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Cisco Expressway clustering

Verified 2026-09-25 · 59 sources · tier 2

An Expressway cluster can contain up to 6 Expressway peers 27. Within the cluster, 1 cluster peer is nominated as the primary, and its configuration is replicated to the other peers 40.

Capacity and sizing

The X15.4 cluster deployment guide states clustering can increase Expressway capacity by a maximum factor of 4 compared with a single Expressway, and that there is no capacity gain after 4 peers 5. From X14.2, in the 4+1 redundancy model up to 5 Expressway systems can be clustered for a total capacity of 4 times a single system, with 1 node counted as redundancy 1. From X14.2, in the 5+1 redundancy model up to 6 Expressway systems can be clustered for a total capacity of 5 times a single system, with 1 node counted as redundancy; this is disputed, because another section of the guide says clustering adds no capacity beyond 4 peers 2​5.

Clustering Small VM Expressways provides redundancy only and gives no additional capacity 51. Cisco cautions that Expressway capacity figures assume single-service scenarios and that capacity limits cannot be given for individual, specific deployments 6. Regarding host sizing, 2 Large Expressway VMs can co-reside on a UCS server with two eight-core 3.2 GHz processors dedicated to Expressway when hyperthreading is enabled 22.

Expressway capacity licensing is per cluster: capacity licenses installed on any peer, including Rich Media Session (RMS) and room/desktop system registration licenses, are available to every peer 24. A call between endpoints registered to different peers uses no RMS licence if its media does not traverse the cluster peers 20.

Node and platform requirements

An Expressway cluster must contain only Expressway-C nodes or only Expressway-E nodes; the 2 cannot be mixed in 1 cluster 29. Clusters mixing Expressway and Expressway Select peers are also not supported 32. All peers in an Expressway cluster must run the same software version, except for the short period while the cluster is being upgraded 48.

Peers on standard appliances can be clustered with peers on 2-core Medium VMs, but not with peers on 8-core Large VMs 3. All cluster peers must have the same set of option keys installed, except RMS licenses and room system and desktop system registration licenses 35. Every peer in an Expressway cluster must have the same routing capabilities, because the cluster assumes any peer can route to any destination another peer can reach 47.

Network and inter-peer communication

Expressway clustering supports a round-trip delay of up to 80 ms between peers 46. There must be no NAT between Expressway cluster peers, and any firewall between them must open the required ports 30. WarmTransfer's reading of the sources is that because peers must be within 80 ms round trip with no NAT between them, a single Expressway cluster can only span sites with low-latency routed connectivity, and widely separated regions would need separate clusters 17.

From X8.8, cluster peers use TCP 4371 for cluster recovery and TLS on TCP 4372 for cluster communication and database synchronization 37. Before X8.8, Expressway clustering used IPsec (AH and ISAKMP on UDP 500) between peers rather than TLS 38. H.323 mode must be on for each Expressway cluster peer because clustering uses H.323 communication between peers; if it is off, an Invalid clustering configuration alarm is raised 19.

DNS and endpoint interaction

Cisco recommends a DNS SRV record for the Expressway cluster containing A or AAAA records for each peer 14. For Mobile and Remote Access, a collab-edge SRV record should be created for each peer in the Expressway-E cluster 28.

An H.323 endpoint registering to 1 peer receives a list of alternate gatekeepers containing the IP addresses of all other cluster peers in random order 18. SIP endpoints that support RFC 5626 can register simultaneously to multiple Expressway cluster peers 50. In addition, cluster peers share bandwidth usage information, so bandwidth consumed in a subzone or pipe by 1 peer is unavailable to the other peers 4.

If Cisco TMS is used with an Expressway cluster it must run version 13.2 or later, or 12.6 or later if TMS is not used for provisioning or FindMe 55.

Cluster formation and configuration replication

To form a cluster, an administrator first creates a cluster of 1 (the primary) and restarts it before adding other peers 10. The Expressway cluster name should be the routable FQDN used in the SRV records that address the cluster, and the same cluster name must be configured on every peer 9.

Cluster TLS verification mode defaults to Permissive; Enforce requires valid peer certificates 54. All peers in an Expressway cluster must use the same TLS verification mode 53. Cisco recommends forming the cluster with IP addresses in Permissive mode, then changing peer addresses to FQDNs, and then switching TLS verification mode to Enforce 16.

Configuration changes made on a peer other than the primary are not replicated and will be overwritten at the next replication from the primary 52. DNS server settings are peer-specific and are not replicated; each peer can use a different set of DNS servers 13. NTP servers are peer-specific, and each peer may use 1 or more different NTP servers 33. Trusted CA certificates, the server certificate, and CRLs must be uploaded to each Expressway peer individually; they are not replicated 7. Conference Factory template configuration is not replicated across Expressway cluster peers; Cisco documents this as expected behaviour 11.

Maintenance, cluster changes, and troubleshooting

To remove a live peer, an administrator clears all Peer N address fields on it, saves, and restarts, which factory-resets it; the primary and remaining peers then need identical, gap-free peer lists 41. If a removed dead peer is later recovered, its configuration must be cleared before it is reconnected to the network 12. Changing a clustered peer's IP address, hostname, or FQDN requires removing it from the cluster, making the change, and adding it back 8. Furthermore, a backup cannot be restored to an Expressway while it is part of a cluster; it must first be removed from the cluster 45.

When upgrading an Expressway cluster, upgrade the primary peer first and then the subordinate peers 1 at a time 58. Cisco recommends upgrading the Expressway-E cluster before the Expressway-C cluster, starting with the primary peer in each 56. While a cluster is mid-upgrade, configuration changes are not replicated to subordinate peers running a different version from the primary 31. The X15.4 cluster deployment guide defers cluster upgrade instructions to the release notes for the target version 57. Cisco TAC's X14.x upgrade note advises confirming no cluster alarms exist and taking a backup of each server before upgrading 39.

In a cluster, a peer in maintenance mode has its workload handled by the other peers, and Cisco advises enabling maintenance mode on only 1 peer at a time in large deployments 26.

Cluster replication health is checked at System > Clustering on each peer, where the cluster database status should read Active 43. For the alarm requiring manual synchronization of configuration, Cisco directs running xcommand ForceConfigUpdate as admin on the subordinate, which deletes its configuration and forces an update from the primary; back up first 15. The documented cluster restart sequence is to restart the primary, wait until its web interface is reachable and replication is healthy, then restart the other peers 1 at a time 44. A cluster replication error can also be raised because the NTP server is unreachable; the fix is to configure an accessible NTP server on System > Time 34.

See also

See also Expressway and Mobile and Remote Access. See also Setting up Mobile and Remote Access on Cisco Expressway.

Applicability

Applies to: Cisco Expressway. Deployments: on-premises. Sources checked 2026-09-25. As of 2026-09-25, Cisco's Expressway release-notes listing includes an X15.5.x release note above X15.4.x, whose release note is dated April 13, 2026 23.

What remains uncertain

The following items are not covered by the sources below:

  • X15.5 release note clustering and upgrade content is not covered by the sources below.
  • How to reconcile the 4x capacity gain limit with the 5+1 redundancy model scaling statement is not covered by the sources below.
  • Client Auth EKU sunset in public CA certs and its interaction with cluster TLS Enforce mode is not covered by the sources below.
  • MRA deployment guide guidance on cluster DNS and configuring traversal zones to multiple Expressway-E peers is not covered by the sources below.
  • Cisco Smart Licensing behaviour for pooled RMS licences across cluster peers is not covered by the sources below.
  • Numeric alarm IDs for cluster alarms are not covered by the sources below.
  • The CE1300 hardware platform MRA registration capacity figure is not covered by the sources below.
  • Certificate Subject Alternative Name (SAN) requirements for cluster TLS Enforce mode are not covered by the sources below.

See also

Related to

  • Unified CM security hardening — Cluster TLS verification mode (Permissive vs Enforce) and firewall filtering of clustering ports 4371/4372 are hardening concerns; proposed by this packet; not previously recorded.
  • Unified CM virtualization and sizing — Expressway VM sizes (Small/Medium/Large) and co-residency rules constrain which peers may be clustered and what capacity a cluster yields; proposed by this packet; not previously recorded.

Referenced by

Sources

  1. 1
    From X14.2, in the 4+1 redundancy model up to five Expressway systems can be clustered for a total capacity of four times a single system, with one node counted as redundancy.
    Cisco Expressway Administrator Guide (X15.4) - Expressway Capacity and Sizing · Expressway Capacity and Sizing chapter, Important Caveats, 4+1 redundancy model sentence · Checked 2026-09-25
  2. 2
    From X14.2, in the 5+1 redundancy model up to six Expressway systems can be clustered for a total capacity of five times a single system, with one node counted as redundancy.
    Cisco Expressway Administrator Guide (X15.4) - Expressway Capacity and Sizing · Expressway Capacity and Sizing chapter, Important Caveats, 5+1 redundancy model sentence · Checked 2026-09-25
  3. 3
    Peers on standard appliances can be clustered with peers on 2-core Medium VMs, but not with peers on 8-core Large VMs.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, Platform and Software Versions Match · Checked 2026-09-25
  4. 4
    Cluster peers share bandwidth usage information, so bandwidth consumed in a subzone or pipe by one peer is unavailable to the other peers.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, bandwidth sharing section · Checked 2026-09-25
  5. 5
    The X15.4 cluster deployment guide states clustering can increase Expressway capacity by a maximum factor of four compared with a single Expressway and that there is no capacity gain after four peers.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Basics · Clustering Basics chapter, overview of reasons to cluster (capacity) · Checked 2026-09-25
  6. 6
    Cisco cautions that Expressway capacity figures assume single-service scenarios and that capacity limits cannot be given for individual, specific deployments.
    Cisco Expressway Administrator Guide (X15.4) - Expressway Capacity and Sizing · Expressway Capacity and Sizing chapter, Important Caveats · Checked 2026-09-25
  7. 7
    Trusted CA certificates, the server certificate and CRLs must be uploaded to each Expressway peer individually; they are not replicated.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, Peer-Specific Items in Clustered Systems (security certificates) · Checked 2026-09-25
  8. 8
    Changing a clustered peer's IP address, hostname or FQDN requires removing it from the cluster, making the change, and adding it back.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Change a Cluster · How to Change a Cluster chapter, change peer IP address or identity · Checked 2026-09-25
  9. 9
    The Expressway cluster name should be the routable FQDN used in the SRV records that address the cluster, and the same cluster name must be configured on every peer.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Form a Cluster · How to Form a Cluster chapter, cluster name field · Checked 2026-09-25
  10. 10
    To form a cluster you first create a cluster of one (the primary) and restart it before adding other peers.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Form a Cluster · How to Form a Cluster chapter, primary peer set-up · Checked 2026-09-25
  11. 11
    Conference Factory template configuration is not replicated across Expressway cluster peers; Cisco documents this as expected behaviour.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Troubleshooting · Troubleshooting chapter, Conference Factory Template Does Not Replicate · Checked 2026-09-25
  12. 12
    If a removed dead peer is later recovered, its configuration must be cleared before it is reconnected to the network.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Change a Cluster · How to Change a Cluster chapter, Remove a Dead Peer · Checked 2026-09-25
  13. 13
    DNS server settings are peer-specific and are not replicated; each peer can use a different set of DNS servers.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, Peer-Specific Items in Clustered Systems (DNS servers) · Checked 2026-09-25
  14. 15
    For the alarm requiring manual synchronization of configuration, Cisco directs running xcommand ForceConfigUpdate as admin on the subordinate, which deletes its configuration and forces an update from the primary; back up first.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Troubleshooting · Troubleshooting chapter, Cluster replication error: manual synchronization of configuration is required · Checked 2026-09-25
  15. 16
    Cisco recommends forming the cluster with IP addresses in Permissive mode, then changing peer addresses to FQDNs, and then switching TLS verification mode to Enforce.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Form a Cluster · How to Form a Cluster chapter, TLS verification mode guidance · Checked 2026-09-25
  16. 17
    Because peers must be within 80 ms round trip with no NAT between them, a single Expressway cluster can only span sites with low-latency routed connectivity; widely separated regions would need separate clusters.inferred
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, Network Conditions Are Met · Checked 2026-09-25
  17. 18
    An H.323 endpoint registering to one peer receives a list of alternate gatekeepers containing the IP addresses of all other cluster peers in random order.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, H.323 registrations · Checked 2026-09-25
  18. 19
    H.323 mode must be on for each Expressway cluster peer because clustering uses H.323 communication between peers; if it is off, an Invalid clustering configuration alarm is raised.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Troubleshooting · Troubleshooting chapter, Invalid clustering configuration: H.323 mode · Checked 2026-09-25
  19. 20
    A call between endpoints registered to different peers uses no RMS licence if its media does not traverse the cluster peers.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, Intracluster Calls · Checked 2026-09-25
  20. 21
    In X15.x a standalone Large VM Expressway is rated for 5,000 native registrations, 500 video or 1,000 audio calls, and 3,500 MRA registrations.
    Cisco Expressway Administrator Guide (X15.4) - Expressway Capacity and Sizing · Expressway Capacity and Sizing chapter, standalone capacity table, Large VM row · Checked 2026-09-25
  21. 22
    Two Large Expressway VMs can co-reside on a UCS server with two eight-core 3.2 GHz processors dedicated to Expressway when hyperthreading is enabled.
    Cisco Expressway Install and Upgrade Guide (X15.4) - Requirements and Limitations · Requirements and Limitations chapter, ESXi Requirements, co-residency note · Checked 2026-09-25
  22. 23
    As of 2026-09-25 Cisco's Expressway release-notes listing includes an X15.5.x release note above X15.4.x, whose release note is dated April 13, 2026.
    Cisco Expressway Series - Release Notes · Release Notes listing, X15.5.x and X15.4.x entries · Checked 2026-09-25
  23. 24
    Expressway capacity licensing is per cluster: capacity licenses installed on any peer, including Rich Media Session and room/desktop system registration licenses, are available to every peer.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Basics · Clustering Basics chapter, licensing statement · Checked 2026-09-25
  24. 25
    In maintenance mode, existing calls on the peer continue until they end, while new calls and registrations go to other peers.
    Cisco Expressway Administrator Guide (X15.4) - Maintenance · Maintenance chapter, Enable Maintenance Mode · Checked 2026-09-25
  25. 26
    In a cluster, a peer in maintenance mode has its workload handled by the other peers, and Cisco advises enabling maintenance mode on only one peer at a time in large deployments.
    Cisco Expressway Administrator Guide (X15.4) - Maintenance · Maintenance chapter, Enable Maintenance Mode · Checked 2026-09-25
  26. 27
    An Expressway cluster can contain up to six Expressway peers.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Basics · Clustering Basics chapter, opening overview section · Checked 2026-09-25
  27. 28
    For Mobile and Remote Access, a collab-edge SRV record should be created for each peer in the Expressway-E cluster.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, DNS Configuration Is Done, MRA item · Checked 2026-09-25
  28. 29
    An Expressway cluster must contain only Expressway-C nodes or only Expressway-E nodes; the two cannot be mixed in one cluster.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, deployment restrictions · Checked 2026-09-25
  29. 30
    There must be no NAT between Expressway cluster peers, and any firewall between them must open the required ports.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, Network Conditions Are Met · Checked 2026-09-25
  30. 31
    While a cluster is mid-upgrade, configuration changes are not replicated to subordinate peers running a different version from the primary.
    Cisco Expressway Administrator Guide (X15.4) - Maintenance · Maintenance chapter, Process to Upgrade a Clustered System · Checked 2026-09-25
  31. 32
    Clusters mixing Expressway and Expressway Select peers are not supported.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, deployment restrictions · Checked 2026-09-25
  32. 33
    NTP servers are peer-specific; each peer may use one or more different NTP servers.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, Peer-Specific Items in Clustered Systems (NTP servers) · Checked 2026-09-25
  33. 34
    A cluster replication error can be raised because the NTP server is unreachable; the fix is to configure an accessible NTP server on System > Time.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Troubleshooting · Troubleshooting chapter, Cluster replication error: NTP server unreachable · Checked 2026-09-25
  34. 35
    All cluster peers must have the same set of option keys installed, except RMS licenses and room system and desktop system registration licenses.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, Basic Configuration Is Done · Checked 2026-09-25
  35. 36
    If a replication error persists after ForceConfigUpdate, Cisco advises upgrading the primary again with the original upgrade package; the alarm typically clears 10 to 20 minutes after reboot.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Troubleshooting · Troubleshooting chapter, replication error persisting after ForceConfigUpdate · Checked 2026-09-25
  36. 37
    From X8.8, cluster peers use TCP 4371 for cluster recovery and TLS on TCP 4372 for cluster communication and database synchronization.
    Cisco Expressway IP Port Usage Configuration Guide (Includes X14.3 and X15.0 releases) - Clustering Connections · Clustering Connections chapter, Table 2 (cluster database synchronization) · Checked 2026-09-25
  37. 38
    Before X8.8, Expressway clustering used IPsec (AH and ISAKMP on UDP 500) between peers rather than TLS.
    Cisco Expressway IP Port Usage Configuration Guide (Includes X14.3 and X15.0 releases) - Clustering Connections · Clustering Connections chapter, Cluster Connections Before X8.8 · Checked 2026-09-25
  38. 39
    Cisco TAC's X14.x upgrade note advises confirming no cluster alarms exist and taking a backup of each server before upgrading.
    Upgrade Video Communication Server (VCS) / Expressway X14.x · Pre-upgrade requirements section (cluster stability check; backup) · Checked 2026-09-25
  39. 40
    One cluster peer is nominated as the primary, and its configuration is replicated to the other peers.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Basics · Clustering Basics chapter, overview · Checked 2026-09-25
  40. 41
    To remove a live peer you clear all Peer N address fields on it, save and restart, which factory-resets it; the primary and remaining peers then need identical, gap-free peer lists.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Change a Cluster · How to Change a Cluster chapter, Remove a Live Peer · Checked 2026-09-25
  41. 42
    Configuration is copied from the primary to the other peers about every two minutes, and changes can take up to about a minute to appear on all peers.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Form a Cluster · How to Form a Cluster chapter, post-restart verification steps · Checked 2026-09-25
  42. 43
    Cluster replication health is checked at System > Clustering on each peer, where the cluster database status should read Active.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Troubleshooting · Troubleshooting chapter, Check Replication Status · Checked 2026-09-25
  43. 44
    The documented cluster restart sequence is to restart the primary, wait until its web interface is reachable and replication is healthy, then restart the other peers one at a time.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Troubleshooting · Troubleshooting chapter, Restarting Sequence · Checked 2026-09-25
  44. 45
    A backup cannot be restored to an Expressway while it is part of a cluster; it must first be removed from the cluster.
    Cisco Expressway Administrator Guide (X15.4) - Maintenance · Maintenance chapter, Restoring a Previous Backup · Checked 2026-09-25
  45. 46
    Expressway clustering supports a round-trip delay of up to 80 ms between peers.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, Network Conditions Are Met · Checked 2026-09-25
  46. 47
    Every peer in an Expressway cluster must have the same routing capabilities, because the cluster assumes any peer can route to any destination another peer can reach.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Basics · Clustering Basics chapter, routing statement · Checked 2026-09-25
  47. 48
    All peers in an Expressway cluster must run the same software version, except for the short period while the cluster is being upgraded.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, Platform and Software Versions Match · Checked 2026-09-25
  48. 49
    Cisco's X15.4 documentation is internally inconsistent on the maximum capacity multiplier of an Expressway cluster: the cluster deployment guide says four times with no gain after four peers, while the Administrator Guide capacity chapter describes a 5+1 model yielding five times.disputed
    Cisco Expressway Administrator Guide (X15.4) - Expressway Capacity and Sizing · Expressway Capacity and Sizing chapter, Important Caveats; compare Cluster Creation and Maintenance Deployment Guide X15.4, Clustering Basics · Checked 2026-09-25
  49. 50
    SIP endpoints that support RFC 5626 can register simultaneously to multiple Expressway cluster peers.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, SIP registrations · Checked 2026-09-25
  50. 51
    Clustering Small VM Expressways provides redundancy only and gives no additional capacity.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Basics · Clustering Basics chapter, Small VM note · Checked 2026-09-25
  51. 52
    Configuration changes made on a peer other than the primary are not replicated and will be overwritten at the next replication from the primary.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, Other Configuration for the Cluster · Checked 2026-09-25
  52. 53
    All peers in an Expressway cluster must use the same TLS verification mode.
    Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers · Clustering and Peers chapter, Basics of Cluster Configuration · Checked 2026-09-25
  53. 54
    Cluster TLS verification mode defaults to Permissive; Enforce requires valid peer certificates.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Form a Cluster · How to Form a Cluster chapter, TLS verification mode field · Checked 2026-09-25
  54. 55
    If Cisco TMS is used with an Expressway cluster it must run version 13.2 or later, or 12.6 or later if TMS is not used for provisioning or FindMe.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements · Clustering Requirements chapter, TMS Is Configured (When Essential) · Checked 2026-09-25
  55. 56
    Cisco recommends upgrading the Expressway-E cluster before the Expressway-C cluster, starting with the primary peer in each.
    Cisco Expressway Administrator Guide (X15.4) - Maintenance · Maintenance chapter, Process to Upgrade a Clustered System · Checked 2026-09-25
  56. 57
    The X15.4 cluster deployment guide defers cluster upgrade instructions to the release notes for the target version.
    Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Change a Cluster · How to Change a Cluster chapter, upgrading a cluster note · Checked 2026-09-25
  57. 58
    When upgrading an Expressway cluster, upgrade the primary peer first and then the subordinate peers one at a time.
    Cisco Expressway Administrator Guide (X15.4) - Maintenance · Maintenance chapter, Process to Upgrade a Clustered System · Checked 2026-09-25
  58. 59
    Expressway Small and Medium VMs use 2 vCPU and the Large VM uses 8 vCPU, which is why Large VMs are the 8-core peers that cannot be clustered with standard appliances.inferred
    Virtualization for Cisco Expressway · VM configuration table, Small/Medium/Large rows · Checked 2026-09-25

Documents

tier 2 current vendor documentation

Cisco Expressway Administrator Guide (X15.4) - Clustering and Peers

Cisco Systems · 2026-02-09 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Administrator Guide (X15.4) - Expressway Capacity and Sizing

Cisco Systems · 2026-02-09 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Administrator Guide (X15.4) - Maintenance

Cisco Systems · 2026-02-09 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Basics

Cisco Systems · 2026-02-09 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Clustering Requirements

Cisco Systems · 2026-02-09 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Change a Cluster

Cisco Systems · 2026-02-09 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - How to Form a Cluster

Cisco Systems · 2026-02-09 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X15.4) - Troubleshooting

Cisco Systems · 2026-02-09 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Install and Upgrade Guide (X15.4) - Requirements and Limitations

Cisco Systems · 2026-04-03 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway IP Port Usage Configuration Guide (Includes X14.3 and X15.0 releases) - Clustering Connections

Cisco Systems · 2024-01-11 · accessed 2026-09-25

tier 2 current vendor documentation

Cisco Expressway Series - Release Notes

Cisco Systems · accessed 2026-09-24

tier 2 current vendor documentation

Upgrade Video Communication Server (VCS) / Expressway X14.x

Cisco Systems (TAC) · 2024-04-05 · accessed 2026-09-25

tier 2 current vendor documentation

Virtualization for Cisco Expressway

Cisco Systems · 2026-09-25 · accessed 2026-09-25

Cite this page

APA

WarmTransfer. (2026, September 25). Cisco Expressway clustering. WarmTransfer. https://warmtransfer.net/knowledge/expressway-clustering

BibTeX

@misc{warmtransfer-expressway-clustering,
  title  = {Cisco Expressway clustering},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/expressway-clustering},
  note   = {Verified 2026-09-25}
}