The MPLS-TE auto-bandwidth feature allows to resize the tunnels based on the measured traffic load. The autobandwidth bundle TE++ feature is an extension of the auto-bandwidth feature. This feature allows to automatically increase or decrease the number of MPLS-TE tunnels to a destination based on real time traffic needs. Hence, this feature helps to avoid large LSPs and enables load sharing the traffic between source and destination.

For more information about configuring the Autobandwidth bundle TE++ feature, see MPLS Configuration Guide for Cisco NCS 540 Series Routers.

BGP Flow Specification version 4 and version 6 feature allows you to receive IPv4 and IPv6 traffic flow specifications and actions that need to be taken on that traffic through BGP update. This feature allows you to rapidly deploy and propagate filtering and policing functionality among a large number of BGP peer routers to mitigate the effects of a distributed denial-of-service (DDoS) attack over your network.

For more informnation about the feature, see the chapter Implementing BGP in the BGP Configuration Guide for Cisco NCS 540 Series Routers.

Cisco IOS XR supports programmability of OC NI, OC local routing, OC-MPLS, OC-RSVP-SR, OC-RPL and OC-BGP-Policy OpenConfig data models for configuration and operational data.

For more information about YANG data models and configuration, see Using Data Models chapter in Programmability Configuration Guide for Cisco NCS 540 Series Routers

The following enhancements are introduced in Release 6.5.1:

• During the fresh boot, to establish a secured connection with DHCP server, authentication is performed on data ports through DHCP option 43 for IPv4 and option 17 for IPv6. These DHCP options are defined in option space and included within dhcpd.conf/dhcpd6.conf configuration files.

• During the fresh boot of a router auto ZTP process is initiated from the management port and switches to data port when:

  • ZTP does not find an active interface,

  • delay in DHCP response, and

  • ZTP encounters an error.

  Note	The auto breakout mode is not supported.

• During fresh boot of the router or manual invocation of ZTP, IPv6 is enabled on all dataports (in dataport mode).

• The log file ztp.log is saved in /var/log folder, and a copy of log file is available at /disk0:/ztp/ztp.log location using a soft link. However, executing ztp clean command clears files saved on disk and not on /var/log folder where current ZTP logs are saved. In order to have a log from current ZTP run, you must manually clear the ZTP log file from /var/log/ folder.

• When ZTP process encounters any error, or when ZTP quits or terminates, it reverts to the initial configuration that exists before starting of ZTP process.

For more information on Auto ZTP feature, see the chapter Configuring Zero Touch Provisioning in the System Management Configuration Guide for Cisco NCS 540 Series Routers

The EVPN Single-Active Multi-Homing feature supports single-active redundancy mode. In single-active mode, the provider edge (PE) nodes locally connected to an Ethernet Segment load balance traffic to and from the Ethernet Segment based on EVPN service instance (EVI). Within an EVPN service instance, only the Designated Forwarder (DF) PE forwards traffic to and from the Ethernet Segment.

Seamless integration of EVPN MPLS with VPLS enables the co-existence of PE nodes running EVPN and VPLS for the same VPN instance. VPLS or legacy network can be upgraded to the next generation EVPN network without service disruption. You can introduce EVPN service on all the selected VPLS provider edge (PE) nodes simultaneously. However, to avoid traffic disruption, provision EVPN service on existing VPLS-enabled PEs one by one.

For more information on this feature, see the EVPN Features chapter in the L2VPN and Ethernet Services Configuration Guide for Cisco NCS 540 Series Routers.

The G.8032 Ethernet Ring Protection feature provides protection for Ethernet traffic in a ring topology. This feature prevents loops within the ring at the Ethernet layer by blocking either a pre-determined link or a failed link.

For more information on this feature, see the Configure Point-to-Point Layer 2 Services chapter in the L2VPN and Ethernet Services Configuration Guide for Cisco NCS 540 Series Routers.

Earlier, in IOS-XR platforms, LLDP was enabled only with global LLDP configuration and administrators had to manually disable each interface.

With this feature, you can now enable the global LLDP configuration per-interface basis. To enable the feature, you must make the necessary configuration changes. For more information on the feature, see the Interface and Hardware Component Configuration Guide for Cisco NCS 540 Series Routers.

A shared risk link group (SRLG) is a set of links sharing a common resource and hence shares the same risk of failure. The current implementation of SRLG protection considers only the directly connected links. Hence, if the router that computes the backup path includes a link that is not directly connected but shares the same SRLG, the SRLG protection fails. The global weighted SRLG protection feature provides better path selection for the SRLG by associating a weight with the SRLG value and using the weights of the SRLG values while computing the backup path.

For more information about configuring the global weighted SRLG protection feature, see MPLS Configuration Guide for Cisco NCS 540 Series Routers.

Highest Random Weight (HRW) Mode for EVPN DF Election feature provides optimal load distribution of Designated Forwarder (DF) election, redundancy, and fast access. It ensures a non-disruptive service for an Ethernet Segment (ES) irrespective of the state of a peer DF.

IS-IS Authentication with Keychain feature enables the support of Hashed Message Authentication Code (HMAC) and Cipher-based Message Authentication Code (CMAC) during IS-IS authentication. New cryptographic algorithms such as, AES-128-CMAC-96, HMAC-SHA-256, and HMAC-SHA1-96 are added under Keychain infra as part of this feature. These algorithms provide more secured authentication.

Keychains can be configured at the router level (in case of the lsp-password command) and at the interface level (in case of the hello-password command) within IS-IS. These commands refer to the global keychain configuration and instruct the IS-IS protocol to obtain security parameters from the global set of configured keychains.

For more information about Keychain configuration, see Implementing Keychain Management Chapter of the System Security Configuration Guide for Cisco NCS 540 Series Routers.

This feature allows users to specify a filter based on destination prefix list or route policy, and use that filter to prevent routes computed by Intermediate System-to-Intermediate System (IS-IS) from being installed in the Routing Information Base (RIB).

When distribute-list in command is configured, some routes that IS-IS computes are not installed in the forwarding plane of the local router, but other IS-IS routers will not be aware of this. This introduces a difference between the forwarding state computed by other IS-IS routers and the actual forwarding state on this router. In some cases, this could lead to traffic being dropped or looped. Hence, be careful about when to use this command.

For more information about the distribute-list in command, see Routing Command Reference for Cisco NCS 5500 Series Routers and Cisco NCS 540 and NCS 560 Series Routers.

For more information about this feature, see Implementing IS-IS Chapter of the Routing Configuration Guide for Cisco NCS 540 Series Routers.

An adjacency SID is typically associated with a Layer 3 adjacency to a neighboring node. If you have Layer 2 bundle interfaces, where multiple physical interfaces form a bundle interface, the individual Layer 2 bundle members are not visible to IGP; only the bundle interface is visible.

The Layer 2 Adjacency SID feature provides adjacency SID functionality for individual bundle members. This feature allows you to track the availability of individual bundle member links and to verify the segment routing forwarding over the individual bundle member links, for Operational Administration and Maintenance (OAM) purposes. A Layer 2 adjacency SID can be allocated dynamically or configured manually.

For more information on this feature, see the Configure Segment Routing for IS-IS Protocol chapter in the Segment Routing Configuration Guide for Cisco NCS 540 Series Routers.

This feature specifies the TCP Authentication Option (TCP-AO) that replaces the TCP MD5 option. TCP-AO uses the Message Authentication Codes (MACs), which provides the following:

• protection against replays for long-lived TCP connections

• more details on the security association with TCP connections than TCP MD5

• a larger set of MACs with minimal other system and operational changes.

Cisco provides the MKT configuration by means of the following configurations:

• keychain configuration

• tcp tcp-ao keychain configuration

For more information on this feature, see BGP Configuration Guide for Cisco NCS 540 Series Routers.

The hw-module profile load-balance algorithm command provides the ability to modify the hashing algorithm used for ECMP and bundle member selection. Effective with Cisco IOS XR release 6.5.1, this command is enhanced to include GPRS tunneling protocol (GTP) mode which allows hashing based upon the tunnel id in GTP-U packets.

For more information about the hw-module profile load-balance algorithm command, see Interface and Hardware Component Command Reference for Cisco NCS 5500 and NCS 540 and NCS 560 Series Routers.

The Minimum Remaining Lifetime for IS-IS feature helps to maintain the stability of the network when the Remaining Lifetime field in a Link State Protocol (LSP) is corrupted. Corruption of the Remaining Lifetime field in a LSP data unit can go undetected. In certain scenarios, this may cause or exacerbate flooding of LSPs. This feature resolves this problem by enabling IS-IS to reset the Remaining Lifetime value of the received LSP, to the maximum LSP lifetime (1200 seconds), if the Remaining Lifetime value of the received LSP is less than the maximum LSP lifetime configured in a local node. If the received LSP lifetime value is less than the Zero Age Lifetime (60 seconds), IS-IS generates an error message indicating that it’s a corrupted lifetime event.

IS-IS saves the received Remaining Lifetime value in LSP database. The value is shown in the show isis database command output under the Rcvd field.

For more information about the show isis database command, see IS-IS Commands Chapter of the Routing Command Reference for Cisco NCS 5500 Series Routers and Cisco NCS 540 and NCS 560 Series Routers.

For more information about this feature, see Implementing IS-IS Chapter of the Routing Configuration Guide for Cisco NCS 540 Series Routers.

The Multicast Label Distribution Protocol (MLDP) feature is enhanced to support the edges; that is, the encapsulation (headend) and the decapsulation (tailend) at the Provider Edge (PE) devices. The MLDP Edge feature enables service providers to extend the existing MPLS backbone network for multicast services. This feature extends the functionality from midpoint to support the edges - the headend and the tailend.

Earlier than Cisco IOS XR Release 6.5.1, MLDP VRF In-band Signaling (profile 6) and Global Inband Signaling (Profile 7) was supported only at the core, now it is supported on the edge as well.

For more information about this feature, see Implementing Multicast Chapter of the Multicast Configuration Guide for Cisco NCS 540 Series Routers.

The Multiple Spanning Tree Access Gateway (MSTAG) feature provides a mechanism to block the redundant path to avoid a loop. This feature enables the provider edge (PE) devices to flush the MAC addresses over VPLS network to prevent unreported traffic drops.

OSPF Authentication with Keychain feature enables the support of Hashed Message Authentication Code (HMAC) during OSPF authentication. New crypto algorithms such as, HMAC-SHA-256 and HMAC-SHA1-96 are added under key-chain infra as part of this feature. These algorithms provide more secured authentication.

Keychains can be configured at different levels of OSPF like at the router level, or the area level, or the interface level.

Label switched multicast (LSM) is an MPLS technology extension to support multicast using label encapsulation.The label encapsulation could be either point-to-multipoint (P2MP) label switched paths (LSPs) or multipoint-to-multipoint (MP2MP) LSPs. For creating multicast LSPs, two protocol extensions can be used. The RSVP-TE protocol is extended to signal P2MP LSPs across the MPLS networks which is known as P2MP RSVP-TE. Multicast Label Distribution Protocol (MLDP) provides extensions to the label distribution protocol (LDP) for the setup of P2MP and MP2MP LSPs.The point-to-multipoint traffic-engineering (P2MP-TE) feature implements P2MP RSVP-TE on Cisco NCS 540 series routers.

For more information about configuring the P2MP-TE feature, see MPLS Configuration Guide for Cisco NCS 540 Series Routers.

Prior to Cisco IOS XR Release 6.5.1, the configurations committed in a newly created interface are lost when:

• you do not issue no shutdown command to remove the default shutdown config, and

• you issue no shutdown command and reload the router.

From Release 6.5.1, onwards, automatic shutdown config behavior is persistent and configurations are intact whether or not the default shhutdown config is removed and even if the router is reloaded.

For more information on the feature, see interface (global) command in the Global Interface Commands chapter of the Interface and Hardware Component Command Reference for Cisco NCS 5500 and NCS 540 and NCS 560 Series Routers

Resilient Hashing and Flow Auto-Recovery feature provides an option to selectively override the default equal cost multipath (ECMP) behavior during a ECMP path failure. This feature enables the redirection of flows through inactive links only and the prevention of all existing flows from being rehashed to a new link. This feature also provides an option to recover a link or a server when it comes back so it can be reused for sessions.

For more informnation about the feature, see the chapter Implementing BGP in the BGP Configuration Guide for Cisco NCS 540 Series Routers.

The Pseudowire Redundancy feature allows you to configure a redundant pseudowire that backs up the primary pseudowire. When the primary pseudowire fails, the PE router switches to the redundant pseudowire. You can elect to have the primary pseudowire resume operation after it becomes functional. The primary pseudowire fails when the PE router fails or when there is a network outage.

For more information on this feature, see the Configure Point-to-Point Layer 2 Services chapter in the L2VPN and Ethernet Services Configuration Guide for Cisco NCS 540 Series Routers.

At present, an IS-IS purge does not contain any information to identify the Intermediate System (IS) that generates the purge. This makes it difficult to locate the source IS.

To address this issue, the Purge Originator Identification (POI) TLV for IS-IS feature defines a type, length, and value (TLV) that can be added to the purges, to record the system ID of the IS that had initiated the purge. This makes it easier to locate the origin of the purge and its cause. If you are using cryptographic authentication, then the enable-poi keyword in lsp-password command must be enabled to insert the Purge Originator Identification (POI). If you are not using cryptographic authentication, then the POI is inserted by default. This TLV is also helpful in lab environments.

For more information about this feature, see Implementing IS-IS Chapter of the Routing Configuration Guide for Cisco NCS 540 Series Routers.

QoS Policy Propagation via BGP (QPPB,) is a mechanism that allows propagation of quality of service (QoS) policy and classification by the sending party based on access lists, community lists and autonomous system paths in the Border Gateway Protocol (BGP), thus helping to classify based on destination instead of source address.

With the enablement of this feature, you can configure QPPB on NCS 540. For more information on the feature, see Modular QoS Configuration Guide for Cisco NCS 540 Series Routers.

RPF vector is a PIM proxy that lets core routers without RPF information forward join and prune messages for external sources (for example, a MPLS-based BGP-free core, where the MPLS core router is without external routes learned from BGP). The RPF vector encoding is now compatible with the new IETF encoding. Use the rpf-vector use-standard-encoding command to enable the feature.

For more information on RPF, see the Implementing Layer-3 Multicast Routing chapter in the Multicast Configuration Guide for Cisco NCS 540 Series Routers

Golden ISO (GISO) upgrades to a version that has a predefined list of software maintenance update (SMUs) with a single operation. However, to update to the same version with a different set of SMUs requires a two-step process. This two-step process can be avoided using the install update replace functionality to replace the currently active version with the full package including the image and SMUs from the newly added GISO.

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The Resilient Ethernet Protocol Access Gateway (REPAG) feature provides a mechanism to block the redundant path to avoid a loop. This feature enables the provider edge (PE) devices to flush the MAC addresses over VPLS network to prevent unreported traffic drops.

The REPAG feature provides the same functionality as MSTAG, but in REPAG the access network runs REP and not multiple spanning tree (MST) protocol.

This feature provides resolution to prevent RDSFS process crash, and memory leakage at Name Registration Service (NRS) and Replicated Data Services File System (RDSFS) Server due to large number of configuration commits. To achieve this, nrs_purge API is enhanced to purge the NRS handles for files that are already deleted. This resolution provides significant improvements in the following aspects:

• Enables a large number of configuration commits, without any issues

• Ensures lower memory consumption for NRS server and RDSFS processes.

• Prevents the need to reload the router when it has to recover from the following scenarios:

  • Continuous restarting or crashing of RDSFS processes

  • Not being able to commit any configurations

When a router is part of an RSVP-TE network and an segment routing (SR) network, the Multiprotocol Label Switching (MPLS) drop counters do not indicate if the dropped packets are in an RSVP-TE network or an SR network. The show cef mpls drops command displays MPLS drop counters for packets that belong to a segment routing (SR) network.

The incoming top MPLS label is inspected. If the label belongs to the Segment Routing Local Block (SRLB) or the Segment Routing Global Block (SRGB), an MPLS SR drop counter is incremented for unknown label value.

For more information on this command, see the Cisco Express Forwarding Commands chapter in the IP Addresses and Services Command Reference for Cisco NCS 5500 Series and NCS 540 Series Routers.

XR-VM supported a global configuration to exit service cli submode on all configuration session for all Virtual Terminal Type lines (VTY) earlier. But, you would need a knob to enable this feature specific to a VTY.

Cisco IOS XR now supports a configuration to exit service cli submode on all interactive configuration sessions for each VTY using terminal commands. The command, terminal cli submode-exit lets you enable or disable submode-exit on all interactive configuration sessions for each VTY. You can use the show cli submode-exit status command to check the status of the configuration.

The Split Horizon Group 2 feature allows you to prevent Broadcast, Unknown unicast and Multicast (BUM) and known unicast traffic to be flooded from one attachment circuit (AC) to other AC within the bridge domain. This feature enables efficient bandwidth allocation and resource optimization.

For more information on this feature, see the Configure Point-to-Point Layer 2 Services chapter in the L2VPN and Ethernet Services Configuration Guide for Cisco NCS 540 Series Routers.

Address-family agnostic steering uses an SR-TE policy to steer both labeled and unlabeled IPv4 and IPv6 traffic. This steering mechanism relies on color-only steering and requires support of IPv6 encapsulation (IPv6 caps) over IPV4 endpoint policy, which is enabled automatically when the policy is created in XTC. The result is that you can have a single SR-TE policy to forward traffic, regardless of the address-family.

For more information on this feature, see the Configure SR-TE Policies chapter in the Segment Routing Configuration Guide for Cisco NCS 540 Series Router.

A segment routing traffic engineering (SR-TE) policy is identified as an ordered list (head-end, color, end-point). The color-only steering feature is a traffic steering mechanism where a policy is created with a given color, regardless of the endpoint. You can create an SR-TE policy for a specific color that uses a NULL end-point (ipv4 0.0.0.0 for IPv4 NULL, and ipv6 ::0 for IPv6 NULL end-point), which minimizes the number of SR-TE policies required at a headend to forward traffic for a given address family.

You can also configure a color-only (CO) flag (co-flag 00 and co-flag 01 ) for color-only steering (NULL end-point) as part of the color extended community in BGP for overlay routes. The CO flag allows the selection of an SR-TE policy with a matching color, regardless of the endpoint.

For more information on this feature, see the Configure SR-TE Policies chapter in the Segment Routing Configuration Guide for Cisco NCS 540 Series Router.

Cisco IOS XR supports Google network management interface (gNMI) protocol in dial-in mode where the client establishes a connection to the router. gNMI is an unified mangement protocol for streaming telemetry data using OpenConfig RPC framework. This framework and protocol does not need explicit configuration, but simplifies telemetry configuration on the router by only starting the gRPC server.

In addition, support is provided for transport layer security (TLS) ciphers in gRPC session. Two new gRPC configuration parameters max-streams and max-streams-per-user are provided to stream only the gRPC-specific requests.

To enable the gRPC server in dial-in mode, see Configure Model-driven Telemetry chapter in Telemetry Configuration Guide for Cisco NCS 540 Series Routers.

This feature addresses some of the issues identified with native ACL YANG models that affect usability of the YANG model. It improves user-friendliness and standards compliance in the following ACL YANG models:

• Cisco-IOS-XR-es-acl-cfg

• Cisco-IOS-XR-ipv4-acl-cfg

• Cisco-IOS-XR-ipv6-acl-cfg

For more information about issues addressed as part of this enhancement, see Components to Use Data Models chapter of the Programmability Configuration Guide for Cisco NCS 540 Series Routers.

Before committing a configuration, the overall configuration can be validated. This helps remove conflicts when the configurations within a single commit operation are interdependent.

For information about enabling and running the command, see Bring-up the Router chapter in System Setup and Software Installation Guide for NCS 540 Series Routers, IOS XR Release 6.5.x.

The VLAN Switch feature enables you to configure L2 VLAN switching with minimum configuration. This feature allows you to configure L2 bridging without having to configure and manage separate bridge instances and sub-interfaces for each per VLAN L2 forwarding domain.

Prior to implementation of this feature, to configure and manage basic L2 bridging, numerous sub-interfaces were required. Using separate sub-interfaces for each VLAN on a port overloads the system scalability and consumes hardware resources, slows down provisioning, and makes the device harder to manage due to the large number of sub-interface constructs that exists in the system.

For more information on this feature, see the Configure Virtual LANs in Layer 2 VPNs chapter in the L2VPN and Ethernet Services Configuration Guide for Cisco NCS 540 Series Routers.