Wholesale broadband fault isolation
A wholesale broadband fault can sit in several places, and most wasted time comes from escalating to the wrong party. A clear order of checks, and the evidence that proves each one, resolves faults faster and keeps the right people accountable.
Follow the session, in order
When a subscriber cannot get online, the fault is in one of a small number of stages, and they are best checked in the order the session is built. First, is the access line up, so the line to the premises is working and the session is reaching the handover at all? Second, is the L2TP session establishing to your network? Third, does authentication succeed against your RADIUS? Fourth, is the subscriber getting an address? Fifth, is traffic actually reaching the internet and back?
Each stage has a different owner. The access line belongs to the access network, the session and everything after it belongs to you as the ISP. Working through them in order tells you which party to involve, and stops you escalating an authentication problem to the access network or a line fault to your own engineers.
Gather the evidence before you escalate
Every escalation is faster when it carries proof. Before handing a fault to the access network, establish that the session is not reaching the handover. Before blaming authentication, show the Access-Request arriving and the reply that came back. Before calling it an addressing fault, confirm whether an address was assigned. The subscriber session on your broadband edge holds most of this, which is one reason to run a platform that exposes session state clearly.
Netavo hands broadband sessions from national and regional UK access networks to your own network over L2TP, where your platform authenticates and addresses them, so the boundary between the access network's responsibility and yours is clean. For how sessions are terminated and what state is visible, see the wholesale broadband guide and the Netavo BNG engineering library.
Common questions
Where does the access network's responsibility end?
At the handover. The access network carries the line and the session to the handover point; from there the ISP owns session establishment, authentication, addressing and onward reachability.
A subscriber authenticates but has no internet. Where do I look?
Past authentication: check that an address was assigned and that routing and any carrier NAT are working. Authentication succeeding rules out the access line and the credentials.
What evidence should an escalation carry?
Proof of which stage failed: the session reaching or not reaching the handover, the RADIUS request and reply, and whether an address was assigned. Evidence routes the fault to the right owner.
Running a wholesale broadband service?
Tell us how you terminate subscribers and where faults are costing you time, and an engineer will talk through the handover and the tooling.
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