Avaya IP Phones Uživatelský manuál stáhnout pdf (Strana 258)

Page 258 of 302 Appendix A: 802.1Q VLAN description

553-3001-368 Standard 4.00 February 2005

Note: 802.1Q functionality is supported only on the IP Phone. The IP

Line application's IP stack does not provide 802.1Q support for the

ITG-P or SMC.

Description

The p bits within the 802.1Q standard allow packet prioritization at Layer 2

improving network throughput for VoIP data.

The 802.1Q standard specifies a new format of Ethernet frame. A standard

Ethernet frame contains:

• a header consisting of a six-byte destination MAC address (following the

header is a data area)

• a six-byte source MAC address

• a two-byte protocol identifier

The 802.1Q formatted frame is identical to a standard Ethernet frame, with

the exception of the 4-byte 802.1Q tag that is inserted between the source

MAC address and the protocol identifier. The first 16 bits of the 802.1Q tag

field is the Tag Protocol Identifier containing 8100 (hex), allowing the

Ethernet interface to distinguish it from standard Ethernet frames. The last 16

bits of the 802.1Q tag contain the following information:

• a 3-bit Priority field (the 802.1p defined bits)

• a 1-bit Canonical Field Identifier (CFI)

• a 12-bit VLAN ID field

IP Phone support

The IP Phone 2001, IP Phone 2002 and IP Phone 2004 support 802.1Q as

follows:

• 802.1Q can be enabled or disabled at boot time using manual

configuration or control downloaded from the TPS.

• If 802.1Q is disabled, standard Ethernet frames are transmitted.

1 2 ... 253 254 255 256 257 258 259 260 261 262 263 ... 303 304

Žádné komentáře

Avaya IP Phones Uživatelský manuál Strana 258