Number of hops
Info
The maximum number of hops is dependant on the network speed.
- A 100Mbit network allows for max. 7 hops before it reaches the 2ms presentation time offset.
- A 1Gbit network allows for max. 14 hops before it reaches the 2ms presentation time offset.
A Milan AVB network is fully time-aware, meaning switches account for the worst-case residency time of a packet. Unlike other audio network protocols, Milan ensures that the required transmission time can be determined before a packet is sent. By configuring the Stream PTO in the Talker, it is possible to verify in advance whether a deadline can be met.
Each transition a packet makes through a switch is known as a hop.
As a rule of thumb, the worst-case residency time for a packet in a switch is approximately 140µs on a 1Gbit/s network and 280µs on a 100Mbit/s network.
Milan specifies a latency limit of 2ms for guaranteed packet delivery. This allows for a maximum of 14 hops on a 1Gbit/s network and 7 hops on a 100Mbit/s network. As shown in Fig. 1 and Fig. 2, fewer hops result in lower latency within a Milan network.
| 100Mbit/s | 1Gbit/s | |
|---|---|---|
| Latency per hop | 280us | 140us |
| Max. number of hops | 7 | 14 |
Max. number of hops in a 100Mbit/s network
Max. number of hops in a 1Gbit/s network
