Configure VLANs in RTP Proxy

VLAN configuration in RTP Proxy is optional. If you use VLANs on your network, you can configure RTP Proxy to support incoming and outgoing VLAN tagged traffic.

RTP Proxy is designed to support single-tagged VLAN-aware media networks where media traffic is isolated from signalling and management traffic using IEEE 802.1Q VLAN tags. The RTP Proxy supports only single-tagged VLAN (and not double-tagged/Q-in-Q VLAN) because it currently adheres to the IEEE 802.1Q VLAN standard. In such deployments, the media traffic exchanged between the SBC, RTP Proxy and MFE is carried over a dedicated VLAN. When VLAN support is enabled, RTP Proxy is configured to receive and process traffic belonging to the configured VLAN. This allows RTP Proxy to participate in VLAN-aware media forwarding while maintaining traffic isolation across the network.

VLAN Deployment Modes

Two VLAN deployment modes are supported:

  1. Intra-VLAN

    In this deployment, the SBC, MFE, and IAC (or any other downstream element) are configured with the same VLAN ID. For example, the SBC, MFE, and IAC could all use the VLAN ID of 33.

  2. Inter-VLAN

    In this deployment, the SBC is configured with one VLAN ID, while the MFE and IAC (or any other downstream element) are configured with another VLAN ID. For example, the SBC's VLAN ID could be 33 but the VLAN ID of the MFE and IAC could be 35.

    In this deployment, the VLAN ID of the MFE and IAC (and any other downstream elements) must be the same.

VLAN Awareness Types

The SBC can communicate with RTP Proxy by sending either VLAN aware traffic over VLAN interfaces or by sending non-VLAN aware traffic over normal media interfaces. In either case, the RTP Proxy supports multiple types of VLAN awareness.

Type 1: RTP Proxy receives VLAN traffic and sends out VLAN traffic

Use this type when the following conditions are true:

  • The media interface of the SBC is configured as a VLAN interface, and the SBC sends packets with a single-tagged VLAN.
  • The RTP Proxy accepts these media packets that contain VLAN tags and processes them.
  • The RTP Proxy sends media packets to the MFE and the outgoing packets contain VLAN tags.
  • The MFE is VLAN aware and accepts media packets from RTP Proxy; the media interfaces of the MFE are configured as VLAN interfaces.
  • All downstream elements that accept media from MFE are VLAN aware; their media interfaces are configured as VLAN interfaces

The MFE can't convert incoming VLAN traffic to non-VLAN when sending out.


VLAN in to VLAN out

Type 2: RTP Proxy receives non-VLAN traffic and sends out VLAN traffic

Use this type when the following conditions are true:

  • The SBC is not VLAN aware and sends the packets without any VLAN tagging.
  • The RTP Proxy accepts media packets without VLAN tags and processes them.
  • In the RTP Proxy, VLANs are configured on MFE-facing interfaces; the RTP Proxy sends out VLAN tagged media packets.
  • The MFE's media interfaces are configured for VLAN. The MFE accepts VLAN tagged media packets from the RTP Proxy.
  • All downstream elements that accept media from the MFE are VLAN aware. Their media interfaces are configured as VLAN interfaces.

non-VLAN in and VLAN out

Type 3: RTP Proxy receives VLAN traffic and sends out non-VLAN traffic

Use this type when the following conditions are true:

  • The SBC is VLAN aware and sends the packets with single-tagged VLAN.
  • The RTP Proxy accepts these media packets with VLAN tags and processes them.
  • The RTP Proxy sends out media packets without VLAN tags to the MFE. The MFE-facing interface on the RTP Proxy is not VLAN enabled.
  • The MFE accepts media packets from the RTP Proxy without VLAN tags. The media interfaces of MFE can be normal interfaces and need not be configured as the VLAN interfaces.
  • All downstream elements that accept the media from the MFE are not VLAN aware. Their media interfaces are normal interfaces and not configured as VLAN interfaces.

VLAN in to non-VLAN out

When setting up the VLAN awareness of downstream elements in your network, like the IAC, follow these two rules:
  1. If the MFE is VLAN aware, all downstream elements must be VLAN aware.
  2. If the MFE is not VLAN aware, all downstream elements must not be VLAN aware.

If the MFE is VLAN aware, your IAC must also be VLAN aware. Similarly, if your MFE is not VLAN aware, your IAC must not be VLAN aware.

For details on configuring the SBC's media interfaces with VLAN, see the SBC Configuration Guide.

Switch Configuration

The switch ports connected to the RTP Proxy host must be configured to carry the VLAN used for media traffic. Configure the switch ports as 802.1Q trunk ports and allow the required VLAN (for example, VLAN 33) on those ports. This ensures that VLAN-tagged packets are forwarded between the switch and the host without removing the VLAN tag, allowing the guest virtual machines and RTP Proxy to process VLAN-aware media traffic.

See the documentation for your switch provider for how to enable VLAN support.

A sample configuration:
interface Ethernet29
   switchport trunk allowed vlan 33
   switchport mode trunk

interface Ethernet3
   switchport trunk allowed vlan 35
   switchport mode trunk