WISP Design: Using OSPF to build a transit fabric over unequal links
Defining the problem – unused capacity
One of the single greatest challenges if you have ever owned, operated or designed a WISP (Wireless Internet Service Provider) is using all of the available bandwidth across multiple PtP links in the network. It is very common for two towers to have multiple RF PtP (Point-to-Point) links between them and run at different speeds. It is not unusual to have a primary link that runs at near-gigabit speeds and a backup link that may range anywhere from 50 Mbps to a few hundred Mbps.
This provides a pretty clean HA routing architecture, but it leaves capacity in the network unused until there is a failure. One of the headaches WISP designers always face is how to manage and engineer traffic for sub-rate ethernet links – essentially links that can’t deliver as much throughput as the physical link to the router or switch. In the fiber world, this is pretty straightforward as two links between any two points can be the exact same speed and either be channeled together with LACP or rely on ECMP with OSPF or BGP.
However, in the WISP world, this becomes problematic, as the links are unequal and Continue reading
WISP Design: Using OSPF to build a transit fabric over unequal links
Defining the problem – unused capacity
One of the single greatest challenges if you have ever owned, operated or designed a WISP (Wireless Internet Service Provider) is using all of the available bandwidth across multiple PtP links in the network. It is very common for two towers to have multiple RF PtP (Point-to-Point) links between them and run at different speeds. It is not unusual to have a primary link that runs at near-gigabit speeds and a backup link that may range anywhere from 50 Mbps to a few hundred Mbps.
This provides a pretty clean HA routing architecture, but it leaves capacity in the network unused until there is a failure. One of the headaches WISP designers always face is how to manage and engineer traffic for sub-rate ethernet links – essentially links that can’t deliver as much throughput as the physical link to the router or switch. In the fiber world, this is pretty straightforward as two links between any two points can be the exact same speed and either be channeled together with LACP or rely on ECMP with OSPF or BGP.
However, in the WISP world, this becomes problematic, as the links are unequal and Continue reading
