Ravenna AES67 Practical Manual page 6

terms like "backplane speed" or "non-blocking switch fabric" etc. if you expect a high load on your
switch.
2.1.1.4 "Green" is evil
While preserving energy is usually a good idea, it impedes proper operation of any low latency real-
time audio-over-IP technology. With the energy-saving function switched on, most switches will not
forward single incoming packets immediately, but will wait for a few more packets to be sent down a
specific link. This will result in an increased packet delay variation (PDV) which directly affects the
PTP operation (end nodes fail to settle into a stable sync condition or exhibit a large time jitter).
Therefore, for optimum network performance, all energy-saving functions on switches should be
disabled.
2.1.1.5 Cabling
This may sound like odd advice, but ensure that you are always using quality patch cables. The
required grade for GbE is Cat5e, but it doesn't hurt to use Cat6 or Cat7 cabling, especially if you need
longer runs close to the maximum allowed Ethernet cable length (~ 125 m). Special care needs to be
taken with mobile installations where cables often come on a drum for multiple uses: cable quality
will degrade over time as twisted pairs tend to slacken inside the cable. This may lead occasionally to
dropped packets despite signaling an otherwise proper link status.
2.1.2 IP addressing
Even if you are planning a small or medium-sized installation running on a single LAN, IP addressing
is required. In general, there are three methods to assign IP addresses (and every device, including
the switches, requires an IP address):
•
DHCP: an automatic IP address assignment which requires the presence of a DHCP server; in
most cases this can be one of the switches if a dedicated DHCP server is not present. While
this method is very convenient as you don't have to fiddle with address administration,
subnet and gateway configuration, the disadvantage is that the assigned IP addresses are not
immediately known (however, a device GUI will reveal its current IP address in most cases)
and that devices may not receive the same IP address again once repowered or reconnected
to the network.
•
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Zeroconf : an automatic IP address assignment which doesn't require a DHCP server.
Devices entering the network assign themselves an available IP address in the pre-defined
zeroconf IP address range
device network configuration in small LAN setups, it exhibits the same disadvantages as
DHCP (you will get different IP addresses each time), plus you can't even select the IP subnet
range.
•
Manual / static IP configuration: This method requires devices to be configured individually,
and IP addresses are assigned on an administrative basis. While this is quite a lot of work,
especially in larger environments, it provides full control on how subnets and devices are
configured. Since IP addresses remain unchanged after repowering or reconnecting to the
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https://en.wikipedia.org/wiki/Zero-configuration_networking
169.254.0.0/16.
While this is also a convenient method for
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AES67 Practical Guide