Introduction to Radio Aware Routing and MANET
After configuring the interfaces and verifying connectivity as described in “Configuring the Interfaces,” you will need to configure each interface with the appropriate protocol.
This chapter provides the following major sections to describe Radio Aware Routing (RAR) for use in a Mobile Ad-hoc Network (MANET):
Introduction to RAR
The Radio Aware Routing (RAR) strategy relies on a hierarchy of routing interfaces. At the top-most level is the Virtual Multipoint Interface, or VMI. The VMI provides a single, unified representation of the MANET to routing protocols (OSPFv3 or EIGRP), and to the rest of the attached topology.
For traffic originating outside the MANET, the VMI represents the ingress and egress point to and from the MANET. As traffic comes into the router, destined for the MANET, the router passes the traffic to the VMI interface. The VMI, in turn, fans the traffic out (based on destination) to the correct Virtual-Access interface, where QoS policy can be applied to queue the traffic based on the radio characteristics of the next hop. After applying (potentially different) QoS parameters on the Virtual-Access interfaces, the Virtual-Access interface funnels the traffic to the physical interface for transmission to the radio device.
The Virtual-Access interfaces are logically “underneath” the VMI interface. Each Virtual-Access interface represents a “destination” which is either a routing next-hop, or a multicast group. The QoS logic and associated queues on the Virtual-Access interfaces facilitate the fine-grained QoS. The Virtual-Access interface that exists for each next-hop or group gives the ability to vary QoS behavior on a hop-by-hop (or group-by-group) basis.
At the bottom of the interface hierarchy is the actual physical interface connecting the router and radio.
MANET Protocols
The protocols described in this guide support Mobile Ad-hoc Networks (MANETs). MANET-routing protocols provide signaling among MANET routers, including scope-limited flooding and point-to-point delivery of MANET routing protocol signaling in a multi-hop network. Packets may be unicast or multicast and use any appropriate transport protocol.
The RAR protocols supported Cisco IOS Release 15.2(1)GC provide the capabilities listed in Table 5-1.
Table 5-1 RAR Protocols
|
|
Dynamic Link Exchange Protocol (DLEP)
|
|
Point-to-Point Protocol over Ethernet (PPPoE) |
UDP |
|
Point-to-Point Point to Multipoint |
Broadcast Multi-access |
|
Credit or Rate-based |
Rate-based |
|
Yes |
Yes |
|
Defined in RFC 5578 |
Same metrics as RFC 5578 |
|
Split-stack PPPoE to router |
UDP to router Transparent bridge on data path |
|
Informational |
Standards-track (submitted, not yet approved) |
Supports Modem Multiple Hops from Router
|
No, PPPoE discovery is broadcast |
Yes |
|
Available for client only |
Available for both client and server |
|
Chapter 8, “Configuring PPPoE” |
Chapter 6, “Understanding and Configuring DLEP” |
Table 5-2 lists the routing protocols that support RAR and MANET:
Table 5-2 Routing Protocols that Support RAR and MANET
|
|
Open Shortest Path First, Version 3 (OSPFv3) |
Chapter 10, “Configuring OSPFv3 for a MANET” |
Enhanced Interior Gateway Routing Protocol (EIGRP) |
Chapter 11, “Configuring EIGRP in a MANET” |
Understanding Virtual Templates
Each RAR protocol requires a virtual template. The virtual template is used to create Virtual-Access interfaces. All Virtual-Access interfaces inherit the attributes of the virtual template. When configuring each RAR protocol, you will assign a virtual-template number. To configure virtual templates for each RAR protocol, see the chapter in this manual on the specific protocol.
Configuring QoS
When using RAR, QoS is applied at the Virtual-Access interfaces. Defining and enforcing QoS profiles is configured on a next-hop basis. Traffic prioritization to one peer system should not impact traffic prioritization to other peers.
Configuring Quality of Service (QoS) varies per protocol:
- MQC—For RFC 5578, DLEP, and Modular QoS CLI (MQC) configurations are supported. Full MQC configurations include remarking, shaping, and policing.
- CDR-based QoS—For DLEP and QoS configuration is based entirely on Current Data Rate (CDR) shaping.
For more information about CDR-based QoS configurations, see CDR-based QoS, page 5-3.
QoS Configuration Types
Configuring Quality of Service (QoS) can follow one of various approaches:
CDR-based QoS
The only QoS configuration required for DLEP or R2CP is the shaping definition. When DLEP or R2CP detects a new neighbor, a set of metrics is exchanged from radio to router. These metrics include a Current Data Rate (CDR) value. When configuring rate-based shaping, the router shapes the traffic destined for each neighbor based on its CDR rate.
Reporting CDR Values
When using rate-based shaping, the parent policy includes a percent value for the shaping command. This allows the radio to report a different CDR value and the shaping to adapt to the new value on the router. While you can use a static bandwidth on the shaping command, it may not represent the link properly, resulting in traffic that can queue unpredictably.