RAD Data comm TDMoIP Gateway IPmux-16 - Manual (Page 19)

IPmux-16 Installation and Operation Manual Chapter 1 Introduction
Functional Description 1-11
VLAN Support
VLAN, according to IEEE 802.1p&q, adds four bytes to the MAC layer of the
Ethernet frame. The contents of these bytes, MAC layer priority and VLAN ID, can
be set by the user. In this mode, only VLAN format frames are sent and received
by IPmux-16. The following figure describes the VLAN tag format.
802.1D Tag Protocol Type
(802.1QTagType)
81 00
user_priority
CF
I =
0
VID
8 6 5 4 1 8 1
Priority VLAN ID
Figure 1-9. VLAN Tag Format
UDP Support
Table 1-2. UDP Source Port as Destination Voice Port
Field Length (Bits) Field Description Value
2 bytes UDP Source Port* 2 – 497d
2 bytes UDP Destination Port 2142d
* The MSB of this field can be either 1 or 0 for inband end-to-end proprietary signaling.
The UDP Source Port field is used for destination voice bundle indication.
For example, if the destination is:
Bundle 1 – 02, Bundle 2 – 03, Bundle 3 – 04, Bundle 4 – 05, etc.
For more information about VLAN tagging, see IEEE Std 802.1 p&q.
Packet Delay Variation
Packets are transmitted at set intervals. Packet Delay Variation is the maximum
deviation from the nominal time the packets are expected to arrive at the far end
device. IPmux-16 has a buffer that compensates for the deviation from the
expected packet arrival time to prevent IPmux-16 buffers from emptying out.
Packet Delay Variation is an important network parameter. Large PDV (exceeding
the jitter buffer configuration) will cause receive buffer underflows and errors at
the E1/T1 level (see Figure 1-10).
To compensate for large PDV, the PDVT (jitter) buffer should be configured to a
higher value.
Note