There are some enhancements that affect how ADAC/LLDP function on the ERS 5520 switch. From the release notes;

IEEE 802.1ab and ADAC linkage
Nortel introduced the 802.1ab and Auto Detection Auto Configuration(ADAC) features to Release 5.0 to address converged applications. In Release 5.1, the functionality of 802.1ab and ADAC is combined: ADAC uses 802.1ab/LLDP as the detection mechanism to determine the identity of the attached device (that is, a Nortel IP phone that supports 802.1ab Media Endpoint Devices type, length, and value descriptions [MED TLV]). The Auto Configuration functionality of ADAC applies the configuration to the port.
Configurable using NNCLI, ACG, and Device Manager.

It looks like it will no longer be necessary to maintain the list of MAC prefixes for all Nortel Internet Telephones. If you recall from some of my previous posts I needed to manually update the list of MAC prefixes used by my ERS 5520 switches in order to get many of my i2002/i2004 Internet Telephones to be detected properly. The default list of MAC prefixes usually didn’t cover all the i2002/i2004/i2007/1140e Internet Telephones I had installed throughout my organization. In previous articles we enabled ADAC like so;

5520-48T-PWR (config)# adac voice-vlan 50
5520-48T-PWR (config)# adac op-mode tagged-frames
5520-48T-PWR (config)# adac uplink-port 48
5520-48T-PWR (config)# adac mac-range-table low-end 00:18:b0:00:00:00 high-end 00:18:b0:ff:ff:ff
5520-48T-PWR (config)# adac mac-range-table low-end 00:16:ca:00:00:00 high-end 00:16:ca:ff:ff:ff
5520-48T-PWR (config)# adac mac-range-table low-end 00:17:65:00:00:00 high-end 00:17:65:ff:ff:ff
5520-48T-PWR (config)# adac mac-range-table low-end 00:0a:e4:75:00:00 high-end 00:0a:e4:75:ff:ff
5520-48T-PWR (config)# adac mac-range-table low-end 00:14:c2:00:00:00 high-end 00:14:c2:ff:ff:ff
5520-48T-PWR (config)# adac mac-range-table low-end 00:19:69:00:00:00 high-end 00:19:69:ff:ff:ff
5520-48T-PWR (config)# adac mac-range-table low-end 00:19:e1:00:00:00 high-end 00:19:e1:ff:ff:ff
520-48T-PWR (config)# adac enable

I haven’t actually tested this myself yet but supposedly if LLDP detects an Internet Telephone it will pass that information to ADAC without the need of evaluating the device’s MAC address.

The 5.1 release also now supports the 1000Base-BX SFP;

BX SFP support
Many customers have high density gigabit requirements, but lack the fiber density to deploy. BX SFPs helps alleviate this issue by allowing a single strand of fiber to facilitate communication.
Nortel introduces support for 1000BaseBX10 module with release 5.1. The modules are single fiber, bidirectional SFP transceivers. Two types of modules are available:
• 1310nm (BX10-U) transceiver
• 1490nm (BX10-D) transceiver
The 1000BaseBX10-D device is always connected to a 1000BaseBX10-U device with a single strand of standard single-mode fiber. The operating transmission range is up to 10 km. The fiber uses a GBIC LC connector on each end.
If the 1000BaseBX10-U is not connected to the 1000BaseBX10-D device, the signals are not received properly and the Link LED does not illuminate. You can configure BX SFP Support through the NNCLI, ACG, or Device Manager.

The 1000BASE-BX bidirectional SFPs provide Gigabit Ethernet connectivity over a single fiber.

As shown in the figure, the transmit (Tx) and receive (Rx) paths share the same fiber by using two different wavelengths. One model transmits at 1310 nm and receives at 1490 nm, while the mating model transmits at 1490 nm and receives at 1310 nm. You can only connect a mating pair.

You can use 1000BASE-BX SFPs to double the number of your fiber links. For example, if you have 20 installed fiber pairs with 20 conventional ports connected, you can use 1000BASE-BX SFPs to expand to 40 ports, using the same fiber.

The long wavelength optical transceivers used in these models provide variable distance ranges using single mode fiber optic cabling.

Cheers!