Deploy a Cluster for Firepower Threat Defense

About Clustering on the Firepower 4100/9300 Chassis

Performance Scaling Factor

Bootstrap Configuration

Cluster Members

Primary and Secondary Unit Roles

Primary Unit Election

Cluster Control Link

Size the Cluster Control Link for Inter-Chassis Clustering

Cluster Control Link Redundancy for Inter-Chassis Clustering

Cluster Control Link Reliability for Inter-Chassis Clustering

Cluster Control Link Network

Management Network

Management Interface

Cluster Interfaces

Spanned EtherChannels

Connecting to a VSS or vPC

High Availability Within the Cluster

Chassis-Application Monitoring

Unit Health Monitoring

Interface Monitoring

Decorator Application Monitoring

Status After Failure

Rejoining the Cluster

Data Path Connection State Replication

Configuration Replication

How the Cluster Manages Connections

Connection Roles

New Connection Ownership

Sample Data Flow

Firepower Threat Defense Features and Clustering

Unsupported Features with Clustering

Centralized Features for Clustering

Dynamic Routing and Clustering

NAT and Clustering

SIP Inspection and Clustering

Syslog and Clustering

SNMP and Clustering

FTP and Clustering

Cisco TrustSec and Clustering

Prerequisites for Clustering

Guidelines for Clustering

Defaults for Clustering on the Firepower 4100/9300 Chassis

Configure Clustering on the Firepower 4100/9300 Chassis

Deploy the Cluster from the FXOS Chassis Supervisor

Add a Cluster to the Management Center

Add a Cluster Member

Delete a Secondary Member

Rejoin the Cluster

History for Clustering

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Deploy a Cluster for Firepower Threat Defense

Clustering lets you group multiple Firepower Threat Defense units together as a single logical device. Clustering is only supported for the Firepower Threat Defense device on the Firepower 9300 and the Firepower 4100 series. A cluster provides all the convenience of a single device (management, integration into a network) while achieving the increased throughput and redundancy of multiple devices.

Note

Some features are not supported when using clustering. See Unsupported Features with Clustering.

About Clustering on the Firepower 4100/9300 Chassis

The cluster consists of multiple devices acting as a single logical unit. When you deploy a cluster on the Firepower 4100/9300 chassis, it does the following:

- Creates a cluster-control link (by default, port-channel 48) for unit-to-unit communication. For intra-chassis clustering (Firepower 9300 only), this link utilizes the Firepower 9300 backplane for cluster communications. For inter-chassis clustering, you need to manually assign physical interface(s) to this EtherChannel for communications between chassis.

- Creates the cluster bootstrap configuration within the application.

When you deploy the cluster, the Firepower 4100/9300 chassis supervisor pushes a minimal bootstrap configuration to each unit that includes the cluster name, cluster control link interface, and other cluster settings.

- Assigns data interfaces to the cluster as Spanned interfaces.

For intra-chassis clustering, spanned interfaces are not limited to EtherChannels, like it is for inter-chassis clustering.The Firepower 9300 supervisor uses EtherChannel technology internally to load-balance traffic to multiple modules on a shared interface, so any data interface type works for Spanned mode. For inter-chassis clustering, you must use Spanned EtherChannels for all data interfaces.

Note

Individual interfaces are not supported, with the exception of a management interface.

- Assigns a management interface to all units in the cluster.

The following sections provide more detail about clustering concepts and implementation.

Performance Scaling Factor

When you combine multiple units into a cluster, you can expect the total cluster performance to be approximately:

- TCP or CPS throughput—0.8 x number_of_units

- UDP throughput—0.9 x number_of_units

- Ethernet MIX (EMIX) throughput—0.6 x number_of_units, depending on the traffic mix

Bootstrap Configuration

When you deploy the cluster, the Firepower 4100/9300 chassis supervisor pushes a minimal bootstrap configuration to each unit that includes the cluster name, cluster control link interface, and other cluster settings.

Cluster Members

Cluster members work together to accomplish the sharing of the security policy and traffic flows. This section describes the nature of each member role.

Primary and Secondary Unit Roles

One member of the cluster is the primary unit. The primary unit is determined automatically. All other members are secondary units.

You must perform all configuration on the primary unit only; the configuration is then replicated to the secondary units.

Some features do not scale in a cluster, and the primary unit handles all traffic for those features. See Centralized Features for Clustering.

Primary Unit Election

Members of the cluster communicate over the cluster control link to elect a primary unit as follows:

1. When you deploy the cluster, each unit broadcasts an election request every 3 seconds.

2. Any other units with a higher priority respond to the election request; the priority is set when you deploy the cluster and is not configurable.

3. If after 45 seconds, a unit does not receive a response from another unit with a higher priority, then it becomes primary.

4. If a unit later joins the cluster with a higher priority, it does not automatically become the primary unit; the existing primary unit always remains as the primary unless it stops responding, at which point a new primary unit is elected.

Note

You can manually force a unit to become the primary. For centralized features, if you force a primary unit change, then all connections are dropped, and you have to re-establish the connections on the new primary unit.

Cluster Control Link

The cluster control link is automatically created using the Port-channel 48 interface. For intra-chassis clustering, this interface has no member interfaces. For inter-chassis clustering, you must add one or more interfaces to the EtherChannel. This Cluster type EtherChannel utilizes the Firepower 9300 backplane for cluster communications for intra-chassis clustering.

For a 2-member inter-chassis cluster, do not directly connect the cluster control link from one chassis to the other chassis. If you directly connect the interfaces, then when one unit fails, the cluster control link fails, and thus the remaining healthy unit fails. If you connect the cluster control link through a switch, then the cluster control link remains up for the healthy unit.

Cluster control link traffic includes both control and data traffic.

Size the Cluster Control Link for Inter-Chassis Clustering

If possible, you should size the cluster control link to match the expected throughput of each chassis so the cluster-control link can handle the worst-case scenarios.

Cluster control link traffic is comprised mainly of state update and forwarded packets. The amount of traffic at any given time on the cluster control link varies. The amount of forwarded traffic depends on the load-balancing efficacy or whether there is a lot of traffic for centralized features. For example:

- NAT results in poor load balancing of connections, and the need to rebalance all returning traffic to the correct units.

- When membership changes, the cluster needs to rebalance a large number of connections, thus temporarily using a large amount of cluster control link bandwidth.

A higher-bandwidth cluster control link helps the cluster to converge faster when there are membership changes and prevents throughput bottlenecks.

Note

If your cluster has large amounts of asymmetric (rebalanced) traffic, then you should increase the cluster control link size.

Cluster Control Link Redundancy for Inter-Chassis Clustering

The following diagram shows how to use an EtherChannel as a cluster control link in a Virtual Switching System (VSS) or Virtual Port Channel (vPC) environment. All links in the EtherChannel are active. When the switch is part of a VSS or vPC, then you can connect Firepower 4100/9300 chassis interfaces within the same EtherChannel to separate switches in the VSS or vPC. The switch interfaces are members of the same EtherChannel port-channel interface, because the separate switches act like a single switch. Note that this EtherChannel is device-local, not a Spanned EtherChannel.

Cluster Control Link Reliability for Inter-Chassis Clustering

To ensure cluster control link functionality, be sure the round-trip time (RTT) between units is less than 20 ms. This maximum latency enhances compatibility with cluster members installed at different geographical sites. To check your latency, perform a ping on the cluster control link between units.

The cluster control link must be reliable, with no out-of-order or dropped packets; for example, for inter-site deployment, you should use a dedicated link.

Cluster Control Link Network

The Firepower 4100/9300 chassis auto-generates the cluster control link interface IP address for each unit based on the chassis ID and slot ID: 127.2.chassis_id.slot_id. You cannot set this IP address manually, either in FXOS or within the application. The cluster control link network cannot include any routers between units; only Layer 2 switching is allowed.

Management Network

We recommend connecting all units to a single management network. This network is separate from the cluster control link.

Management Interface

You must assign a Management type interface to the cluster. This interface is a special individual interface as opposed to a Spanned interface. The management interface lets you connect directly to each unit. This Management logical interface is separate from the other interfaces on the device. It is used to set up and register the device to the Firepower Management Center. It uses its own local authentication, IP address, and static routing. Each cluster member uses a separate IP address on the management network that you set as part of the bootstrap configuration.

The management interface is shared between the Management logical interface and the Diagnostic logical interface. The Diagnostic logical interface is optional and is not configured as part of the bootstrap configuration. The Diagnostic interface can be configured along with the rest of the data interfaces. If you choose to configure the Diagnostic interface, configure a Main cluster IP address as a fixed address for the cluster that always belongs to the current primary unit. You also configure a range of addresses so that each unit, including the current primary, can use a Local address from the range. The Main cluster IP address provides consistent diagnostic access to an address; when a primary unit changes, the Main cluster IP address moves to the new primary unit, so access to the cluster continues seamlessly. For outbound management traffic such as TFTP or syslog, each unit, including the primary unit, uses the Local IP address to connect to the server.

Cluster Interfaces

For intra-chassis clustering, you can assign both physical interfaces or EtherChannels (also known as port channels) to the cluster. Interfaces assigned to the cluster are Spanned interfaces that load-balance traffic across all members of the cluster.

For inter-chassis clustering, you can only assign data EtherChannels to the cluster. These Spanned EtherChannels include the same member interfaces on each chassis; on the upstream switch, all of these interfaces are included in a single EtherChannel, so the switch does not know that it is connected to multiple devices.

Individual interfaces are not supported, with the exception of a management interface.

Spanned EtherChannels

You can group one or more interfaces per chassis into an EtherChannel that spans all chassis in the cluster. The EtherChannel aggregates the traffic across all the available active interfaces in the channel. A Spanned EtherChannel can be configured in both routed and transparent firewall modes. In routed mode, the EtherChannel is configured as a routed interface with a single IP address. In transparent mode, the IP address is assigned to the BVI, not to the bridge group member interface. The EtherChannel inherently provides load balancing as part of basic operation.

Connecting to a VSS or vPC

We recommend connecting EtherChannels to a VSS or vPC to provide redundancy for your interfaces.

High Availability Within the Cluster

Clustering provides high availability by monitoring chassis, unit, and interface health and by replicating connection states between units.

Chassis-Application Monitoring

Chassis-application health monitoring is always enabled. The Firepower 4100/9300 chassis supervisor checks the Firepower Threat Defense application periodically (every second). If the Firepower Threat Defense device is up and cannot communicate with the Firepower 4100/9300 chassis supervisor for 3 seconds, the Firepower Threat Defense device generates a syslog message and leaves the cluster.

If the Firepower 4100/9300 chassis supervisor cannot communicate with the application after 45 seconds, it reloads the Firepower Threat Defense device. If the Firepower Threat Defense device cannot communicate with the supervisor, it removes itself from the cluster.

Unit Health Monitoring

The primary unit monitors every secondary unit by sending keepalive messages over the cluster control link periodically. Each secondary unit monitors the primary unit using the same mechanism. If the unit health check fails, the unit is removed from the cluster.

Interface Monitoring

Each unit monitors the link status of all hardware interfaces in use, and reports status changes to the primary unit. For inter-chassis clustering, Spanned EtherChannels use the cluster Link Aggregation Control Protocol (cLACP). Each chassis monitors the link status and the cLACP protocol messages to determine if the port is still active in the EtherChannel, and informs the Firepower Threat Defense application if the interface is down. When you enable health monitoring, all physical interfaces are monitored by default (including the main EtherChannel for EtherChannel interfaces). Only named interfaces that are in an Up state can be monitored. For example, all member ports of an EtherChannel must fail before a named EtherChannel is removed from the cluster.

If a monitored interface fails on a particular unit, but it is active on other units, then the unit is removed from the cluster. The amount of time before the Firepower Threat Defense device removes a member from the cluster depends on whether the unit is an established member or is joining the cluster. The Firepower Threat Defense device does not monitor interfaces for the first 90 seconds that a unit joins the cluster. Interface status changes during this time will not cause the Firepower Threat Defense device to be removed from the cluster. For an established member, the unit is removed after 500 ms.

For inter-chassis clustering, if you add or delete an EtherChannel from the cluster, interface health-monitoring is suspended for 95 seconds to ensure that you have time to make the changes on each chassis.

Decorator Application Monitoring

When you install a decorator application on an interface, such as the Radware DefensePro application, then both the Firepower Threat Defense device and the decorator application must be operational to remain in the cluster. The unit does not join the cluster until both applications are operational. Once in the cluster, the unit monitors the decorator application health every 3 seconds. If the decorator application is down, the unit is removed from the cluster.

Status After Failure

When a unit in the cluster fails, the connections hosted by that unit are seamlessly transferred to other units; state information for traffic flows is shared over the control cluster link.

If the primary unit fails, then another member of the cluster with the highest priority (lowest number) becomes the primary unit.

The Firepower Threat Defense device automatically tries to rejoin the cluster, depending on the failure event.

Note

When the Firepower Threat Defense device becomes inactive and fails to automatically rejoin the cluster, all data interfaces are shut down; only the Management/Diagnostic interface can send and receive traffic.

Rejoining the Cluster

After a cluster member is removed from the cluster, how it can rejoin the cluster depends on why it was removed:

- Failed cluster control link—After you resolve the problem with the cluster control link, you must manually rejoin the cluster by re-enabling clustering.

- Failed data interface—The Firepower Threat Defense application automatically tries to rejoin at 5 minutes, then at 10 minutes, and finally at 20 minutes. If the join is not successful after 20 minutes, then the Firepower Threat Defense application disables clustering. After you resolve the problem with the data interface, you have to manually enable clustering.

- Failed unit—If the unit was removed from the cluster because of a unit health check failure, then rejoining the cluster depends on the source of the failure. For example, a temporary power failure means the unit will rejoin the cluster when it starts up again as long as the cluster control link is up. The Firepower Threat Defense application attempts to rejoin the cluster every 5 seconds.

- Failed Chassis-Application Communication—When the Firepower Threat Defense application detects that the chassis-application health has recovered, it tries to rejoin the cluster automatically.

Data Path Connection State Replication

Every connection has one owner and at least one backup owner in the cluster. The backup owner does not take over the connection in the event of a failure; instead, it stores TCP/UDP state information, so that the connection can be seamlessly transferred to a new owner in case of a failure.

If the owner becomes unavailable, the first unit to receive packets from the connection (based on load balancing) contacts the backup owner for the relevant state information so it can become the new owner.

Some traffic requires state information above the TCP or UDP layer. See the following table for clustering support or lack of support for this kind of traffic.

Features Replicated Across the Cluster

Traffic

State Support

Notes

Up time

Yes

Keeps track of the system up time.

ARP Table

Yes

—

MAC address table

Yes

—

User Identity

Yes

—

IPv6 Neighbor database

Yes

—

Dynamic routing

Yes

—

SNMP Engine ID

No

—

Centralized VPN (Site-to-Site)

No

VPN sessions will be disconnected if the primary unit fails.

Configuration Replication

All units in the cluster share a single configuration. You can only make configuration changes on the primary unit, and changes are automatically synced to all other units in the cluster.

How the Cluster Manages Connections

Connections can be load-balanced to multiple members of the cluster. Connection roles determine how connections are handled in both normal operation and in a high availability situation.

Connection Roles

There are 3 different roles defined for each connection:

- Owner—The unit that initially receives the connection. The owner maintains the TCP state and processes packets. A connection has only one owner. If the original owner fails, then when new units receive packets from the connection, the director chooses a new owner from those units.

- Director—The unit that handles owner lookup requests from forwarders and also maintains the connection state to serve as a backup if the owner fails. When the owner receives a new connection, it chooses a director based on a hash of the source/destination IP address and TCP ports, and sends a message to the director to register the new connection. If packets arrive at any unit other than the owner, the unit queries the director about which unit is the owner so it can forward the packets. A connection has only one director. If a director fails, the owner chooses a new director.

- Forwarder—A unit that forwards packets to the owner. If a forwarder receives a packet for a connection it does not own, it queries the director for the owner, and then establishes a flow to the owner for any other packets it receives for this connection. The director can also be a forwarder. Note that if a forwarder receives the SYN-ACK packet, it can derive the owner directly from a SYN cookie in the packet, so it does not need to query the director. (If you disable TCP sequence randomization, the SYN cookie is not used; a query to the director is required.) For short-lived flows such as DNS and ICMP, instead of querying, the forwarder immediately sends the packet to the director, which then sends them to the owner. A connection can have multiple forwarders; the most efficient throughput is achieved by a good load-balancing method where there are no forwarders and all packets of a connection are received by the owner.

For inter-chassis clustering, if the director for a flow is in the same chassis as the owner, then an additional director is chosen on a different chassis to act as the director's backup in case the owner's chassis fails. If the director is already on a different chassis, then no additional directors are required.

New Connection Ownership

When a new connection is directed to a member of the cluster via load balancing, that unit owns both directions of the connection. If any connection packets arrive at a different unit, they are forwarded to the owner unit over the cluster control link. If a reverse flow arrives at a different unit, it is redirected back to the original unit.

Sample Data Flow

The following example shows the establishment of a new connection.

1. The SYN packet originates from the client and is delivered to one Firepower Threat Defense device (based on the load balancing method), which becomes the owner. The owner creates a flow, encodes owner information into a SYN cookie, and forwards the packet to the server.

2. The SYN-ACK packet originates from the server and is delivered to a different Firepower Threat Defense device (based on the load balancing method). This Firepower Threat Defense device is the forwarder.

3. Because the forwarder does not own the connection, it decodes owner information from the SYN cookie, creates a forwarding flow to the owner, and forwards the SYN-ACK to the owner.

4. The owner sends a state update to the director, and forwards the SYN-ACK to the client.

5. The director receives the state update from the owner, creates a flow to the owner, and records the TCP state information as well as the owner. The director acts as the backup owner for the connection.

6. Any subsequent packets delivered to the forwarder will be forwarded to the owner.

7. If packets are delivered to any additional units, it will query the director for the owner and establish a flow.

8. Any state change for the flow results in a state update from the owner to the director.

Firepower Threat Defense Features and Clustering

Some Firepower Threat Defense features are not supported with clustering, and some are only supported on the primary unit. Other features might have caveats for proper usage.

Unsupported Features with Clustering

These features cannot be configured with clustering enabled, and the commands will be rejected.

- Site-to-site VPN

- Remote access VPN (SSL VPN and IPsec VPN)

- DHCP client, server, and proxy. DHCP relay is supported.

- High Availability

- Integrated Routing and Bridging

Centralized Features for Clustering

The following features are only supported on the primary unit, and are not scaled for the cluster.

Note

Traffic for centralized features is forwarded from member units to the primary unit over the cluster control link.

If you use the rebalancing feature, traffic for centralized features may be rebalanced to non-master units before the traffic is classified as a centralized feature; if this occurs, the traffic is then sent back to the primary unit.

For centralized features, if the primary unit fails, all connections are dropped, and you have to re-establish the connections on the new primary unit.

- The following application inspections:

- DCERPC

- NetBIOS

- RSH

- SUNRPC

- TFTP

- XDMCP

- Dynamic routing

- Static route monitoring

Dynamic Routing and Clustering

The routing process only runs on the primary unit, and routes are learned through the primary unit and replicated to secondaries. If a routing packet arrives at a secondary, it is redirected to the primary unit.

Dynamic Routing

After the secondary members learn the routes from the primary unit, each unit makes forwarding decisions independently.

The OSPF LSA database is not synchronized from the primary unit to secondary units. If there is a primary unit switchover, the neighboring router will detect a restart; the switchover is not transparent. The OSPF process picks an IP address as its router ID. Although not required, you can assign a static router ID to ensure a consistent router ID is used across the cluster. See the OSPF Non-Stop Forwarding feature to address the interruption.

NAT and Clustering

NAT can affect the overall throughput of the cluster. Inbound and outbound NAT packets can be sent to different Firepower Threat Defense devices in the cluster because the load balancing algorithm relies on IP addresses and ports, and NAT causes inbound and outbound packets to have different IP addresses and/or ports. When a packet arrives at the Firepower Threat Defense device that is not the connection owner, it is forwarded over the cluster control link to the owner, causing large amounts of traffic on the cluster control link.

If you still want to use NAT in clustering, then consider the following guidelines:

- NAT pool address distribution for dynamic PAT—The primary unit evenly pre-distributes addresses across the cluster. If a member receives a connection and they have no addresses left, then the connection is dropped even if other members still have addresses available. Make sure to include at least as many NAT addresses as there are units in the cluster to ensure that each unit receives an address.

- No round-robin—Round-robin for a PAT pool is not supported with clustering.

- Dynamic NAT xlates managed by the primary unit—The primary unit maintains and replicates the xlate table to secondary units. When a secondary unit receives a connection that requires dynamic NAT, and the xlate is not in the table, it requests the xlate from the primary unit. The secondary unit owns the connection.

- No static PAT for the following inspections—

- FTP

- RSH

- SQLNET

- TFTP

- XDMCP

- SIP

SIP Inspection and Clustering

A control flow can be created on any unit (due to load balancing); its child data flows must reside on the same unit.

Syslog and Clustering

- Each unit in the cluster generates its own syslog messages. You can configure logging so that each unit uses either the same or a different device ID in the syslog message header field. For example, the hostname configuration is replicated and shared by all units in the cluster. If you configure logging to use the hostname as the device ID, syslog messages generated by all units look as if they come from a single unit. If you configure logging to use the local-unit name that is assigned in the cluster bootstrap configuration as the device ID, syslog messages look as if they come from different units.

SNMP and Clustering

An SNMP agent polls each individual Firepower Threat Defense device by its Diagnostic interface Local IP address. You cannot poll consolidated data for the cluster.

You should always use the Local address, and not the Main cluster IP address for SNMP polling. If the SNMP agent polls the Main cluster IP address, if a new primary is elected, the poll to the new primary unit will fail.

FTP and Clustering

- If FTP data channel and control channel flows are owned by different cluster members, then the data channel owner will periodically send idle timeout updates to the control channel owner and update the idle timeout value. However, if the control flow owner is reloaded, and the control flow is re-hosted, the parent/child flow relationship will not longer be maintained; the control flow idle timeout will not be updated.

Cisco TrustSec and Clustering

Only the primary unit learns security group tag (SGT) information. The primary unit then populates the SGT to secondaries, and secondaries can make a match decision for SGT based on the security policy.

Prerequisites for Clustering

Inter-Chassis Hardware and Software Requirements

All chassis in a cluster:

- For the Firepower 4100 series: All chassis must be the same model. For the Firepower 9300: All security modules must be the same type. You can have different quantities of installed security modules in each chassis, although all modules present in the chassis must belong to the cluster including any empty slots.

- Must run the identical FXOS software except at the time of an image upgrade.

- Must include the same interface configuration for interfaces you assign to the cluster, such as the same Management interface, EtherChannels, active interfaces, speed and duplex, and so on. You can use different network module types on the chassis as long as the capacity matches for the same interface IDs and interfaces can successfully bundle in the same spanned EtherChannel. Note that all data interfaces must be EtherChannels in inter-chassis clustering.

- Must use the same NTP server. For Firepower Threat Defense, the Firepower Management Center must also use the same NTP server. Do not set the time manually.

Switch Prerequisites for Inter-Chassis Clustering

- Be sure to complete the switch configuration and successfully connect all the EtherChannels from the chassis to the switch(es) before you configure clustering on the Firepower 4100/9300 chassis.

- For a list of supported switches, see Cisco FXOS Compatibility.

Guidelines for Clustering

Models

- Firepower Threat Defense on the Firepower 9300—Supported for intra-chassis and inter-chassis clustering.

- Firepower Threat Defense on the Firepower 4100 series—Supported for inter-chassis clustering.

- Radware DefensePro—Supported for intra-chassis clustering with the Firepower Threat Defense.

Switches for Inter-Chassis Clustering

- For the ASR 9006, if you want to set a non-default MTU, set the ASR interface MTU to be 14 bytes higher than the cluster device MTU. Otherwise, OSPF adjacency peering attempts may fail unless the mtu-ignore option is used. Note that the cluster device MTU should match the ASR IPv4 MTU.

- On the switch(es) for the cluster control link interfaces, you can optionally enable Spanning Tree PortFast on the switch ports connected to the cluster unit to speed up the join process for new units.

- When you see slow bundling of a Spanned EtherChannel on the switch, you can enable LACP rate fast for an individual interface on the switch. Note that some switches, such as the Nexus series, do not support LACP rate fast when performing in-service software upgrades (ISSUs), so we do not recommend using ISSUs with clustering.

- On the switch, we recommend that you use one of the following EtherChannel load-balancing algorithms: source-dest-ip or source-dest-ip-port (see the Cisco Nexus OS and Cisco IOS port-channel load-balance command). Do not use a vlan keyword in the load-balance algorithm because it can cause unevenly distributed traffic to the devices in a cluster.

- If you change the load-balancing algorithm of the EtherChannel on the switch, the EtherChannel interface on the switch temporarily stops forwarding traffic, and the Spanning Tree Protocol restarts. There will be a delay before traffic starts flowing again.

- Switches on the cluster control link path should not verify the L4 checksum. Redirected traffic over the cluster control link does not have a correct L4 checksum. Switches that verify the L4 checksum could cause traffic to be dropped.

- Port-channel bundling downtime should not exceed the configured keepalive interval.

- On Supervisor 2T EtherChannels, the default hash distribution algorithm is adaptive. To avoid asymmetric traffic in a VSS design, change the hash algorithm on the port-channel connected to the cluster device to fixed:

router(config)# port-channel id hash-distribution fixed

Do not change the algorithm globally; you may want to take advantage of the adaptive algorithm for the VSS peer link.

EtherChannels for Inter-Chassis Clustering

- For connecting switches, set the EtherChannel mode to Active; On mode is not supported on the Firepower 4100/9300 chassis, even for the cluster control link.

- FXOS EtherChannels have the LACP rate set to normal by default. This setting can make port-channel members take more than 30 seconds to bundle, which can cause the cluster interface health check to fail causing the unit to be removed from the cluster. We recommend that you change the LACP rate to fast in the FXOS CLI. The following example modifies the "default" LACP policy:

firepower# scope org
firepower /org # scope lacppolicy default
firepower /org/lacppolicy# set lacp-rate fast
firepower /org* # commit-buffer

- In Catalyst 3750-X Cisco IOS software versions earlier than 15.1(1)S2, the cluster unit did not support connecting an EtherChannel to a switch stack. With default switch settings, if the cluster unit EtherChannel is connected cross stack, and if the master switch is powered down, then the EtherChannel connected to the remaining switch will not come up. To improve compatibility, set the stack-mac persistent timer command to a large enough value to account for reload time; for example, 8 minutes or 0 for indefinite. Or, you can upgrade to more a more stable switch software version, such as 15.1(1)S2.

- Spanned vs. Device-Local EtherChannel Configuration—Be sure to configure the switch appropriately for Spanned EtherChannels vs. Device-local EtherChannels.

- Spanned EtherChannels—For cluster unit Spanned EtherChannels, which span across all members of the cluster, the interfaces are combined into a single EtherChannel on the switch. Make sure each interface is in the same channel group on the switch.

- Device-local EtherChannels—For cluster unit Device-local EtherChannels including any EtherChannels configured for the cluster control link, be sure to configure discrete EtherChannels on the switch; do not combine multiple cluster unit EtherChannels into one EtherChannel on the switch.

Additional Guidelines

- You can include up to 6 modules in the cluster in up to 6 chassis.

- When adding a unit to an existing cluster, or when reloading a unit, there will be a temporary, limited packet/connection drop; this is expected behavior. In some cases, the dropped packets can hang connections; for example, dropping a FIN/ACK packet for an FTP connection will make the FTP client hang. In this case, you need to reestablish the FTP connection.

- If you use a Windows 2003 server connected to a Spanned interface, when the syslog server port is down, and the server does not throttle ICMP error messages, then large numbers of ICMP messages are sent back to the cluster. These messages can result in some units of the cluster experiencing high CPU, which can affect performance. We recommend that you throttle ICMP error messages.

- We recommend connecting EtherChannels to a VSS or vPC for redundancy.

- Within a chassis, you cannot cluster some security modules and run other security modules in standalone mode; you must include all security modules in the cluster, including empty slots.

Defaults for Clustering on the Firepower 4100/9300 Chassis

- The cluster health check feature is enabled by default with the holdtime of 3 seconds. Interface health monitoring is enabled on all interfaces by default.

- The cluster auto-rejoin feature for a failed cluster control link is set to unlimited attempts every 5 minutes.

- The cluster auto-rejoin feature for a failed data interface is set to 3 attempts every 5 minutes, with the increasing interval set to 2.

- Connection replication delay of 5 seconds is enabled by default for HTTP traffic.

Configure Clustering on the Firepower 4100/9300 Chassis

You can easily deploy the cluster from the Firepower 4100/9300 chassis supervisor. All initial configuration is automatically generated for each unit. You can then add the units to the Management Center and group them into a cluster.

Deploy the Cluster from the FXOS Chassis Supervisor

You can easily deploy the cluster from the Firepower 4100/9300 chassis supervisor. All initial configuration is automatically generated for each unit. For inter-chassis clustering, you must configure each chassis separately. Deploy the cluster on one chassis; you can then copy the bootstrap configuration from the first chassis to the next chassis for ease of deployment.

Before You Begin

- You must enable clustering for all 3 module slots in a Firepower 9300 chassis, even if you do not have a module installed. If you do not configure all 3 modules, the cluster will not come up.

- On the Interfaces tab, the port-channel 48 cluster type interface shows the Operation State as failed if it does not include any member interfaces. For intra-chassis clustering, this EtherChannel does not require any member interfaces, and you can ignore this Operational State.

Procedure

Step 1

Add at least one Data type interface or EtherChannel (also known as a port-channel) before you deploy the cluster.
You can also add data interfaces to the cluster after you deploy it.

For inter-chassis clustering, all data interfaces must be EtherChannels with at least one member interface. Add the same EtherChannels on each chassis.

Step 2

Add a Management type interface or EtherChannel.
For inter-chassis clustering, add the same Management interface on each chassis. The management interface is required. Note that this management interface is not the same as the chassis management interface that is used only for chassis management (and that appears at the top of the Interfaces tab as MGMT).

Step 3

For inter-chassis clustering, add a member interface to port-channel 48, which is used as the cluster control link.
If you do not include a member interface, then when you deploy the logical device, the Firepower Chassis Manager assumes that this cluster is an intra-chassis cluster and does not show the Chassis ID field. Add the same member interfaces on each chassis.

Step 4

(Optional)Add a Firepower-eventing interface.
This interface is a secondary management interface for Firepower Threat Defense devices. To use this interface, you must configure its IP address and other parameters at the Firepower Threat Defense CLI. For example, you can separate management traffic from events (such as web events). See the configure network commands in the Firepower Threat Defense command reference.

For inter-chassis clustering, add the same eventing interface on each chassis.

Step 5

Choose Logical Devices to open the Logical Devices page.
The Logical Devices page shows a list of configured logical devices on the chassis. If no logical devices have been configured, a message stating so is shown instead.

Step 6

Click Add Device to open the Add Device dialog box.
If you have an existing logical device, you are prompted to remove the device and add a new one. All configuration on the device(s) will be replaced by the new information.

Step 7

For the Device Name, provide a name for the logical device. This name is used by the Firepower 4100/9300 chassis supervisor to configure clustering/management settings and to assign interfaces; it is not the cluster name used in the logical device configuration.

Step 8

For the Template, choose Cisco Firepower Threat Defense.

Step 9

For the Image Version, choose the Firepower Threat Defense software version. Make sure this version is compatible with your FXOS version and with the Firepower Management Center version.

Step 10

For the Device Mode, click the Cluster radio button.

Step 11

Click the Create New Cluster radio button.

Step 12

Click OK.
If you have any standalone devices configured, you are prompted to replace them with a new cluster. You see the Provisioning - device name window.

All interfaces are assigned to the cluster by default. Hardware Bypass-capable ports are shown with the following icon: . If you do not assign both interfaces in a Hardware Bypass pair, you see a warning message to make sure your assignment is intentional. You do not need to use the Hardware Bypass feature, so you can assign single interfaces if you prefer. Hardware Bypass ports are not supported in inter-chassis clustering because they are not supported as EtherChannel members.

Step 13

Click the device icon in the center of the screen.
The Cisco Firepower Threat Defense Configuration dialog box appears.

Step 14

On the Cluster Information tab, complete the following:

1. In the Chassis ID field, enter a chassis ID. Each chassis in the cluster must use a unique ID.

2. In the Cluster Key field, configure an authentication key for control traffic on the cluster control link.
The shared secret is an ASCII string from 1 to 63 characters. The shared secret is used to generate the key. This option does not affect datapath traffic, including connection state update and forwarded packets, which are always sent in the clear.

3. Set the Cluster Group Name, which is the cluster group name in the logical device configuration.
The name must be an ASCII string from 1 to 38 characters.

4. Select the management interface to use with the logical device from the Management Interface drop-down list.
If you assign a Hardware Bypass-capable interface as the Management interface, you see a warning message to make sure your assignment is intentional.

Step 15

On the Settings tab, complete the following:

1. In the Registration Key field, enter the key to be shared between the Firepower Management Center and the cluster members during registration.

2. In the Password field, enter a password for the admin user on the cluster.

3. In the Firepower Management Center IP field, enter the IP address of the managing Firepower Management Center.

4. In the Search Domains field, enter a comma-separated list of search domains for the management network.

5. From the Firewall Mode drop-down list, choose Transparent or Routed.

6. In the DNS Servers field, enter a comma-separated list of DNS servers that the Firepower Threat Defense device should use on the management network.

7. In the Fully Qualified Hostname field, enter a fully qualified name for the Firepower Threat Defense device.

8. From the Eventing Interface drop-down list, choose the interface on which Firepower events should be sent. If not specified, the management interface will be used.
To specify a separate interface to use for Firepower events, you must configure an interface as a firepower-eventing interface. If you assign a Hardware Bypass-capable interface as the Eventing interface, you see a warning message to make sure your assignment is intentional.

Step 16

On the Interface Information tab, configure a management IP address for each security module in the cluster. Select the type of address from the Address Type drop-down list and then complete the following for each security module.
Note:
You must set the IP address for all 3 module slots in a chassis, even if you do not have a module installed. If you do not configure all 3 modules, the cluster will not come up.

1. In the Management IP field, configure an IP address.
Specify an IP address on the same network for each module.

2. Enter a Network Mask or Prefix Length.

3. Enter a Network Gateway address.

Step 17

On the Agreement tab, read and accept the end user license agreement (EULA).

Step 18

Click OK to close the Cisco Firepower Threat Defense Configuration dialog box.

Step 19

Click Save.
The Firepower 4100/9300 chassis supervisor deploys the cluster by downloading the specified software version and pushing the cluster bootstrap configuration and management interface settings to each security module.

Step 20

For inter-chassis clustering, add the next chassis to the cluster:

1. On the first chassis Firepower Chassis Manager, click the Show Cluster Details icon at the top right; copy the displayed cluster configuration.

2. Connect to the Firepower Chassis Manager on the next chassis, and add a logical device according to this procedure.

3. Choose Join an Existing Cluster.

4. Click the Copy config check box, and click OK. If you uncheck this check box, you must manually enter the settings to match the first chassis configuration.

5. In the Copy Cluster Details box, paste in the cluster configuration from the first chassis, and click OK.

6. Click the device icon in the center of the screen. The cluster information is mostly pre-filled, but you must change the following settings:

- Chassis ID—Enter a unique chassis ID.

- Cluster Key—(Not prefilled) Enter the same cluster key.

- Management IP—Change the management address for each module to be a unique IP address on the same network as the other cluster members.

Click OK.

7. Click Save.

Step 21

Add each unit separately to the Firepower Management Center using the management IP addresses, and then group them into a cluster at the web interface.
All cluster units must be in a successfully-formed cluster on FXOS prior to adding them to Firepower Management Center.

Add a Cluster to the Management Center

Smart License

Classic License

Supported Devices

Supported Domains

Access

Any

N/A

Firepower Threat Defense on the Firepower 4100 and 9300

Any

Access Admin
Administrator
Network Admin

Add the logical devices to the Management Center, and then group them into a cluster.

Before You Begin

- Refer to the Firepower Chassis Manager Logical Devices screen to see which unit is the primary unit.

- All cluster units must be in a successfully formed cluster on FXOS prior to adding them to the Management Center.

Procedure

Step 1

In the Management Center, choose Devices > Device Management, and choose Add > Add Device to add each unit as a separate managed device using the management IP addresses you assigned when you deployed the cluster.
Note:
If you use Management Center High Availability, make sure the standby Management Center also successfully registers each unit before you continue and form the cluster on the active Management Center: Log into the standby Management Center to check the registration status of each unit.

Step 2

Choose Add > Add Cluster to group the units into a cluster.

1. Choose the Primary device from the drop-down list.
All other eligible members are added to the Secondary Devices box.

2. Specify a Name for the cluster.

3. Click OK.
The cluster object is added to the Devices screen, with the member units underneath. The current primary unit is indicated by "(primary)" after the unit name.

Note:
If you add more units to the cluster later on the FXOS chassis, then you must add each unit to the Management Center, and then add them as secondary nodes of the cluster as soon as possible.

Step 3

To configure device-specific settings, click the edit icon () for the cluster; you can only configure the cluster as a whole, and not member units in the cluster.

Step 4

On the Devices > Device Management > Cluster tab, you can see General, License, System, and Health settings. This tab is most useful for setting license entitlements. On the Devices tab, you can change the management IP address for the primary unit only.

Step 5

(Optional)If you want to configure the Diagnostic interface, perform the following steps:
The Diagnostic interface is the only interface that can run in Individual interface mode. You can use this interface for syslog messages or SNMP, for example.

1. Add an IPv4 and/or IPv6 address pool.

2. Click the Interfaces tab to edit the Diagnostic interface.

3. On the IPv4 tab, enter the Virtual IP Address and mask. This IP address is a fixed address for the cluster, and always belongs to the current primary unit.

4. From the IPv4 Address Pool drop-down list, choose the address pool you created.

Include at least as many addresses as there are units in the cluster. The Virtual IP address is not a part of this pool, but needs to be on the same network. You cannot determine the exact Local address assigned to each unit in advance.

5. For the Mask, enter the subnet mask for the cluster IP pool.

6. On the IPv6 > Basic tab, from the IPv6 Address Pool drop-down list, choose the address pool you created.

7. Configure other interface settings as normal.

Step 6

Configure other device-level settings as desired.

Step 7

Click Save, and then Deploy.

Add a Cluster Member

Smart License

Classic License

Supported Devices

Supported Domains

Access

Any

N/A

Firepower Threat Defense on the Firepower 4100 and 9300

Any

Access Admin
Administrator
Network Admin

You can add a new cluster member to an existing cluster, for example, when you add an additional module to the Firepower 9300 device, or an additional chassis.

Before You Begin

When you add more units to the cluster on the FXOS chassis, then you must add each unit to the Management Center, and then add them as secondary nodes of the cluster as soon as possible.

Procedure

Step 1

In the Management Center, choose Devices > Device Management, and choose Add > Add Device to add the new logical device.

Step 2

Choose Add > Add Cluster.

Step 3

Choose the current Primary device from the drop-down list.
When you choose a primary device that is already in a cluster, then the existing cluster name is auto-filled, and all eligible secondary devices are added to the Secondary Devices box, including the new unit you just added to the Management Center.

Step 4

Click Add, and then Deploy.
The cluster is updated to include the new member(s).

Delete a Secondary Member

Smart License

Classic License

Supported Devices

Supported Domains

Access

Any

N/A

Firepower Threat Defense on the Firepower 4100 and 9300

Any

Access Admin
Administrator
Network Admin

If you need to remove a cluster member (for example, if you remove a module on the Firepower 9300, or remove a chassis), then you should delete it from the Management Center. Do not delete the member if it is still a healthy part of the cluster according to the Firepower Chassis Manager; even though you removed it from the Management Center, it will still be an operational part of the cluster, which can cause problems if it became the primary unit and the Management Center can no longer manage it.

Procedure

Step 1

In the Management Center, choose Devices > Device Management, and click the trash can next to the secondary unit.

Step 2

Confirm that you want to delete the unit.
The unit is removed from the cluster and from the Management Center devices list.

Rejoin the Cluster

Smart License

Classic License

Supported Devices

Supported Domains

Access

Any

N/A

Firepower Threat Defense on the Firepower 4100 and 9300

Any

Access Admin
Administrator
Network Admin

If a unit was removed from the cluster, for example for a failed interface, you must manually rejoin the cluster by accessing the unit CLI. Make sure the failure is resolved before you try to rejoin the cluster. See Rejoining the Cluster for more information about why a unit can be removed from a cluster.

Procedure

Step 1

Access the CLI of the unit that needs to rejoin the cluster, either from the console port or using SSH to the Management interface. Log in with the username admin and the password you set during initial setup.

Step 2

Enable clustering:
cluster enable

History for Clustering

Feature Name

Platform Releases

Feature Information

Intra-chassis Clustering for the Cisco ASA

1.1.1

You can cluster all ASA security modules within the Firepower 9300 chassis.

We introduced the following screen: Logical Devices > Configuration

Inter-chassis clustering for 6 ASA modules

1.1.3

You can now enable inter-chassis clustering for the ASA. You can include up to 6 modules in up to 6 chassis.

We modified the following screen: Logical Devices > Configuration

Support for intra-chassis clustering on the Firepower Threat Defense on the Firepower 9300

1.1.4

The Firepower 9300 supports intra-chassis clustering with the Firepower Threat Defense application.

We modified the following screen: Logical Devices > Configuration

Inter-site clustering improvement for the ASA on the Firepower 4100/9300 chassis

2.1.1

You can now configure the site ID for each Firepower 4100/9300 chassis when you deploy the ASA cluster. Previously, you had to configure the site ID within the ASA application; this new feature eases initial deployment. Note that you can no longer set the site ID within the ASA configuration. Also, for best compatibility with inter-site clustering, we recommend that you upgrade to ASA 9.7(1) and FXOS 2.1.1, which includes several improvements to stability and performance.

We modified the following screen: Logical Devices > Configuration

Inter-chassis clustering for 6 Firepower Threat Defense modules

2.1.1

You can now enable inter-chassis clustering for the Firepower Threat Defense. You can include up to 6 modules in up to 6 chassis.

We modified the following screen: Logical Devices > Configuration

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