Cisco IOS XR software is a distributed operating system designed for continuous system operation
combined with service flexibility and high performance.

Cisco IOS XR software provides the following features and benefits:

•

IP and Routing—Supports a wide range of IPv4 and IPv6 services, and routing protocols, such as
Border Gateway Protocol (BGP), Intermediate System-to-Intermediate System (IS-IS), Open
Shortest Path First (OSPF), IP Multicast, Routing Policy Language (RPL), and Hot Standby Router
Protocol (HSRP)/Virtual Router Redundancy Protocol features (VRRP).

•

Bidirectional forwarding detection (BFD)—Provides low-overhead, short-duration detection of
failures in the path between adjacent forwarding engines. BFD allows a single mechanism to be used
for failure detection over any media and at any protocol layer, with a wide range of detection times
and overhead. The fast detection of failures provides immediate reaction to failure in the event of a
failed link or neighbor. OSPF, ISIS, BGP, and MPLS-TE FRR use BFD to detect failures. (CRS-1
only)

•

MPLS—Supports Multiprotocol Label Switching (MPLS) protocols such as Traffic Engineering
(TE), Resource Reservation Protocol (RSVP), and Label Distribution Protocol (LDP).

•

Multicast—Provides comprehensive IP Multicast software including Source Specific Multicast
(SSM). The Cisco CRS-1 platform supports Bidirectional Protocol Independent Multicast
(BIDIR-PIM).

•

Quality of service (QoS)—Supports rich QoS mechanisms including policing, marking, queuing,
dropping, and shaping. Additionally, the operating systems support Modular QoS CLI (MQC).
MQC is used to configure various QoS features on various Cisco platforms.