[AusNOG] Equipment upgrade path

[Ahad Aboss]

Hi Paul,

Hope you are well.

Based on the information you’ve shared below are some suggestions that does
not take high availability into account.

Given that you are running a small ISP, my suggestion is to continue using
the ASR1K for Telstra & AAPT ethernet services until you get close to
maxing out the backplane and separate the L2TP or IPOE sessions into a
separate PE. You can always upgrade the PE to ASR1004/1006/1013 as your
customer base grows.

The ASR1K enables you to shape Telstra / AAPT customer circuits at the
headend or per vlan sub-interfaces. It also comes with a lot of features
that a Nexus 9K in L3 setup cannot support/perform as well as the ASR1K.

I am assuming your aggregate traffic handled by ASR1001 for Telstra / AAPT
is less than 4-5Gbps though most ISPs oversubscribe these services 4:1 at
the aggregation point/headend.

Given the above, a key starting point is to separate your residential (DSL)
and corporate (ethernet / fibre) customers into at least 2 pairs of PE
routers – this is a good practice from the HA and operations point of view.

The Nexus 9K is a nice ToR & leaf switch but in a server facing environment
where its often used as a L3 gateway. It supports QoS, BGP and even NAT
with limitations 😊

I’ll be more than happy to answer any specific questions in terms of the
design or implementation for these services as I’ve deployed it in
small-scale and large-scale ISP environments.

Have a great weekend.

Ahad

On Mon, Nov 19, 2018 at 10:47 AM paul hollanton <paulhollanton at gmail.com>
wrote:

> Good morning list,
>
> I hope you all have had a good weekend.
>
> I’m returning to the ISP industry after a longer than expected stint in
> the corporate space and was hoping to get some pointers on some
> infrastructure upgrade options which I’m having to consider.
>
>
>
> I work for a small-ish ISP that offers some (but not a lot) DSL/NBN
> services and a bunch of  TLS such as Telstra’s Ethernet Access and AAPT
> e-lan etc. with the odd mpls layer3 vpn too.
>
>
>
> We’ve been using Cisco ASR1001 routers for L2TP (DSL/NBN) termination as
> well as sub-interfaces for the TLS services with the headend trunks from
> the suppliers terminated on a switch that’s providing a layer2 only
> function.
>
>
>
> Rather than upgrading and continuing to terminate all TLS services on the
> ASR, I thinking of purchasing a layer 3 switch such as the Cisco Nexus
> 9236C or similar and terminating the TLS services on this as well as the
> supplier trunks – the 100Gb port functionality should allow us to have the
> device(s) in operation for some time before needing to upgrade.
>
>
>
> The documentation on the units state that they support mpls and BGP which
> is nice, but if anything too heavy is required for customers with special
> requirements , perhaps we’d leave that to the ASR – which will also
> continue to perform any L2TP and NAT requirements.  To be honest, none of
> the documentation on the Cisco layer 3 switches suggest they are suited to
> what I have in mind, which brings me to my main question...
>
>
> Is whether the introduction of a layer3 switch for this function is a good
> idea, or should we continue to use ASR’s for the job?  My other concern
> is will the Nexus be able (or is suitable) to do the traffic shaping that
> is required for the Telstra Ethernet Access services (which is important
> that it’s done exactly right) and other QoS functions such as voice
> prioritisation.
>
>
>
> If there’s a better design or more suitable equipment I should consider,
> please let me know.  I’d prefer to stay with Cisco as the vendor, primarily
> as the migration path will (should) be simpler and I have reasonably good
> experience with them over the years.
>
>
>
> Thanks,
>
> Paul
>
>
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