Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - High Availability on Cisco 4000 Integrated Services Routers and Cisco Catalyst 8000 Series Edge Platforms

Publisher

Cisco Systems

URL

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/ios-xe/config/ios-xe-book/m-cube-ha-isr-g3.html

Published

2026-04-25

Updated

unknown

Accessed

2026-09-25

HTTP status

200

License

Cisco copyrighted documentation; no-redistribution; short excerpts and locators only

Source notes citing this source

• Cisco advises placing an intermediate Layer 3 switch between a CUBE HA pair and an ACI fabric so ACI does not directly learn the CUBE IP and MAC addresses. in context
• CUBE box-to-box redundancy is supported on Cisco 4000 Series ISRs and Catalyst 8300, 8200 and 8200-L Edge Platforms and uses the Redundancy Group (RG) infrastructure. in context
• CUBE HA checkpoints only active calls, meaning calls connected with a completed 200 OK/ACK transaction. in context
• The documented CUBE box-to-box sequence is: configure the redundancy group with control and data interfaces, interface tracking, redundancy interfaces with RIIs and VIPs, SIP binding, redundancy-group under voice service voip, media inactivity timer, save and reload, then configure the peer and point external devices at the VIP. in context
• Support for IPv6 flows in CUBE high availability was introduced in Cisco IOS XE Dublin 17.12.1a. in context
• One CUBE of the HA pair must have the lower IP address on all three interfaces compared with the peer's corresponding interfaces. in context
• The media inactivity timer lets the HA pair disconnect calls when no RTP is received within a configured period; the example uses timer receive-rtp 1200. in context
• Media flow-around and the UC Services API are not supported with CUBE box-to-box HA. in context
• Secondary IP addresses are not permitted on CUBE HA interfaces. in context
• CUBE HA does not support co-locating Unified SRST or TDM gateway functions on the HA routers. in context
• SCCP-based media resources, CPA, noise reduction, acoustic shock protection and transrating calls are not preserved or supported across CUBE HA switchover. in context
• Out-of-band DTMF using SIP NOTIFY or KPML is not supported on a call after a CUBE HA switchover. in context
• External devices such as Unified CM must use the CUBE HA Virtual IP address, not the physical interface addresses, as the destination for calls through CUBE. in context
• Cisco recommends port channels for the RG control and data interfaces because a single cable or switch path is a single point of failure that can leave both routers Active. in context
• Prerequisites for CUBE HA include a Layer 2 connection between the active and standby routers and NTP or identical clocks on both routers. in context
• Upon a CUBE HA failover the previously active router reloads by design. in context
• After completing the CUBE HA configuration the router configuration must be saved and the router reloaded. in context
• In a CUBE HA pair the control link carries the redundancy state of each router and the data synchronization link carries stateful call and media-flow information. in context
• Cisco recommends connecting the RG control and data interfaces of the pair to the same physical switch to avoid network latency. in context
• CUBE box-to-box HA requires the same redundancy group priority and failover threshold to be configured on both routers. in context
• Configuration replicated from the active router lands only in the standby's running configuration and must be committed there with write memory. in context
• After CUBE HA failover the SIP-layer signaling state is preserved but remote user agents must re-establish TCP sessions before sending further messages. in context
• TCP, TLS and UDP transport-layer sessions are not checkpointed between the CUBE HA pair. in context
• Up to two active/standby CUBE HA pairs (two redundancy groups) may exist in the same Layer 2 segment, with a unique RII per redundant interface pair. in context
• All CUBE HA signaling and media is sourced from and sent to the Virtual IP address configured on the externally facing interfaces. in context
• VRFs must be defined identically and in the same order on both active and standby routers for accurate data synchronisation. in context

Cite this source record

APA

WarmTransfer. (2026, April 25). Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - High Availability on Cisco 4000 Integrated Services Routers and Cisco Catalyst 8000 Series Edge Platforms. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-cube-xe176-ha-isr-c8000

BibTeX

@misc{warmtransfer-cisco-cube-xe176-ha-isr-c8000,
  title  = {Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - High Availability on Cisco 4000 Integrated Services Routers and Cisco Catalyst 8000 Series Edge Platforms},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-cube-xe176-ha-isr-c8000},
  note   = {Cisco Systems, accessed 2026-09-25}
}