RAD Data comm IPmux-16 operation manual Packet Delay Variation, Vlan Support, UDP Support

IPmux-16Installation and Operation Manual Chapter 1 Introduction

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.

81 00

802.1D Tag Protocol Type

(802.1QTagType)

user_priority		0				VID
		CFI =
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.

Note 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.

Functional Description 1-11