Sunday, 5 July 2015

LLDP-MED


MED is an extension for LLDP that support additional TLVs. LLDP-MED supports the following three classes of endpoints:

  • Generic (class 1): Basic participant endpoints; for example, IP communications controllers.
  • Media (class 2): Endpoints that support media streams; for example, media gateways and conference bridges.
  • Communication Device (class 3): Endpoints that support IP communications end users; for example, IP phones and Softphone.

By default, a network connectivity device (e.g. switch) sends out only LLDP packets until it receives LLDP-MED packets from an endpoint device (e.g. IP Phone). The network device then sends out LLDP-MED packets until the remote device to which it is connected ceases to be LLDP-MED capable.

The additional TLVs supported can be groups as (by default all MED TLVs are enabled):

  • Capabilities TLV — Endpoints determine the types of capabilities that a connected device supports and which ones are enabled.

MED Information:

    MED Codes:
          (NP) Network Policy, (LI) Location Identification
          (PS) Power Source Entity, (PD) Power Device
          (IN) Inventory

    H/W revision: 14
    F/W revision: tnp45.9-3-1-CR17.bin
    S/W revision: SCCP45.9-4-2-1S
    Serial number: FCH1714A7PV
    Manufacturer: Cisco Systems, Inc.
    Model: CP-7945G
    Capabilities: NP, PD, IN
    Device type: Endpoint Class III
    Network Policy(Voice): VLAN 104, tagged, Layer-2 priority: 5, DSCP: 46
    Network Policy(Voice Signal): VLAN 104, tagged, Layer-2 priority: 4, DSCP: 32
    PD device, Power source: Unknown, Power Priority: Low, Wattage: 12.0
    Location - not advertised

  • Inventory TLV — LLDP-MED support exchange of hardware, software, and firmware versions, among other inventory details.

MED Information:

    MED Codes:
          (NP) Network Policy, (LI) Location Identification
          (PS) Power Source Entity, (PD) Power Device
          (IN) Inventory

    H/W revision: 14
    F/W revision: tnp45.9-3-1-CR17.bin
    S/W revision: SCCP45.9-4-2-1S
    Serial number: FCH1714A7PV
    Manufacturer: Cisco Systems, Inc.
    Model: CP-7945G
    Capabilities: NP, PD, IN
    Device type: Endpoint Class III
    Network Policy(Voice): VLAN 104, tagged, Layer-2 priority: 5, DSCP: 46
    Network Policy(Voice Signal): VLAN 104, tagged, Layer-2 priority: 4, DSCP: 32
    PD device, Power source: Unknown, Power Priority: Low, Wattage: 12.0
    Location - not advertised

  • LAN speed and duplex TLV — Devices discover mismatches in speed and duplex settings.
  • Location identification TLV — An endpoint, particularly a telephone, learns its location from a network device. This location information may be used for location-based applications on the telephone and is important when emergency calls are placed.

MED Information:

    MED Codes:
          (NP) Network Policy, (LI) Location Identification
          (PS) Power Source Entity, (PD) Power Device
          (IN) Inventory

    H/W revision: 14
    F/W revision: tnp45.9-3-1-CR17.bin
    S/W revision: SCCP45.9-4-2-1S
    Serial number: FCH1714A7PV
    Manufacturer: Cisco Systems, Inc.
    Model: CP-7945G
    Capabilities: NP, PD, IN
    Device type: Endpoint Class III
    Network Policy(Voice): VLAN 104, tagged, Layer-2 priority: 5, DSCP: 46
    Network Policy(Voice Signal): VLAN 104, tagged, Layer-2 priority: 4, DSCP: 32
    PD device, Power source: Unknown, Power Priority: Low, Wattage: 12.0
    Location - not advertised

  • Network policy TLV — Network connectivity devices notify telephones about the VLANs they should use, CoS, and DSCP settings.

MED Information:

    MED Codes:
          (NP) Network Policy, (LI) Location Identification
          (PS) Power Source Entity, (PD) Power Device
          (IN) Inventory

    H/W revision: 14
    F/W revision: tnp45.9-3-1-CR17.bin
    S/W revision: SCCP45.9-4-2-1S
    Serial number: FCH1714A7PV
    Manufacturer: Cisco Systems, Inc.
    Model: CP-7945G
    Capabilities: NP, PD, IN
    Device type: Endpoint Class III
    Network Policy(Voice): VLAN 104, tagged, Layer-2 priority: 5, DSCP: 46
    Network Policy(Voice Signal): VLAN 104, tagged, Layer-2 priority: 4, DSCP: 32
    PD device, Power source: Unknown, Power Priority: Low, Wattage: 12.0
    Location - not advertised

  • Power TLV — Network connectivity devices and endpoints exchange power information. LLDP-MED provides information about how much power a device needs, power priority (for the switch to decide the order to allocate power to endpoints), and how a device is powered.

MED Information:

    MED Codes:
          (NP) Network Policy, (LI) Location Identification
          (PS) Power Source Entity, (PD) Power Device
          (IN) Inventory

    H/W revision: 14
    F/W revision: tnp45.9-3-1-CR17.bin
    S/W revision: SCCP45.9-4-2-1S
    Serial number: FCH1714A7PV
    Manufacturer: Cisco Systems, Inc.
    Model: CP-7945G
    Capabilities: NP, PD, IN
    Device type: Endpoint Class III
    Network Policy(Voice): VLAN 104, tagged, Layer-2 priority: 5, DSCP: 46
    Network Policy(Voice Signal): VLAN 104, tagged, Layer-2 priority: 4, DSCP: 32
    PD device, Power source: Unknown, Power Priority: Low, Wattage: 12.0
    Location - not advertised

Network Policy TLV

In case the network connectivity device (e.g. switch)  doesn't have a network policy configured, the network policy TLV will show the parameters received from the endpoint (e.g. IP Phone). These parameters might be assigned to the endpoint by different source (e.g. CUCM).

However, you can configure a network policy on the network connectivity device (e.g. switch) to be pushed to the endpoint using MED TLV. These parameters will override any other parameters assigned to the endpoint.

Important

While many Cisco IP Phones may support LLDP-MED, they do so only for VLAN and Power over Ethernet negotiation. Cisco IP Phones do not honor DSCP and CoS markings provided by LLDP-MED.

network-policy profile 1
 voice vlan 96 dscp 12
 voice-signaling vlan 96 dscp 13 ….. You can't assign different vlans to voice and signaling. If happened, the voice vlan will override the signaling vlan.
!
interface GigabitEthernet0/5
 network-policy 1

Note: If you assign a network policy to an interface, it will override the command 'switchport access voice vlan #'.

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