Syslog to Telegram
Introduction
From time to time, I wish I could be made aware of failures earlier. There are two events, in particular, that I am interested to know about very quickly, as they may impact service at AS8298:
- Open Shortest Path First (OSPF) adjacency removals. OSPF is a link-state protocol and it knows when a physical link goes down, that the peer (neighbor) is no longer reachable. It can then recompute paths to other routers fairly quickly. But if the link stays up but connectivity is interrupted, for example because there is a switch in the path, it can take a relatively long time to detect.
- Bidirectional Forwarding Detection (BFD) session timeouts. BFD sets up a rapid (for example every 50ms or 20Hz) of a unidirectional UDP stream between two hosts. If a number of packets (for example 40 packets or 2 seconds) are not received, a link can be assumed to be dead.
Notably, BIRD, as many other vendors do, can combine the two. At IPng, each OSPF adjacency is protected by BFD. What happens is that once an OSPF enabled link comes up, OSPF Hello packets will be periodically transmitted (with a period called called a Hello Timer Continue reading