Table of contents

The ODR protocol

ODR (On Demand Routing) is a routing protocol used in networks having a star topology. The point-to-multipoint topology is a star topology, so ODR is widely used in wireless networks. The ODR algorithm, unlike the other dynamic routing protocols, is very simple, so its operation is not resource-intensive.

Let's look at the ODR's protocol operation based on the example in (Figure 1). The network scheme consists of a base station BS1 and three subscriber devices CPE2, CPE3 and CPE4, connected to BS1. A local network segment with its own IP addressing is present behind each wireless device. An IP subnet is also assigned to the MINT area.

Figure 1 - The ODR protocol's operational scheme in a star topology network


Table 1 - The routing tables of the wireless devices after pre-configuration

Table 2 - The routing tables of the wireless devices after the ODR configuration

Usually, the ODR protocol is used in PTMP schemes (Figure 1), however, for a better understanding, let's complicate the scheme by implementing the load balancing and fault tolerance functions (Figure 2):

Please note that the role is not a device characteristic, but a state of an interface that supports the MINT protocol's operation. For example, a wireless device can be a hub in the MINT area to which it is connected via the rf5.0 interface, and it can be a spoke in the MINT area connected via the prf0 interface. In the example below, one common MINT area is used, therefore, for the BS1 and BS2 devices, it is enough to activate the ODR protocol support on one of the interfaces that support MINT.

After the preliminary configuration and the role distribution, CPE11, CPE12, CPE21 and CPE22 will add a default route to the routing table, specifying InfiMUX1 or InfiMUX2 as the gateway. The gateway will be selected by the lowest metric value. Each hub device will receive routing information about the end-user networks LAN-11, LAN-12, LAN-21, and LAN-22 from the devices having spoke roles. Devices BS1 and BS2 are intermediate in this scheme and do not transmit routing information to the devices with the hub role.

Fault tolerance: let's say that the whole traffic passing through BS1 also passes through InfiMUX1, and BS2's traffic - through InfiMUX2. If InfiMUX1 fails, then the BS1, CPE11 and CPE12 devices will delete the entry having the InfiMUX1 as gateway from the routing table and will add another default route via InfiMUX2. A similar situation will occur in case of failure of the InfiMUX 2.

Load balancing: the default route metric in ODR is calculated based on the radio parameters and on the channel's load level. This allows to balance the traffic for the spoke devices and evenly make use of the devices and of the communication channels in the MINT area.

Figure 2 - Redundancy scheme using the ODR protocol

ODR protocol features

Unlike static routing, the ODR protocol has the following features:

Examples of the ODR configuration are included in the child page document: ODR protocol configuration.

Additional materials

Online courses

  1. InfiLINK 2x2 / InfiMAN 2x2: Initial Link Configuration and Installation.
  2. InfiLINK 2x2 and InfiMAN 2x2: Switching

Webinars

  1. Typical scenario of routing setting using Infinet Wireless devices. Part I.

Other

  1. Network configuration via web interface for InfiLINK 2x2, InfiMAN 2x2.

  2. Network configuration via Web interface for InfiLINK Evolution, InfiMAN Evolution families devices.
  3. Ifconfig command (interfaces configuration)
  4. route command (static routes configuration)
  5. mint command (MINT version)
  6. mint command (TDMA version)