BRAS within the DSLAM. In an IP world, surely
this is the realisation of a network engineer’s dream but few seem to
have implemented it. The industry seems divided on this. Some vendors believe the
Metro POP is as far out as you should push the BRAS.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’m looking for some real world telco/clec views
fro people who have either evaluated or implemented this entirely distributed
BRAS architecture to support single, double or triple play services. We are
still running PPPoE on subscriber CPE and though getting rid of PPP and L2TP
altogether in favor of a DHCP addressing mechanism is a sweet dream, it’s
a few years away at best. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>In my scenario, I’d be looking for the ‘BRAS
Card’ to be terminating PPP sessions and performing L2TP LAC
functionality. Next stage would be to remove L2TP and terminate PPP sessions at
the DSLAM allowing local routing, VPN’s, Voice breakout etc…, The
final Phase would be to wave goodbye to PPP and address all devices with DHCP
using an IP Helper on the BRAS card. (This PPP issue warrants a thread of its
own)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’d like to hear pro’s and cons, a few of mine
are listed below.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Pros:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<ol style='margin-top:0cm' start=1 type=1>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>IP Backhaul ( Easier to
diagnose IP than PPPoE, Easier and cheaper to create resilience and to load
balance over multiple links)<o:p></o:p></span></font></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Better abilty to schedule based
on IP CoS/ QoS requirements at first congestion point (middle mile)<o:p></o:p></span></font></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Potentially better network
availability vs huge centralized BRAS at POP ( less customers affected by
BRAS outage)<o:p></o:p></span></font></li>
</ol>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Cons: <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:54.0pt;text-indent:-36.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><span
style='mso-list:Ignore'>1.<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'>
</span></font></span></span></font><![endif]><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Complex address management<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:54.0pt;text-indent:-36.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><span
style='mso-list:Ignore'>2.<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'>
</span></font></span></span></font><![endif]><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>More devices in dynamic routing
domain<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Please let me know your views<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Vusi<o:p></o:p></span></font></p>
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