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Updated:March 5, 2025
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First Published: March 5, 2025
Deploy a Cluster for the ASA
Virtual for the Private Cloud
Clustering lets you group multiple ASA
virtual's together as a single logical device. 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. You can deploy the ASA
virtual clusters using:
This section describes the clustering architecture and how it works.
How the Cluster Fits into Your Network
The cluster consists of multiple firewalls acting as a single
device. To act as a cluster, the firewalls need the following infrastructure:
Isolated network for intra-cluster communication, known as
the cluster control link, using VXLAN interfaces.
VXLANs, which act as Layer 2 virtual networks over Layer 3 physical networks,
let the ASA virtual send broadcast/multicast messages over the cluster control link.
Management access to each firewall for configuration and
monitoring. The ASA virtual deployment includes a Management 0/0 interface that you will use to manage
the cluster nodes.
When you place the cluster in your network, the upstream and
downstream routers need to be able to load-balance the data coming to and from the
cluster using Layer 3 Individual interfaces and one of the following methods:
Policy-Based Routing—The upstream and downstream routers
perform load balancing between nodes using route maps and ACLs.
Equal-Cost Multi-Path Routing—The upstream and downstream
routers perform load balancing between nodes using equal cost static or dynamic
routes.
Note
Layer 2 Spanned EtherChannels are not supported.
Cluster Nodes
Cluster nodes work together to accomplish the sharing of the security
policy and traffic flows. This section describes the nature of each node role.
Bootstrap
Configuration
On each device, you configure a minimal bootstrap configuration
including the cluster name, cluster control link interface, and other cluster settings.
The first node on which you enable clustering typically becomes the control node. When you enable clustering on subsequent
nodes, they join the cluster as data nodes.
Control and Data Node Roles
One member of the cluster
is the control node. If multiple cluster nodes come online at the same time, the control node
is determined by the priority setting in the bootstrap
configuration; the priority is set between 1 and 100, where 1 is the highest priority.
All other members are data nodes. Typically, when you first create a
cluster, the first node you add becomes the control node simply because it is the only node
in the cluster so far.
You
must perform all configuration (aside from the bootstrap configuration) on the control node
only; the configuration is then replicated to the data nodes. In the case of physical assets,
such as interfaces, the configuration of the control node is mirrored on all data nodes. For
example, if you configure Ethernet 1/2 as the inside interface and Ethernet 1/1 as the outside
interface, then these interfaces are also used on the data nodes as inside and outside
interfaces.
Some features do not scale
in a cluster, and the control node handles all traffic for those features.
Individual Interfaces
You can configure cluster interfaces as Individual
interfaces.
Individual interfaces are normal routed interfaces, each with their own
Local IP address used for routing. The Main cluster IP address for each interface is a
fixed address that always belongs to the control node. When the control node
changes, the Main cluster IP address moves to the new control node, so
management of the cluster continues seamlessly.
Because interface configuration must be configured only on the control node, you
configure a pool of IP addresses to be used for a given interface on the cluster
nodes, including one for the control node.
Load balancing must be configured separately on the
upstream switch.
Note
Layer 2 Spanned EtherChannels are not supported.
Policy-Based Routing
When using Individual interfaces, each ASA interface maintains its own IP address and MAC address. One method of load balancing
is Policy-Based Routing (PBR).
We recommend this method if you are already using PBR, and want to
take advantage of your existing infrastructure.
PBR makes routing decisions based on a route map and ACL. You must
manually divide traffic between all ASAs in a cluster. Because PBR is static, it may not achieve the optimum load balancing
result at all times. To achieve the best performance, we recommend that you configure
the PBR policy so that forward and return packets of a connection are directed to the
same ASA. For example, if you have a Cisco router, redundancy can be achieved by using Cisco
IOS PBR with Object Tracking. Cisco IOS Object Tracking monitors each ASA using ICMP ping. PBR can then enable or disable route maps based on reachability of a
particular ASA. See the following URLs for more details:
When using Individual interfaces, each ASA interface maintains its own IP address and MAC address. One method of load balancing
is Equal-Cost Multi-Path (ECMP) routing.
We recommend this method if you are already using ECMP, and want to
take advantage of your existing infrastructure.
ECMP routing can forward packets over multiple “best paths” that
tie for top place in the routing metric. Like EtherChannel, a hash of source and
destination IP addresses and/or source and destination ports can be used to send a
packet to one of the next hops. If you use static routes for ECMP routing, then the ASA failure can cause problems; the route continues to be used, and traffic to the failed
ASA will be lost. If you use static routes, be sure to use a static route monitoring
feature such as Object Tracking. We recommend using dynamic routing protocols to add and
remove routes, in which case, you must configure each ASA to participate in dynamic routing.
Cluster Control Link
Each node must dedicate one interface as a VXLAN (VTEP)
interface for the cluster control link.
VXLAN Tunnel Endpoint
VXLAN tunnel endpoint (VTEP) devices perform
VXLAN encapsulation and decapsulation. Each VTEP has two interface types: one or
more virtual interfaces called VXLAN Network Identifier (VNI) interfaces, and a
regular interface called the VTEP source interface that tunnels the VNI interfaces
between VTEPs. The VTEP source interface is attached to the transport IP network for
VTEP-to-VTEP communication.
VTEP Source Interface
The VTEP source interface is a regular ASA virtual interface with which you plan to associate the VNI interface. You can configure
one VTEP source interface to act as the cluster control link. The source interface
is reserved for cluster control link use only. Each VTEP source interface has an IP
address on the same subnet. This subnet should be isolated from all other traffic,
and should include only the cluster control link interfaces.
VNI Interface
A VNI interface is similar to a VLAN
interface: it is a virtual interface that keeps network traffic separated on a given
physical interface by using tagging. You can only configure one VNI interface. Each
VNI interface has an IP address on the same subnet.
Peer VTEPs
Unlike regular VXLAN for data interfaces, which allows a single VTEP peer, The ASA virtual clustering allows you to configure multiple peers.
Cluster Control Link Traffic Overview
Cluster control link traffic includes both control and data
traffic.
Control traffic includes:
Control node election.
Configuration replication.
Health monitoring.
Data traffic includes:
State replication.
Connection ownership queries and data packet forwarding.
Cluster Control Link Failure
If the cluster control link line protocol goes down for a unit,
then clustering is disabled; data interfaces are shut down. After you fix the cluster
control link, you must manually rejoin the cluster by re-enabling clustering.
Note
When the ASA
virtual becomes inactive, all data interfaces are shut down; only the management-only
interface can send and receive traffic. The management interface remains up using
the IP address the unit received from DHCP or the cluster IP pool. If you use a
cluster IP pool, if you reload and the unit is still inactive in the cluster, then
the management interface is not accessible (because it then uses the Main IP
address, which is the same as the control node). You must use the console port (if
available) for any further configuration.
Configuration Replication
All nodes in the cluster share a single configuration. You can only make
configuration changes on the control node (with the exception of the bootstrap
configuration), and changes are automatically synced to all other nodes in the
cluster.
ASA
Virtual Cluster Management
One of the benefits of using ASA
virtual clustering is the ease of management. This section describes how to manage the cluster.
Management Network
We recommend connecting all nodes to a single management network.
This network is separate from the cluster control link.
Management Interface
Use the Management 0/0 interface for management.
Note
You cannot enable dynamic routing for the management interface.
You must use a static route.
You can use either static addressing or DHCP for the management IP
address.
If you use static addressing, you can use a Main cluster IP address
that is a fixed address for the cluster that always belongs to the current control node.
For each interface, you also configure a range of addresses so that each node, including
the current control node, can use a Local address from the range. The Main cluster IP
address provides consistent management access to an address; when a control node
changes, the Main cluster IP address moves to the new control node, so management of the
cluster continues seamlessly. The Local IP address is used for routing, and is also
useful for troubleshooting. For example, you can manage the cluster by connecting to the
Main cluster IP address, which is always attached to the current control node. To manage
an individual member, you can connect to the Local IP address. For outbound management
traffic such as TFTP or syslog, each node, including the control node, uses the Local IP
address to connect to the server.
If you use DHCP, you do not use a pool of Local addresses or have a Main cluster IP
address.
Note
To-the-box traffic needs to be directed to the node's management IP address;
to-the-box traffic is not forwarded over the cluster control link to any other
node.
Control Node Management Vs. Data Node Management
All management and monitoring can take place on the control node. From
the control node, you can check runtime statistics, resource usage, or other
monitoring information of all nodes. You can also issue a command to all nodes
in the cluster, and replicate the console messages from data nodes to the
control node.
You can monitor data nodes directly if desired. Although also available
from the control node, you can perform file management on data nodes (including
backing up the configuration and updating images). The following functions are
not available from the control node:
Monitoring per-node cluster-specific statistics.
Syslog monitoring per node (except for syslogs sent to the console when
console replication is enabled).
SNMP
NetFlow
Crypto Key Replication
When you create a crypto key on the control node, the key is replicated
to all data nodes. If you have an SSH session to the Main cluster IP address,
you will be disconnected if the control node fails. The new control node uses
the same key for SSH connections, so that you do not need to update the cached
SSH host key when you reconnect to the new control node.
ASDM Connection Certificate IP Address Mismatch
By default, a self-signed certificate is used for the ASDM connection
based on the Local IP address. If you connect to the Main cluster IP address
using ASDM, then a warning message about a mismatched IP address might appear
because the certificate uses the Local IP address, and not the Main cluster IP
address. You can ignore the message and establish the ASDM connection. However,
to avoid this type of warning, you can enroll a certificate that contains the
Main cluster IP address and all the Local IP addresses from the IP address pool.
You can then use this certificate for each cluster member. See https://www.cisco.com/c/en/us/td/docs/security/asdm/identity-cert/cert-install.html for more information.
Inter-Site Clustering
For inter-site installations, you can take advantage of ASA
virtual clustering as long as you follow the recommended guidelines.
You can configure each cluster chassis to belong to a separate site ID. Site IDs
are used to enable flow mobility using LISP inspection, director localization to
improve performance and reduce round-trip time latency for inter-site clustering
for data centers, and site redundancy for connections where a backup owner of a
traffic flow is always at a different site from the owner.
See the following sections for more information about inter-site clustering:
Each cluster node requires the same model license. We recommend using the same number
of CPUs and memory for all nodes, or else peformance will be limited on all nodes to
match the least capable member. The throughput level will be replicated from the
control node to each data node so they match.
Note
If you deregister the ASA
virtual so that it is unlicensed, then it will revert to a severely rate-limited
state if you reload the ASA
virtual. An unlicensed, low performing cluster node will impact the performance of
the entire cluster negatively. Be sure to keep all cluster nodes licensed, or
remove any unlicensed nodes.
Requirements and Prerequisites for ASA
Virtual Clustering
Model Requirements
ASAv30, ASAv50, ASAv100
The following private cloud services:
KVM with ASA 9.17+
VMware with ASA 9.17+
A maximum of 16 nodes in a cluster on two hosts in a 2x8 deployment
configuration. We recommend you to deploy a maximum of eight ASAvs on
each of the two hosts (2x8), which results in a cluster of 16
nodes.
ASA
Virtual Platform and Software Requirements
All nodes in a cluster:
Must be the same model. We recommend
using the same number of CPUs and memory for all nodes, or else peformance
will be limited on all nodes to match the least capable node.
Must run the identical software
except at the time of an image upgrade. Hitless upgrade is supported.
Mismatched software versions can lead to poor performance, so be sure to
upgrade all nodes in the same maintenance window.
New cluster members must use the same SSL encryption
setting (the ssl encryption command) as the
control node for initial cluster control link communication before
configuration replication.
Guidelines for ASA
Virtual Clustering
Failover
Failover is not
supported with clustering.
IPv6
The cluster control link
is only supported using IPv4.
Additional Guidelines
When significant topology changes occur (such as
enabling or disabling an interface on the ASA or the switch, adding an
additional switch to form a VSS or vPC) you should disable the health check
feature and also disable interface monitoring for the disabled interfaces.
When the topology change is complete, and the configuration change is synced
to all nodes, you can re-enable the interface health check feature.
When adding a node to an existing cluster, or when
reloading a node, there will be a temporary, limited packet/connection drop;
this is expected behavior. In some cases, the dropped packets can hang your
connection; 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.
We do not support VXLANs for data interfaces; only the
cluster control link supports VXLAN.
It takes time to replicate changes to all the nodes in a cluster. If you make
a large change, for example, adding an access control rule that uses object
groups (which, when deployed, are broken out into multiple rules), the time
needed to complete the change can exceed the timeout for the cluster nodes
to respond with a success message. If this happens, you might see a "failed
to replicate command" message. You can ignore the message.
Defaults for ASA
Virtual Clustering
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
unlimited attempts every 5 minutes.
The cluster auto-rejoin feature for a failed data interface is 3 attempts
every 5 minutes, with the increasing interval set to 2.
Connection rebalancing is disabled by default. If you
enable connection rebalancing, the default time between load information
exchanges is 5 seconds.
Connection replication delay of 5 seconds is enabled by default for HTTP
traffic.
Configure the ASA
Virtual Clustering Using a Day0 Configuration
Control Node Day0 Configuration
The following Day0 configuration for the control node includes the bootstrap
configuration followed by interface configuration that will be replicated to the
data nodes. Bold text shows the values you need to change for the data node Day0
configuration.
Note
This configuration only includes the cluster-centric configuration. Your Day0
configuration should also include other settings for licensing, SSH access, ASDM
access and more. See the getting started guide for more information about Day0
configurations.
!BOOTSTRAP
! Cluster interface mode
cluster interface mode individual
!
! VXLAN peer group
object-group network cluster-peers
network-object host 10.6.6.51
network-object host 10.6.6.52
network-object host 10.6.6.53
network-object host 10.6.6.54
!
! Alternate object group representation
! object-network xyz
! range 10.6.6.51 10.6.6.54
! object-group network cluster-peers
! network-object object xyz
!
! Cluster control link physical interface (VXLAN tunnel endpoint (VTEP) src interface)
interface gigabitethernet 0/7
description CCL VTEP src ifc
nve-only cluster
nameif ccl
security-level 0
ip address 10.6.6.51 255.255.255.0
no shutdown
!
! VXLAN Network Identifier (VNI) interface
interface vni1
segment-id 1
vtep-nve 1
!
! Set the CCL MTU
mtu ccl 1654
!
! Network Virtualization Endpoint (NVE) association with VTEP src interface
nve 1
encapsulation vxlan
source-interface ccl
peer-group cluster-peers
!
! Management Interface Using DHCP
interface management 0/0
nameif management
ip address dhcp setroute
no shutdown
!
! Alternate Management Using Static IP
! ip local pool mgmt_pool 10.1.1.1 10.10.10.4
! interface management 0/0
! nameif management
! ip address 10.1.1.25 255.255.255.0 cluster-pool mgmt_pool
! no shutdown
!
! Cluster Config
cluster group cluster1
local-unit A
cluster-interface vni1 ip 10.2.2.1 255.255.255.0
priority 1
enable noconfirm
!
! INTERFACES
!
ip local pool inside_pool 10.10.10.11 10.10.10.14
ip local pool outside_pool 10.11.11.11 10.11.11.14
!
interface GigabitEthernet0/1
nameif inside
security-level 100
ip address 10.10.10.10 255.255.255.0 cluster-pool inside_pool
!
interface GigabitEthernet0/0
nameif outside
security-level 0
ip address 10.11.11.10 255.255.255.0 cluster-pool outside_pool
!
!JUMBO FRAME RESERVATION for CCL MTU
jumbo-frame reservation
Data Node Day0 Configuration
The following Day0 configuration for the data node includes only the bootstrap
configuration. Bold text shows the values you need to change from the control node
Day0 configuration.
Note
This configuration only includes the cluster-centric configuration. Your Day0
configuration should also include other settings for licensing, SSH access, ASDM
access and more. See the getting started guide for more information about Day0
configurations.
!BOOTSTRAP
! Cluster interface mode
cluster interface mode individual
!
! VXLAN peer group
object-group network cluster-peers
network-object host 10.6.6.51
network-object host 10.6.6.52
network-object host 10.6.6.53
network-object host 10.6.6.54
!
! Alternate object group representation
! object-network xyz
! range 10.6.6.51 10.6.6.54
! object-group network cluster-peers
! network-object object xyz
!
! Cluster control link physical interface (VXLAN tunnel endpoint (VTEP) src interface)
interface gigabitethernet 0/7
description CCL VTEP src ifc
nve-only cluster
nameif ccl
security-level 0
ip address 10.6.6.52 255.255.255.0
no shutdown
!
! VXLAN Network Identifier (VNI) interface
interface vni1
segment-id 1
vtep-nve 1
!
! Set the CCL MTU
mtu ccl 1654
!
! Network Virtualization Endpoint (NVE) association with VTEP src interface
nve 1
encapsulation vxlan
source-interface ccl
peer-group cluster-peers
!
! Management Interface Using DHCP
interface management 0/0
nameif management
ip address dhcp setroute
no shutdown
!
! Alternate Management Using Static IP
! ip local pool mgmt_pool 10.1.1.1 10.10.10.4
! interface management 0/0
! nameif management
! ip address 10.1.1.25 255.255.255.0 cluster-pool mgmt_pool
! no shutdown
!
! Cluster Config
cluster group cluster1
local-unit B
cluster-interface vni1 ip 10.2.2.2 255.255.255.0
priority 2
enable noconfirm
!
! INTERFACES
!
ip local pool inside_pool 10.10.10.11 10.10.10.14
ip local pool outside_pool 10.11.11.11 10.11.11.14
!
interface GigabitEthernet0/1
nameif inside
security-level 100
ip address 10.10.10.10 255.255.255.0 cluster-pool inside_pool
!
interface GigabitEthernet0/0
nameif outside
security-level 0
ip address 10.11.11.10 255.255.255.0 cluster-pool outside_pool
!
!JUMBO FRAME RESERVATION for CCL MTU
jumbo-frame reservation
Configure ASA
Virtual Clustering after Deployment
To configure clustering after you deploy your ASA
virtuals, perform the following tasks.
Configure Interface Settings
Configure the cluster interface mode on each node as well as
interfaces on the control node. The interface configuration will be replicated to data
nodes when they join the cluster. Note that configuration of the cluster control link is
covered in the bootstrap configuration procedure.
Configure the Cluster Interface Mode on Each Node
Before you enable clustering, you need to convert the firewall to use Individual interfaces.
Because clustering limits the types of interfaces you can use, this process lets you
check your existing configuration for incompatible interfaces and then prevents you
from configuring any unsupported interfaces.
Before you begin
You must set the mode separately on each ASA
virtual that you want to add to the cluster.
Connect to the ASA
virtual CLI using either the console port (if available) or SSH (if configured). If neither of these options is available, you can
use ASDM to configure clustering.
Procedure
Step 1
Show any incompatible configuration so that you can
force the interface mode and fix your configuration later; the mode is not
changed with this command:
After you set the interface mode, you can continue
to connect to the interface using SSH; however,
if you reload the ASA before you configure your management interface to
comply with clustering requirements (for example, adding a cluster IP
pool or getting the IP address from DHCP), you will not be able to
reconnect because cluster-incompatible interface configuration is
removed. In that case, you will have to connect to the console port, if
available, to fix the interface configuration.
Step 2
Set the
interface mode for clustering:
cluster interface-mode individual force
Example:
ciscoasa(config)# cluster interface-mode individual force
There is no default setting; you must explicitly choose the
mode. If you have not set the mode, you cannot enable clustering.
The
force option changes the mode without checking your
configuration for incompatible settings. You need to manually fix any
configuration issues after you change the mode. Because any interface
configuration can only be fixed after you set the mode, we recommend using the
force option so that you can at least start from the
existing configuration. You can re-run the
check-details
option after you set the mode for more guidance.
Without the force option, if there is any
incompatible configuration, you are prompted to clear your configuration and
reload, thus requiring you to connect to the console port (if available) to
reconfigure your management access. If your configuration is compatible
(rare), the mode is changed and the configuration is preserved. If you do
not want to clear your configuration, you can exit the command by typing n.
To remove the interface mode, enter the
no cluster interface-mode command.
Configure Individual Interfaces
You must modify any interface that is currently configured with an IP address to be
cluster-ready before you enable clustering. At a minimum, you may need to modify the
management interface to which SSH
is currently connected when you use a static IP address for management. For other
interfaces, you can configure them before or after you enable clustering; we
recommend pre-configuring all of your interfaces so that the complete configuration
is synced to new cluster nodes.
This section describes how to configure interfaces to be
Individual interfaces compatible with clustering. Individual interfaces are normal
routed interfaces, each with their own IP address taken from a pool of IP addresses.
The Main cluster IP address is a fixed address for the cluster that always belongs
to the current control node. All data interfaces must be Individual interfaces.
For the Management interface, you can configure an IP address
pool or you can use DHCP; only the Management interface supports getting an address
from DHCP. To use DHCP, do not use this procedure; instead configure it as usual.
Before you begin
(Optional) Configure subinterfaces.
For the management interface, you can use a static
address or you can use DHCP. If you are using static IP addresses and
connecting remotely to the management interface using SSH, the current IP address of
prospective data nodes are for temporary use.
Each member will be assigned an IP address from
the cluster IP pool defined on the control node.
The cluster IP pool cannot include addresses
already in use on the network, including prospective secondary IP
addresses.
For example:
You configure the control node to use 10.1.1.1.
Other nodes use 10.1.1.2, 10.1.1.3, and 10.1.1.4.
When you configure the cluster IP pool on the control node,
you cannot include the .2, .3, or .4 addresses in the pool,
because they are in use.
Instead, you need to use other IP addresses on the network,
such as .5, .6, .7, and .8.
Note
The pool needs as many addresses as
there are members of the cluster, including the control
node; the original .1 address is the main cluster IP
address that belongs to the current control node.
After you join the cluster, the old, temporary addresses are
relinquished and can be used elsewhere.
Procedure
Step 1
Configure a pool of Local IP addresses (IPv4 and/or
IPv6), one of which will be assigned to each cluster node for the interface:
(IPv4)
ip local poolpoolnamefirst-address—last-address [maskmask]
(IPv6)
ipv6 local poolpoolnameipv6-address/prefix-lengthnumber_of_addresses
Example:
ciscoasa(config)# ip local pool ins 192.168.1.2-192.168.1.9
ciscoasa(config-if)# ipv6 local pool insipv6 2001:DB8:45:1003/64 8
Include at least as many addresses as there are nodes
in the cluster. If you plan to expand the cluster, include additional
addresses. The Main cluster IP address that belongs to the current control
node is not a part of this pool; be sure to
reserve an IP address on the same network for the Main cluster IP address.
You cannot determine the exact Local address assigned
to each node in advance; to see the address used on each node, enter the show ip[v6] local pool poolname
command. Each cluster member is assigned a member ID when it joins the
cluster. The ID determines the Local IP used from the pool.
Step 2
Enter interface configuration mode:
interfaceinterface_id
Example:
ciscoasa(config)# interface gigabitethernet 0/1
Step 3
Name the interface:
nameifname
Example:
ciscoasa(config-if)# nameif inside
The name is a text string
up to 48 characters, and is not case-sensitive. You can change the name by
reentering this command with a new value.
Step 4
Set the Main cluster IP address and identify the cluster
pool:
ciscoasa(config-if)# ip address 192.168.1.1 255.255.255.0 cluster-pool ins
ciscoasa(config-if)# ipv6 address 2001:DB8:45:1003::99/64 cluster-pool insipv6
This IP address must be on the same network as the
cluster pool addresses, but not be part of the pool. You can configure an
IPv4 and/or an IPv6 address.
DHCP, PPPoE, and IPv6 autoconfiguration are not
supported; you must manually configure the IP addresses. Manually
configuring the link-local address is also not supported.
Step 5
Set the security level, where number is an integer between 0 (lowest) and 100 (highest):
security-levelnumber
Example:
ciscoasa(config-if)# security-level 100
Step 6
Enable the interface:
noshutdown
Examples
The following example configures the Management 0/0,
GigabitEthernet 0/0, and GigabitEthernet 0/1 interfaces as Individual interfaces:
ip local pool mgmt 10.1.1.2-10.1.1.9
ipv6 local pool mgmtipv6 2001:DB8:45:1002/64 8
interface management 0/0
nameif management
ip address 10.1.1.1 255.255.255.0 cluster-pool mgmt
ipv6 address 2001:DB8:45:1001::99/64 cluster-pool mgmtipv6
security-level 100
no shutdown
ip local pool out 209.165.200.225-209.165.200.232
ipv6 local pool outipv6 2001:DB8:45:1002/64 8
interface gigabitethernet 0/0
nameif outside
ip address 209.165.200.233 255.255.255.224 cluster-pool out
ipv6 address 2001:DB8:45:1002::99/64 cluster-pool outipv6
security-level 0
no shutdown
ip local pool ins 192.168.1.2-192.168.1.9
ipv6 local pool insipv6 2001:DB8:45:1003/64 8
interface gigabitethernet 0/1
nameif inside
ip address 192.168.1.1 255.255.255.0 cluster-pool ins
ipv6 address 2001:DB8:45:1003::99/64 cluster-pool insipv6
security-level 100
no shutdown
Create the Bootstrap Configuration
Each node in the cluster requires a bootstrap configuration to join the cluster.
Configure Control Node Bootstrap Settings
Each node in the cluster requires a bootstrap configuration to
join the cluster. Typically, the first node you configure to join the cluster will
be the control node. After you enable clustering, after an election period, the
cluster elects a control node. With only one node in the cluster initially, that
node will become the control node. Subsequent nodes that you add to the cluster will
be data nodes.
Before you begin
Back up your configurations in case you later want to leave the cluster, and
need to restore your configuration.
With the exception of the cluster control link and the Management interface,
which can optionally use DHCP, any interfaces in your configuration must be
configured with a cluster IP pool before you enable clustering. If you have
pre-existing interface configuration, you can either clear the interface
configuration (clear configure interface), or
convert your interfaces to cluster interfaces before you enable clustering.
When you add a node to a running cluster, you may see temporary, limited
packet/connection drops; this is expected behavior.
Enable jumbo frame reservation for use with the cluster control link, so you
can set the cluster control link MTU to the recommended value. See the
jumbo-frame reservation command. Enabling
jumbo frames causes the ASA to reload, so you must perform this step before
continuing with this procedure.
Procedure
Step 1
Configure a VXLAN interface for the cluster control link
interface before you join the cluster.
You will later identify this interface as the cluster
control link when you enable clustering.
The cluster control link interface configuration is not
replicated from the control node to data nodes; however, you must use the
same configuration on each node. Because this configuration is not
replicated, you must configure the cluster control link interfaces
separately on each node.
Identify the VTEP peer IP addresses by creating a network object
group.
See the "Objects for Access Control" chapter in the ASA firewall
configuration guide for more information about network object
groups.
The underlying IP network between VTEPs is independent of the cluster
control link network that the VNI interfaces use. Each VTEP source
interface has an IP address on the same subnet. This subnet should
be isolated from all other traffic, and should include only the
cluster control link interfaces.
Example:
The following example creates a network object group with hosts
defined inline:
Specify the maximum transmission unit for the VTEP source interface to
be at least 154 bytes higher than the highest MTU of the data
interfaces.
mtuinterface_namebytes
Because the cluster control link traffic
includes data packet forwarding, the cluster control link needs to
accommodate the entire size of a data packet plus cluster traffic
overhead (100 bytes) and VXLAN overhead (54 bytes). Set the MTU
between 1554 and 9198 bytes, but not between 2561
and 8362. Due to block pool handling, this MTU size is not optimal
for system operation. The default MTU is 1554 bytes. We suggest
setting the cluster control link MTU to 1654 when data interfaces
are set to 1500; this value requires jumbo frame reservation (see
the jumbo-frame reservation command).
For example, when using jumbo frames, because the maximum MTU is 9198
bytes, then the highest data interface MTU can be 9044, while the
cluster control link can be set to 9198.
This command is replicated to data nodes, but we recommend you
configure this setting along with the bootstrap settings.
Example:
ciscoasa(config)# mtu ccl 1654
(Optional) Set the VXLAN UDP port.
vxlanport number
By default, the VTEP source interface accepts
VXLAN traffic to UDP port 4789. If your network uses a non-standard
port, you can change it.
Set the VNI number between 1 and 10000.
This ID is only an internal interface identifier.
Set the segment ID between 1 and
16777215. The segment ID is used for VXLAN tagging.
Do not configure a name for the
interface or any other parameters.
Step 2
Name the cluster and enter cluster configuration mode:
cluster groupname
Example:
ciscoasa(config)# cluster group pod1
The name must be an ASCII string from 1 to 38
characters. You can only configure one cluster group per node. All members
of the cluster must use the same name.
Step 3
Name this member of the cluster:
local-unitnode_name
Use a unique ASCII string from 1 to 38 characters. Each
node must have a unique name. A node with a duplicated name will not be
allowed in the cluster.
Example:
ciscoasa(cfg-cluster)# local-unit node1
Step 4
Specify the cluster control link VNI interface:
cluster-interfacevni_interface_idipip_addressmask
Example:
ciscoasa(cfg-cluster)# cluster-interface vni1 ip 192.168.1.1 255.255.255.0
INFO: Non-cluster interface config is cleared on VNI1
Specify an IPv4 address for the IP address; IPv6 is not
supported for this interface. For each node, specify a different IP address
on the same network. The VNI network is the encrypted virtual network that
runs on top of the physical VTEP network.
Step 5
Set the priority of this node for control node elections:
prioritypriority_number
Example:
ciscoasa(cfg-cluster)# priority 1
The priority is between 1 and 100, where 1 is the
highest priority.
Step 6
(Optional) Set an
authentication key for control traffic on the cluster control link:
keyshared_secret
Example:
ciscoasa(cfg-cluster)# key chuntheunavoidable
The shared secret is an ASCII string from 1 to 63
characters. The shared secret is used to generate the key. This command does
not affect datapath traffic, including connection state update and forwarded
packets, which are always sent in the clear.
Step 7
Enable clustering:
enable [noconfirm]
Example:
ciscoasa(cfg-cluster)# enable
INFO: Clustering is not compatible with following commands:
policy-map global_policy
class inspection_default
inspect skinny
policy-map global_policy
class inspection_default
inspect sip
Would you like to remove these commands? [Y]es/[N]o:Y
INFO: Removing incompatible commands from running configuration...
Cryptochecksum (changed): f16b7fc2 a742727e e40bc0b0 cd169999
INFO: Done
When you enter the enable
command, the ASA scans the running configuration for incompatible commands
for features that are not supported with clustering, including commands that
may be present in the default configuration. You are prompted to delete the
incompatible commands. If you respond No, then
clustering is not enabled. Use the noconfirm
keyword to bypass the confirmation and delete incompatible commands
automatically.
For the first node enabled, a control node election
occurs. Because the first node should be the only member of the cluster so
far, it will become the control node. Do not perform any configuration
changes during this period.
To disable clustering, enter the no enable command.
Note
If you disable clustering, all data interfaces are
shut down, and only the management interface is active.
Examples
The following example configures the management, inside, and
outside interfaces and the VXLAN cluster control link, and then enables clustering
for the ASA called “node1,” which will become the control node because it is added
to the cluster first:
ip local pool mgmt 10.1.1.2-10.1.1.9
ipv6 local pool mgmtipv6 2001:DB8:45:1002/64 8
interface management 0/0
nameif management
ip address 10.1.1.1 255.255.255.0 cluster-pool mgmt
ipv6 address 2001:DB8:45:1001::99/64 cluster-pool mgmtipv6
security-level 100
no shutdown
ip local pool out 209.165.200.225-209.165.200.232
ipv6 local pool outipv6 2001:DB8:45:1002/64 8
interface gigabitethernet 0/0
nameif outside
ip address 209.165.200.233 255.255.255.224 cluster-pool out
ipv6 address 2001:DB8:45:1002::99/64 cluster-pool outipv6
security-level 0
no shutdown
ip local pool ins 192.168.1.2-192.168.1.9
ipv6 local pool insipv6 2001:DB8:45:1003/64 8
interface gigabitethernet 0/1
nameif inside
ip address 192.168.1.1 255.255.255.0 cluster-pool ins
ipv6 address 2001:DB8:45:1003::99/64 cluster-pool insipv6
security-level 100
no shutdown
object-group network cluster-peers
network-object host 10.6.6.51
network-object host 10.6.6.52
network-object host 10.6.6.53
network-object host 10.6.6.54
interface gigabitethernet 0/7
nve-only cluster
nameif ccl
ip address 10.6.6.51 255.255.255.0
no shutdown
nve 1
source-interface ccl
peer-group cluster-peers
mtu ccl 1654
interface vni 1
segment-id 1000
vtep-nve 1
cluster group pod1
local-unit node1
cluster-interface vni1 ip 192.168.1.1 255.255.255.0
priority 1
key 67impala
enable noconfirm
Configure Data Node Bootstrap Settings
Perform the following procedure to configure the data nodes.
Before you begin
Back up your configurations in case you later want to leave the cluster, and
need to restore your configuration.
With the exception of the cluster control link and the Management interface,
which can optionally use DHCP, any interfaces in your configuration must be
configured with a cluster IP pool before you enable clustering. If you have
pre-existing interface configuration, you can either clear the interface
configuration (clear configure interface), or
convert your interfaces to cluster interfaces before you enable clustering.
When you add a node to a running cluster, you may see temporary, limited
packet/connection drops; this is expected behavior.
Enable jumbo frame reservation for use with the cluster control link, so you
can set the cluster control link MTU to the recommended value. See the
jumbo-frame reservation command. Enabling
jumbo frames causes the ASA to reload, so you must perform this step before
continuing with this procedure.
Procedure
Step 1
Configure the same cluster control link interface as you configured for the
control node. Be sure to supply a different IP address for the VTEP source
interface (shown in bold).
Identify the same cluster name that you configured for the control node:
Example:
ciscoasa(config)# cluster group pod1
Step 3
Name this member of the cluster with a unique string:
local-unitnode_name
Example:
ciscoasa(cfg-cluster)# local-unit node2
Specify an ASCII string from 1 to 38 characters.
Each node must have a unique name. A node with a
duplicated name will be not be allowed in the cluster.
Step 4
Specify the same cluster control link interface that you configured for the
control node, but specify a different IP address on the same network for each
node:
cluster-interfacevni_interface_idipip_addressmask
Example:
ciscoasa(cfg-cluster)# cluster-interface vni1 ip 192.168.1.2 255.255.255.0
INFO: Non-cluster interface config is cleared on VNI1
Specify an IPv4 address for the IP address; IPv6 is not
supported for this interface. This interface cannot have a nameif configured.
Step 5
If you use inter-site clustering, set the site ID for this node so it uses a
site-specific MAC address:
site-idnumber
Example:
ciscoasa(cfg-cluster)# site-id 2
The number is between 1 and 8.
Step 6
Set the priority of this node for control node elections, typically to a higher
value than the control node:
prioritypriority_number
Example:
ciscoasa(cfg-cluster)# priority 2
Set the priority between 1 and 100, where 1 is the
highest priority.
Step 7
Set the same authentication key that you set for the control node:
Example:
ciscoasa(cfg-cluster)# key chuntheunavoidable
Step 8
Enable clustering:
enableas-data-node
You can avoid any configuration incompatibilities
(primarily the existence of any interfaces not yet configured for
clustering) by using the enable as-data-node command. This command ensures the data node joins the
cluster with no possibility of becoming the control node in any current
election. Its configuration is overwritten with the one synced from the
control node.
To disable clustering, enter the no enable command.
Note
If you disable clustering, all data interfaces are
shut down, and only the management interface is active.
Examples
The following example includes the configuration for a data
node, node2:
You can customize clustering health monitoring, TCP connection replication delay, flow
mobility and other optimizations, either as part of the Day 0 configuration or after you
deploy the cluster.
Perform these procedures on the control node.
Configure Basic ASA Cluster Parameters
You can customize cluster settings on the control node.
Procedure
Step 1
Enter cluster configuration mode:
cluster groupname
Step 2
(Optional) Enable console replication from data nodes to the control node:
console-replicate
This feature is disabled by default. The ASA prints out some messages
directly to the console for certain critical events. If you enable console
replication, data nodes send the console messages to the control node so
that you only need to monitor one console port for the cluster.
Step 3
Set the minimum trace level for clustering events:
trace-levellevel
Set the minimum level as desired:
critical—Critical events (severity=1)
warning—Warnings (severity=2)
informational—Informational events
(severity=3)
debug—Debugging events (severity=4)
Configure Health Monitoring and Auto-Rejoin
Settings
This procedure configures node and interface health monitoring.
You might want to disable health monitoring of non-essential interfaces, for example,
the management interface. Health monitoring is not performed on VLAN subinterfaces.
You cannot configure monitoring for the cluster control link; it is always
monitored.
Procedure
Step 1
Enter cluster configuration mode.
cluster groupname
Example:
ciscoasa(config)# cluster group test
ciscoasa(cfg-cluster)#
Step 2
Customize the cluster node health check feature.
health-check [holdtimetimeout]
To determine node health, the ASA cluster nodes send heartbeat messages on
the cluster control link to other nodes. If a node does not receive any
heartbeat messages from a peer node within the holdtime period, the peer
node is considered unresponsive or dead.
holdtimetimeout—Determines the amount of time between
node heartbeat status messages, between .3 and 45 seconds; The
default is 3 seconds.
When any topology changes occur (such as adding or removing a data interface,
enabling or disabling an interface on the ASA or the switch) you should
disable the health check feature and also disable interface monitoring for
the disabled interfaces (no health-check
monitor-interface). When the topology change is complete,
and the configuration change is synced to all nodes, you can re-enable the
health check feature.
Example:
ciscoasa(cfg-cluster)# health-check holdtime 5
Step 3
Disable the interface health check on an interface.
nohealth-checkmonitor-interfaceinterface_id
The interface health check monitors for link failures.
The amount of time before the ASA removes a member from the cluster depends
on whether the node is an established member or is joining the cluster.
Health check is enabled by default for all interfaces. You can disable it
per interface using the no form of this
command. You might want to disable health monitoring of non-essential
interfaces, for example, the management interface.
interface_id—Disables monitoring of an
interface. Health monitoring is not performed on VLAN subinterfaces.
You cannot configure monitoring for the cluster control link; it is
always monitored.
When any topology changes occur (such as adding or removing a data interface,
enabling or disabling an interface on the ASA or the switch) you should
disable the health check feature (no health-check)
and also disable interface monitoring for the disabled interfaces. When the
topology change is complete, and the configuration change is synced to all
nodes, you can re-enable the health check feature.
Example:
ciscoasa(cfg-cluster)# no health-check monitor-interface management1/1
Step 4
Customize the auto-rejoin cluster settings after a health check failure.
system—Specifies the auto-rejoin settings
for internal errors. Internal failures include: application sync
timeout; inconsistent application statuses; and so on.
unlimited—(Default for the
cluster-interface) Does not limit
the number of rejoin attempts.
auto-rejoin-max—Sets the number of rejoin
attempts, between 0 and 65535. 0 disables
auto-rejoining. The default for the
data-interface and
system is 3.
auto_rejoin_interval—Defines the interval
duration in minutes between rejoin attempts, between 2 and 60. The
default value is 5 minutes. The maximum total time that the node
attempts to rejoin the cluster is limited to 14400 minutes (10 days)
from the time of last failure.
auto_rejoin_interval_variation—Defines if
the interval duration increases. Set the value between 1 and 3:
1 (no change);
2 (2 x the previous duration), or
3 (3 x the previous duration). For
example, if you set the interval duration to 5 minutes, and set the
variation to 2, then the first attempt is after 5 minutes; the 2nd
attempt is 10 minutes (2 x 5); the 3rd attempt 20 minutes (2 x 10),
and so on. The default value is 1 for the
cluster-interface and 2 for the
data-interface and system.
Set the debounce time between 300 and 9000 ms. The default is 500 ms. Lower
values allow for faster detection of interface failures. Note that
configuring a lower debounce time increases the chances of false-positives.
When an interface status update occurs, the ASA waits the number of
milliseconds specified before marking the interface as failed and the node
is removed from the cluster.
frequencyseconds—Sets the time in seconds between
monitoring messages, between 10 and 360 seconds. The default is 20
seconds.
intervalsintervals—Sets the number of intervals for
which the ASA maintains data, between 1 and 60. The default is
30.
You can monitor the traffic load for cluster members, including total
connection count, CPU and memory usage, and buffer drops. If the load is too
high, you can choose to manually disable clustering on the node if the
remaining nodes can handle the load, or adjust the load balancing on the
external switch. This feature is enabled by default. You can periodically
monitor the traffic load. If the load is too high, you can choose to
manually disable clustering on the node.
Use the show cluster info load-monitor command to
view the traffic load.
Example:
ciscoasa(cfg-cluster)# load-monitor frequency 50 intervals 25
ciscoasa(cfg-cluster)# show cluster info load-monitor
ID Unit Name
0 B
1 A_1
Information from all units with 50 second interval:
Unit Connections Buffer Drops Memory Used CPU Used
Average from last 1 interval:
0 0 0 14 25
1 0 0 16 20
Average from last 25 interval:
0 0 0 12 28
1 0 0 13 27
Example
The following example configures the health-check holdtime to .3 seconds; disables
monitoring on the Management 0/0 interface; sets the auto-rejoin for data interfaces
to 4 attempts starting at 2 minutes, increasing the duration by 3 x the previous
interval; and sets the auto-rejoin for the cluster control link to 6 attempts every
2 minutes.
ciscoasa(config)# cluster group test
ciscoasa(cfg-cluster)# health-check holdtime .3
ciscoasa(cfg-cluster)# no health-check monitor-interface management0/0
ciscoasa(cfg-cluster)# health-check data-interface auto-rejoin 4 2 3
ciscoasa(cfg-cluster)# health-check cluster-interface auto-rejoin 6 2 1
Configure Connection Rebalancing and the Cluster TCP Replication Delay
You can configure connection rebalancing. If the load balancing capabilities of the
upstream or downstream routers result in unbalanced flow distribution, you can
configure overloaded nodes to redirect new TCP flows to other nodes. No existing
flows will be moved to other nodes.
Enable the cluster replication delay for TCP connections to help eliminate the
“unnecessary work” related to short-lived flows by delaying the director/backup flow
creation. Note that if a node fails before the director/backup flow is created, then
those flows cannot be recovered. Similarly, if traffic is rebalanced to a different
node before the flow is created, then the flow cannot be recovered. You should not
enable the TCP replication delay for traffic on which you disable TCP
randomization.
Procedure
Step 1
Enable the cluster replication delay for TCP connections:
ciscoasa(config)# cluster replication delay 15 match tcp any any eq ftp
ciscoasa(config)# cluster replication delay 15 http
Set the seconds between 1 and 15. The
http delay is enabled by default for 5
seconds.
Step 2
Enter cluster configuration mode:
cluster groupname
Step 3
(Optional) Enable
connection rebalancing for TCP traffic:
conn-rebalance [frequencyseconds]
Example:
ciscoasa(cfg-cluster)# conn-rebalance frequency 60
This command is disabled by default. If enabled, ASAs
exchange information about the connections per second periodically, and
offload new connections from devices with more connections per second to
less loaded devices. Existing connections are never moved. Moreover, because
this command only rebalances based on connections per second, the total
number of established connections on each node is not considered, and the
total number of connections may not be equal. The frequency, between 1 and
360 seconds, specifies how often the load information is exchanged. The
default is 5 seconds.
Once a connection is offloaded to a different node, it becomes an asymmetric
connection.
Do not configure connection rebalancing for inter-site topologies; you do not
want connections rebalanced to cluster members at a different site.
Configure Inter-Site Features
For inter-site clustering, you can customize your configuration to enhance redundancy and
stability.
Enable Director Localization
To improve performance and reduce round-trip time latency for inter-site clustering
for data centers, you can enable director localization. New connections are
typically load-balanced and owned by cluster members within a given site. However,
the ASA assigns the director role to a member at any site. Director
localization enables additional director roles: a local director at the same site as
the owner, and a global director that can be at any site. Keeping the owner and
director at the same site improves performance. Also, if the original owner fails,
the local director chooses a new connection owner at the same site. The global
director is used if a cluster member receives packets for a connection that is owned
on a different site.
Before you begin
Set the site ID for the cluster member in the bootstrap configuration.
The following traffic types do not support localization: NAT or PAT traffic;
SCTP-inspected traffic; Fragmentation owner query.
Procedure
Step 1
Enter cluster configuration mode.
cluster groupname
Example:
ciscoasa(config)# cluster group cluster1
ciscoasa(cfg-cluster)#
Step 2
Enable director localization.
director-localization
Enable Site Redundancy
To protect flows from a site failure, you can enable site redundancy. If the
connection backup owner is at the same site as the owner, then an additional backup
owner will be chosen from another site to protect flows from a site failure.
Before you begin
Set the site ID for the cluster member in the bootstrap configuration.
Procedure
Step 1
Enter cluster configuration mode.
cluster groupname
Example:
ciscoasa(config)# cluster group cluster1
ciscoasa(cfg-cluster)#
Step 2
Enable site redundancy.
site-redundancy
Configure Cluster Flow Mobility
You can inspect LISP traffic to enable flow mobility when a server moves between
sites.
About LISP Inspection
You can inspect LISP traffic to enable flow mobility between sites.
About LISP
Data center
virtual machine mobility such as VMware VMotion enables servers to migrate
between data centers while maintaining connections to clients. To support such
data center server mobility, routers need to be able to update the ingress
route towards the server when it moves. Cisco Locator/ID Separation Protocol
(LISP) architecture separates the device identity, or endpoint identifier
(EID), from its location, or routing locator (RLOC), into two different
numbering spaces, making server migration transparent to clients. For example,
when a server moves to a new site and a client sends traffic to the server, the
router redirects traffic to the new location.
LISP requires
routers and servers in certain roles, such as the LISP egress tunnel router
(ETR), ingress tunnel router (ITR), first hop routers, map resolver (MR), and
map server (MS). When the first hop router for the server senses that the
server is connected to a different router, it updates all of the other routers
and databases so that the ITR connected to the client can intercept,
encapsulate, and send traffic to the new server location.
ASA LISP Support
The ASA does not run LISP itself; it can, however, inspect LISP traffic for location
changes and then use this information for seamless clustering operation. Without
LISP integration, when a server moves to a new site, traffic comes to an ASA cluster member at the new site instead of to the original flow owner. The new
ASA forwards traffic to the ASA at the old site, and then the old ASA has to send traffic back to the new site to reach the server. This traffic
flow is sub-optimal and is known as “tromboning” or “hair-pinning.”
With LISP integration, the ASA cluster members can inspect LISP traffic passing between the first hop router
and the ETR or ITR, and can then change the flow owner to be at the new site.
LISP Guidelines
The ASA cluster members must reside between the first hop router and the ITR
or ETR for the site. The ASA cluster itself cannot be the first hop router for an extended
segment.
Only fully-distributed flows are supported; centralized flows, semi-distributed flows, or
flows belonging to individual nodes are not moved to new owners.
Semi-distributed flows include applications, such as SIP, where all
child flows are owned by the same ASA that owns the parent flow.
The cluster
only moves Layer 3 and 4 flow states; some application data might be lost.
For
short-lived flows or non-business-critical flows, moving the owner may not be
worthwhile. You can control the types of traffic that are supported with this
feature when you configure the inspection policy, and should limit flow
mobility to essential traffic.
ASA LISP Implementation
This feature
includes several inter-related configurations (all of which are described in
this chapter):
(Optional) Limit inspected EIDs based on the host or server IP address—The first hop router
might send EID-notify messages for hosts or networks the ASA cluster is not involved with, so you can limit the EIDs to only those
servers or networks relevant to your cluster. For example, if the
cluster is only involved with 2 sites, but LISP is running on 3 sites,
you should only include EIDs for the 2 sites involved with the cluster.
LISP traffic inspection—The ASA inspects LISP traffic on UDP port 4342 for the EID-notify message
sent between the first hop router and the ITR or ETR. The ASA maintains an EID table that correlates the EID and the site ID. For
example, you should inspect LISP traffic with a source IP address of the
first hop router and a destination address of the ITR or ETR. Note that
LISP traffic is not assigned a director, and LISP traffic itself does
not participate in cluster state sharing.
Service Policy
to enable flow mobility on specified traffic—You should enable flow mobility on
business-critical traffic. For example, you can limit flow mobility to only
HTTPS traffic, and/or to traffic to specific servers.
Site IDs—The ASA uses the site ID for each cluster node to determine the new owner.
Cluster-level
configuration to enable flow mobility—You must also enable flow mobility at the
cluster level. This on/off toggle lets you easily enable or disable flow
mobility for a particular class of traffic or applications.
Configure LISP Inspection
You can inspect LISP traffic to enable flow mobility when a server moves between
sites.
LISP traffic is not included in the default-inspection-traffic class, so you
must configure a separate class for LISP traffic as part of this procedure.
SUMMARY STEPS
(Optional) Configure a LISP inspection map to limit inspected EIDs based on IP address,
and to configure the LISP pre-shared key:
Configure LISP inspection for UDP traffic between the first hop router and the
ITR or ETR on port 4342:
Enable Flow Mobility for a traffic class:
Enter cluster group configuration mode, and enable flow mobility for the
cluster:
DETAILED STEPS
Step 1
(Optional) Configure a LISP inspection map to limit inspected EIDs based on IP address,
and to configure the LISP pre-shared key:
Create an extended ACL; only the destination IP address is matched to
the EID embedded address:
Both IPv4 and IPv6 ACLs are accepted. See the command reference for
exact access-list extended syntax.
Create the LISP inspection map, and enter parameters mode:
policy-map type inspect lispinspect_map_name
parameters
Define the allowed EIDs by identifying the ACL you created:
allowed-eid access-listeid_acl_name
The first hop router or ITR/ETR might send EID-notify messages for
hosts or networks that the ASA cluster is not involved with, so you
can limit the EIDs to only those servers or networks relevant to
your cluster. For example, if the cluster is only involved with 2
sites, but LISP is running on 3 sites, you should only include EIDs
for the 2 sites involved with the cluster.
If necessary, enter the pre-shared key:
validate-keykey
Example:
ciscoasa(config)# access-list TRACKED_EID_LISP extended permit ip any 10.10.10.0 255.255.255.0
ciscoasa(config)# policy-map type inspect lisp LISP_EID_INSPECT
ciscoasa(config-pmap)# parameters
ciscoasa(config-pmap-p)# allowed-eid access-list TRACKED_EID_LISP
ciscoasa(config-pmap-p)# validate-key MadMaxShinyandChrome
Step 2
Configure LISP inspection for UDP traffic between the first hop router and the
ITR or ETR on port 4342:
Configure the extended ACL to identify LISP traffic:
You must specify UDP port 4342. Both IPv4 and IPv6 ACLs are
accepted. See the command reference for exact
access-list extended syntax.
Create a class map for the ACL:
class-mapinspect_class_name
match access-listinspect_acl_name
Specify the policy map, the class map, enable inspection using the
optional LISP inspection map, and apply the service policy to an
interface (if new):
If you have an existing service policy, specify the existing policy
map name. By default, the ASA includes a global policy called
global_policy, so for a global policy, specify that name.
You can also create one service policy per interface if you do not
want to apply the policy globally. LISP inspection is applied to
traffic bidirectionally so you do not need to apply the service
policy on both the source and destination interfaces; all traffic
that enters or exits the interface to which you apply the policy map
is affected if the traffic matches the class map for both
directions.
The ASA inspects LISP traffic for the EID-notify message sent between the
first hop router and the ITR or ETR. The ASA maintains an EID table that
correlates the EID and the site ID.
Step 3
Enable Flow Mobility for a traffic class:
Configure the extended ACL to identify business critical traffic that
you want to re-assign to the most optimal site when servers change
sites:
Both IPv4 and IPv6 ACLs are accepted. See the command reference for
exact access-list extended syntax. You
should enable flow mobility on business-critical traffic. For
example, you can limit flow mobility to only HTTPS traffic, and/or
to traffic to specific servers.
Create a class map for the ACL:
class-mapflow_map_name
match access-listflow_acl_name
Specify the same policy map on which you enabled LISP inspection, the
flow class map, and enable flow mobility:
policy-mappolicy_map_name
classflow_map_name
cluster flow-mobility lisp
Example:
ciscoasa(config)# access-list IMPORTANT-FLOWS extended permit tcp any 10.10.10.0 255.255.255.0 eq https
ciscoasa(config)# class-map IMPORTANT-FLOWS-MAP
ciscoasa(config)# match access-list IMPORTANT-FLOWS
ciscoasa(config-cmap)# policy-map INSIDE_POLICY
ciscoasa(config-pmap)# class IMPORTANT-FLOWS-MAP
ciscoasa(config-pmap-c)# cluster flow-mobility lisp
Step 4
Enter cluster group configuration mode, and enable flow mobility for the
cluster:
cluster groupname
flow-mobility lisp
This on/off toggle lets you easily enable or disable flow mobility.
Examples
The following example:
Limits EIDs to those on the 10.10.10.0/24 network
Inspects LISP traffic (UDP 4342) between a LISP router at 192.168.50.89 (on
inside) and an ITR or ETR router (on another ASA interface) at 192.168.10.8
Enables flow mobility for all inside traffic going to a server on
10.10.10.0/24 using HTTPS.
Enables flow mobility for the cluster.
access-list TRACKED_EID_LISP extended permit ip any 10.10.10.0 255.255.255.0
policy-map type inspect lisp LISP_EID_INSPECT
parameters
allowed-eid access-list TRACKED_EID_LISP
validate-key MadMaxShinyandChrome
!
access-list LISP_ACL extended permit udp host 192.168.50.89 host 192.168.10.8 eq 4342
class-map LISP_CLASS
match access-list LISP_ACL
policy-map INSIDE_POLICY
class LISP_CLASS
inspect lisp LISP_EID_INSPECT
service-policy INSIDE_POLICY interface inside
!
access-list IMPORTANT-FLOWS extended permit tcp any 10.10.10.0 255.255.255.0 eq https
class-map IMPORTANT-FLOWS-MAP
match access-list IMPORTANT-FLOWS
policy-map INSIDE_POLICY
class IMPORTANT-FLOWS-MAP
cluster flow-mobility lisp
!
cluster group cluster1
flow-mobility lisp
Manage Cluster Nodes
After you deploy the cluster, you can change the configuration and
manage cluster nodes.
Become an Inactive Node
To become an inactive member of the cluster, disable clustering
on the node while leaving the clustering configuration intact.
Note
When an ASA becomes inactive (either manually or through a
health check failure), all data interfaces are shut down; only the
management-only interface can send and receive traffic. To resume traffic flow,
re-enable clustering; or you can remove the node altogether from the cluster.
The management interface remains up using the IP address the node received from
the cluster IP pool. However if you reload, and the node is still inactive in
the cluster (for example, you saved the configuration with clustering disabled),
then the management interface is disabled. You must use the console port for any
further configuration.
Procedure
Step 1
Enter cluster configuration mode:
cluster groupname
Example:
ciscoasa(config)# cluster group pod1
Step 2
Disable clustering:
noenable
If this node was the control node, a new control
election takes place, and a different member becomes the control node.
The cluster configuration is maintained, so that you
can enable clustering again later.
Deactivate a Data Node from the Control Node
To deactivate a member other than the node you are logged into, perform
the following steps.
Note
When an ASA becomes inactive, all data interfaces are shut
down; only the management-only interface can send and receive traffic. To resume
traffic flow, re-enable clustering. The management interface remains up using
the IP address the node received from the cluster IP pool. However if you
reload, and the node is still inactive in the cluster (for example, if you saved
the configuration with clustering disabled), the management interface is
disabled. You must use the console port for any further configuration.
Procedure
Remove the node from the cluster.
cluster removeunitnode_name
The bootstrap configuration remains intact, as well as
the last configuration synched from the control node, so that you can later
re-add the node without losing your configuration. If you enter this command
on a data node to remove the control node, a new control node is elected.
To view member names, enter cluster remove unit ?, or enter the show
cluster info command.
Example:
ciscoasa(config)# cluster remove unit ?
Current active units in the cluster:
asa2
ciscoasa(config)# cluster remove unit asa2
WARNING: Clustering will be disabled on unit asa2. To bring it back
to the cluster please logon to that unit and re-enable clustering
Rejoin the Cluster
If a node was removed from the cluster, for example for a failed interface or if you
manually deactivated a member, you must manually rejoin the cluster.
Procedure
Step 1
At the
console, enter cluster configuration mode:
cluster groupname
Example:
ciscoasa(config)# cluster group pod1
Step 2
Enable clustering.
enable
Leave the Cluster
If you want to leave the cluster altogether, you need to remove
the entire cluster bootstrap configuration. Because the current configuration on
each node is the same (synced from the active unit), leaving the cluster also means
either restoring a pre-clustering configuration from backup, or clearing your
configuration and starting over to avoid IP address conflicts.
Procedure
Step 1
For a data node, disable clustering:
cluster groupcluster_name no enable
Example:
ciscoasa(config)# cluster group cluster1
ciscoasa(cfg-cluster)# no enable
You cannot make configuration changes while clustering
is enabled on a data node.
Step 2
Clear the cluster configuration:
clear configure cluster
The ASA shuts down all interfaces including the
management interface and cluster control link.
Step 3
Disable cluster interface mode:
no cluster interface-mode
The mode is not stored in the configuration and must be
reset manually.
Step 4
If you have a backup configuration, copy the backup
configuration to the running configuration:
If you do not have a backup configuration, reconfigure
management access. Be sure to change the interface IP addresses, and restore the
correct hostname, for example.
Change the Control Node
Caution
The best method to change the control node is to disable
clustering on the control node, wait for a new control election, and then
re-enable clustering. If you must specify the exact node you want to become the
control node, use the procedure in this section. Note, however, that for
centralized features, if you force a control node change using this procedure,
then all connections are dropped, and you have to re-establish the connections
on the new control node.
To change the control node, perform the following steps.
Procedure
Set a new node as the control node:
clustercontrol-nodeunitnode_name
Example:
ciscoasa(config)# cluster control-node unit asa2
You will need to reconnect to the Main cluster IP
address.
To view member names, enter cluster control-node unit ? (to see
all names except the current node), or enter the show cluster info command.
Execute a Command Cluster-Wide
To send a command to all nodes in the cluster, or to a specific
node, perform the following steps. Sending a show
command to all nodes collects all output and displays it on the console of the
current node. Other commands, such as capture and copy, can also take advantage of cluster-wide
execution.
Procedure
Send a command to all nodes, or if you specify the node
name, a specific node:
cluster exec [unitnode_name] command
Example:
ciscoasa# cluster exec show xlate
To view node names, enter cluster exec unit ? (to see all names except the current node), or
enter the show cluster info command.
Examples
To copy the same capture file from all nodes in the cluster at
the same time to a TFTP server, enter the following command on the control node:
Multiple PCAP files, one from each node, are copied to the TFTP
server. The destination capture file name is automatically attached with the node
name, such as capture1_asa1.pcap, capture1_asa2.pcap, and so on. In this example,
asa1 and asa2 are cluster node names.
Monitoring the ASA
Virtual Cluster
You can monitor and troubleshoot cluster status and
connections.
Monitoring Cluster Status
See the following
commands for monitoring cluster
status:
show cluster info [health[details]]
With no keywords, the show cluster
info command shows the status of all members of the cluster.
The show cluster info health command
shows the current health of interfaces, nodes, and the cluster overall. The details keyword shows the number heartbeat message
failures.
See the following output for the show
cluster info command:
ciscoasa# show cluster info
Cluster stbu: On
This is "C" in state DATA_NODE
ID : 0
Site ID : 1
Version : 9.4(1)
Serial No.: P3000000025
CCL IP : 10.0.0.3
CCL MAC : 000b.fcf8.c192
Last join : 17:08:59 UTC Sep 26 2011
Last leave: N/A
Other members in the cluster:
Unit "D" in state DATA_NODE
ID : 1
Site ID : 1
Version : 9.4(1)
Serial No.: P3000000001
CCL IP : 10.0.0.4
CCL MAC : 000b.fcf8.c162
Last join : 19:13:11 UTC Sep 23 2011
Last leave: N/A
Unit "A" in state CONTROL_NODE
ID : 2
Site ID : 2
Version : 9.4(1)
Serial No.: JAB0815R0JY
CCL IP : 10.0.0.1
CCL MAC : 000f.f775.541e
Last join : 19:13:20 UTC Sep 23 2011
Last leave: N/A
Unit "B" in state DATA_NODE
ID : 3
Site ID : 2
Version : 9.4(1)
Serial No.: P3000000191
CCL IP : 10.0.0.2
CCL MAC : 000b.fcf8.c61e
Last join : 19:13:50 UTC Sep 23 2011
Last leave: 19:13:36 UTC Sep 23 2011
show cluster info auto-join
Shows whether the cluster node will automatically rejoin the cluster after a time delay
and if the failure conditions (such as waiting for the license, chassis health check
failure, and so on) are cleared. If the node is permanently disabled, or if the node is
already in the cluster, then this command will not show any output.
See the following outputs for the show cluster info auto-join command:
ciscoasa(cfg-cluster)# show cluster info auto-join
Unit will try to join cluster in 253 seconds.
Quit reason: Received control message DISABLE
ciscoasa(cfg-cluster)# show cluster info auto-join
Unit will try to join cluster when quit reason is cleared.
Quit reason: Control node has application down that data node has up.
ciscoasa(cfg-cluster)# show cluster info auto-join
Unit will try to join cluster when quit reason is cleared.
Quit reason: Chassis-blade health check failed.
ciscoasa(cfg-cluster)# show cluster info auto-join
Unit will try to join cluster when quit reason is cleared.
Quit reason: Service chain application became down.
ciscoasa(cfg-cluster)# show cluster info auto-join
Unit will try to join cluster when quit reason is cleared.
Quit reason: Unit is kicked out from cluster because of Application health check failure.
ciscoasa(cfg-cluster)# show cluster info auto-join
Unit join is pending (waiting for the smart license entitlement: ent1)
ciscoasa(cfg-cluster)# show cluster info auto-join
Unit join is pending (waiting for the smart license export control flag)
show cluster info transport {asp | cp [detail]}
Shows transport related statistics for the following:
asp —Data plane transport statistics.
cp —Control plane transport statistics.
If you enter the detail keyword,
you can view cluster reliable transport protocol usage so you can identify packet
drop issues when the buffer is full in the control plane. See the following output
for the show cluster info transport cp detail command:
ciscoasa# show cluster info transport cp detail
Member ID to name mapping:
0 - unit-1-1 2 - unit-4-1 3 - unit-2-1
Legend:
U - unreliable messages
UE - unreliable messages error
SN - sequence number
ESN - expecting sequence number
R - reliable messages
RE - reliable messages error
RDC - reliable message deliveries confirmed
RA - reliable ack packets received
RFR - reliable fast retransmits
RTR - reliable timer-based retransmits
RDP - reliable message dropped
RDPR - reliable message drops reported
RI - reliable message with old sequence number
RO - reliable message with out of order sequence number
ROW - reliable message with out of window sequence number
ROB - out of order reliable messages buffered
RAS - reliable ack packets sent
This unit as a sender
--------------------------
all 0 2 3
U 123301 3867966 3230662 3850381
UE 0 0 0 0
SN 1656a4ce acb26fe 5f839f76 7b680831
R 733840 1042168 852285 867311
RE 0 0 0 0
RDC 699789 934969 740874 756490
RA 385525 281198 204021 205384
RFR 27626 56397 0 0
RTR 34051 107199 111411 110821
RDP 0 0 0 0
RDPR 0 0 0 0
This unit as a receiver of broadcast messages
---------------------------------------------
0 2 3
U 111847 121862 120029
R 7503 665700 749288
ESN 5d75b4b3 6d81d23 365ddd50
RI 630 34278 40291
RO 0 582 850
ROW 0 566 850
ROB 0 16 0
RAS 1571 123289 142256
This unit as a receiver of unicast messages
---------------------------------------------
0 2 3
U 1 3308122 4370233
R 513846 879979 1009492
ESN 4458903a 6d841a84 7b4e7fa7
RI 66024 108924 102114
RO 0 0 0
ROW 0 0 0
ROB 0 0 0
RAS 130258 218924 228303
Gated Tx Buffered Message Statistics
-------------------------------------
current sequence number: 0
total: 0
current: 0
high watermark: 0
delivered: 0
deliver failures: 0
buffer full drops: 0
message truncate drops: 0
gate close ref count: 0
num of supported clients:45
MRT Tx of broadcast messages
=============================
Message high watermark: 3%
Total messages buffered at high watermark: 5677
[Per-client message usage at high watermark]
---------------------------------------------------------------
Client name Total messages Percentage
Cluster Redirect Client 4153 73%
Route Cluster Client 419 7%
RRI Cluster Client 1105 19%
Current MRT buffer usage: 0%
Total messages buffered in real-time: 1
[Per-client message usage in real-time]
Legend:
F - MRT messages sending when buffer is full
L - MRT messages sending when cluster node leave
R - MRT messages sending in Rx thread
----------------------------------------------------------------------------
Client name Total messages Percentage F L R
VPN Clustering HA Client 1 100% 0 0 0
MRT Tx of unitcast messages(to member_id:0)
============================================
Message high watermark: 31%
Total messages buffered at high watermark: 4059
[Per-client message usage at high watermark]
---------------------------------------------------------------
Client name Total messages Percentage
Cluster Redirect Client 3731 91%
RRI Cluster Client 328 8%
Current MRT buffer usage: 29%
Total messages buffered in real-time: 3924
[Per-client message usage in real-time]
Legend:
F - MRT messages sending when buffer is full
L - MRT messages sending when cluster node leave
R - MRT messages sending in Rx thread
----------------------------------------------------------------------------
Client name Total messages Percentage F L R
Cluster Redirect Client 3607 91% 0 0 0
RRI Cluster Client 317 8% 0 0 0
MRT Tx of unitcast messages(to member_id:2)
============================================
Message high watermark: 14%
Total messages buffered at high watermark: 578
[Per-client message usage at high watermark]
---------------------------------------------------------------
Client name Total messages Percentage
VPN Clustering HA Client 578 100%
Current MRT buffer usage: 0%
Total messages buffered in real-time: 0
MRT Tx of unitcast messages(to member_id:3)
============================================
Message high watermark: 12%
Total messages buffered at high watermark: 573
[Per-client message usage at high watermark]
---------------------------------------------------------------
Client name Total messages Percentage
VPN Clustering HA Client 572 99%
Cluster VPN Unique ID Client 1 0%
Current MRT buffer usage: 0%
Total messages buffered in real-time: 0
show cluster history
Shows the cluster history, as
well as error messages about why a cluster node failed to join or why a node left the
cluster.
Capturing Packets Cluster-Wide
See the following
command for capturing
packets in a cluster:
cluster exec capture
To support cluster-wide troubleshooting, you can enable capture of
cluster-specific traffic on the control node using the cluster exec capture command, which is
then automatically enabled on all of the data nodes in the cluster.
Monitoring Cluster Resources
See the following command for monitoring
cluster resources:
show cluster {cpu | memory | resource} [options]
Displays aggregated data for the entire cluster. The
options available depends on the data type.
Monitoring Cluster Traffic
See the following commands
for monitoring cluster traffic:
show conn
[detail], cluster exec show conn
The show conn
command shows whether a flow is a director, backup, or
forwarder flow. Use the cluster
exec show conn command on any node to view all
connections. This command can show how traffic for a single
flow arrives at different ASAs in the cluster. The
throughput of the cluster is dependent on the efficiency and
configuration of load balancing. This command provides an
easy way to view how traffic for a connection is flowing
through the cluster, and can help you understand how a load
balancer might affect the performance of a flow.
The show conn detail command also
shows which flows are subject to flow mobility.
The following is sample output for the show conn detail command:
ciscoasa/ASA2/data node# show conn detail
12 in use, 13 most used
Cluster stub connections: 0 in use, 46 most used
Flags: A - awaiting inside ACK to SYN, a - awaiting outside ACK to SYN,
B - initial SYN from outside, b - TCP state-bypass or nailed,
C - CTIQBE media, c - cluster centralized,
D - DNS, d - dump, E - outside back connection, e - semi-distributed,
F - outside FIN, f - inside FIN,
G - group, g - MGCP, H - H.323, h - H.225.0, I - inbound data,
i - incomplete, J - GTP, j - GTP data, K - GTP t3-response
k - Skinny media, L - LISP triggered flow owner mobility,
M - SMTP data, m - SIP media, n - GUP
O - outbound data, o - offloaded,
P - inside back connection,
Q - Diameter, q - SQL*Net data,
R - outside acknowledged FIN,
R - UDP SUNRPC, r - inside acknowledged FIN, S - awaiting inside SYN,
s - awaiting outside SYN, T - SIP, t - SIP transient, U - up,
V - VPN orphan, W - WAAS,
w - secondary domain backup,
X - inspected by service module,
x - per session, Y - director stub flow, y - backup stub flow,
Z - Scansafe redirection, z - forwarding stub flow
ESP outside: 10.1.227.1/53744 NP Identity Ifc: 10.1.226.1/30604, , flags c, idle 0s, uptime
1m21s, timeout 30s, bytes 7544, cluster sent/rcvd bytes 0/0, owners (0,255) Traffic received
at interface outside Locally received: 7544 (93 byte/s) Traffic received at interface NP
Identity Ifc Locally received: 0 (0 byte/s) UDP outside: 10.1.227.1/500 NP Identity Ifc:
10.1.226.1/500, flags -c, idle 1m22s, uptime 1m22s, timeout 2m0s, bytes 1580, cluster
sent/rcvd bytes 0/0, cluster sent/rcvd total bytes 0/0, owners (0,255) Traffic received at
interface outside Locally received: 864 (10 byte/s) Traffic received at interface NP Identity
Ifc Locally received: 716 (8 byte/s)
To troubleshoot the connection flow, first
see connections on all nodes by entering the cluster exec show conn
command on any node. Look for flows that have the following
flags: director (Y), backup (y), and forwarder (z). The
following example shows an SSH connection from
172.18.124.187:22 to 192.168.103.131:44727 on all three
ASAs; ASA 1 has the z flag showing it is a forwarder for the
connection, ASA3 has the Y flag showing it is the director
for the connection, and ASA2 has no special flags showing it
is the owner. In the outbound direction, the packets for
this connection enter the inside interface on ASA2 and exit
the outside interface. In the inbound direction, the packets
for this connection enter the outside interface on ASA 1 and
ASA3, are forwarded over the cluster control link to ASA2,
and then exit the inside interface on ASA2.
ciscoasa/ASA1/control node# cluster exec show conn
ASA1(LOCAL):**********************************************************
18 in use, 22 most used
Cluster stub connections: 0 in use, 5 most used
TCP outside 172.18.124.187:22 inside 192.168.103.131:44727, idle 0:00:00, bytes 37240828, flags z
ASA2:*****************************************************************
12 in use, 13 most used
Cluster stub connections: 0 in use, 46 most used
TCP outside 172.18.124.187:22 inside 192.168.103.131:44727, idle 0:00:00, bytes 37240828, flags UIO
ASA3:*****************************************************************
10 in use, 12 most used
Cluster stub connections: 2 in use, 29 most used
TCP outside 172.18.124.187:22 inside 192.168.103.131:44727, idle 0:00:03, bytes 0, flags Y
show cluster
info [conn-distribution |
packet-distribution | loadbalance |
flow-mobility counters]
The show cluster
info conn-distribution and show cluster info
packet-distribution commands show traffic
distribution across all cluster nodes. These commands can
help you to evaluate and adjust the external load balancer.
The show cluster
info loadbalance command shows connection
rebalance statistics.
The show cluster info flow-mobility
counters command shows EID movement and flow
owner movement information. See the following output for
show cluster info flow-mobility counters:
ciscoasa# show cluster info flow-mobility counters
EID movement notification received : 4
EID movement notification processed : 4
Flow owner moving requested : 2
show cluster info load-monitor
[details]
The show cluster info load-monitor
command shows the traffic load for cluster members for the
last interval and also the average over total number of
intervals configured (30 by default). Use the
details keyword to view
the value for each measure at each interval.
ciscoasa(cfg-cluster)# show cluster info load-monitor
ID Unit Name
0 B
1 A_1
Information from all units with 20 second interval:
Unit Connections Buffer Drops Memory Used CPU Used
Average from last 1 interval:
0 0 0 14 25
1 0 0 16 20
Average from last 30 interval:
0 0 0 12 28
1 0 0 13 27
ciscoasa(cfg-cluster)# show cluster info load-monitor details
ID Unit Name
0 B
1 A_1
Information from all units with 20 second interval
Connection count captured over 30 intervals:
Unit ID 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
Unit ID 1
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
Buffer drops captured over 30 intervals:
Unit ID 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
Unit ID 1
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
Memory usage(%) captured over 30 intervals:
Unit ID 0
25 25 30 30 30 35
25 25 35 30 30 30
25 25 30 25 25 35
30 30 30 25 25 25
25 20 30 30 30 30
Unit ID 1
30 25 35 25 30 30
25 25 35 25 30 35
30 30 35 30 30 30
25 20 30 25 25 30
20 30 35 30 30 35
CPU usage(%) captured over 30 intervals:
Unit ID 0
25 25 30 30 30 35
25 25 35 30 30 30
25 25 30 25 25 35
30 30 30 25 25 25
25 20 30 30 30 30
Unit ID 1
30 25 35 25 30 30
25 25 35 25 30 35
30 30 35 30 30 30
25 20 30 25 25 30
20 30 35 30 30 35
To display the aggregated count of in-use
connections for all nodes, enter:
ciscoasa# show cluster conn count
Usage Summary In Cluster:*********************************************
200 in use (cluster-wide aggregated)
cl2(LOCAL):***********************************************************
100 in use, 100 most used
cl1:******************************************************************
100 in use, 100 most used
show asp cluster
counter
This command is useful for datapath
troubleshooting.
Monitoring Cluster Routing
See the following
commands for cluster
routing:
show route cluster
debug route cluster
Shows cluster information for routing.
show lisp eid
Shows the ASA
EID table showing EIDs and site IDs.
See the
following output from the
cluster exec show lisp eid command.
ciscoasa# cluster exec show lisp eid
L1(LOCAL):************************************************************
LISP EID Site ID
33.44.33.105 2
33.44.33.201 2
11.22.11.1 4
11.22.11.2 4
L2:*******************************************************************
LISP EID Site ID
33.44.33.105 2
33.44.33.201 2
11.22.11.1 4
11.22.11.2 4
show asp table classify
domain inspect-lisp
This command is
useful for troubleshooting.
Configuring Logging for Clustering
See the following
command for configuring
logging for clustering:
logging device-id
Each node in the cluster generates syslog messages independently. You
can use the logging device-id
command to generate syslog messages with identical or different
device IDs to make messages appear to come from the same or different nodes in
the cluster.
Monitoring Cluster Interfaces
See the following commands for monitoring cluster interfaces:
show cluster interface-mode
Shows the cluster interface mode.
Debugging Clustering
See the following commands for debugging clustering:
debug cluster [ccp | datapath
| fsm | general | hc | license | rpc | transport]
Shows debug messages for clustering.
debug cluster flow-mobility
Shows events related to clustering flow mobility.
debug lisp eid-notify-intercept
Shows events when the eid-notify message is intercepted.
show cluster info trace
The show cluster info trace
command shows the debug information for further troubleshooting.
See the following output for the show cluster info trace command:
ciscoasa# show cluster info trace
Feb 02 14:19:47.456 [DBUG]Receive CCP message: CCP_MSG_LOAD_BALANCE
Feb 02 14:19:47.456 [DBUG]Receive CCP message: CCP_MSG_LOAD_BALANCE
Feb 02 14:19:47.456 [DBUG]Send CCP message to all: CCP_MSG_KEEPALIVE from 80-1 at CONTROL_NODE
For example, if you see the following messages showing that two nodes with the same
local-unit name are acting as the control node, it could mean
that either two nodes have the same local-unit name (check your
configuration), or a node is receiving its own broadcast messages (check
your network).
ciscoasa# show cluster info trace
May 23 07:27:23.113 [CRIT]Received datapath event 'multi control_nodes' with parameter 1.
May 23 07:27:23.113 [CRIT]Found both unit-9-1 and unit-9-1 as control_node units. Control_node role retained by unit-9-1, unit-9-1 will leave then join as a Data_node
May 23 07:27:23.113 [DBUG]Send event (DISABLE, RESTART | INTERNAL-EVENT, 5000 msecs, Detected another Control_node, leave and re-join as Data_node) to FSM. Current state CONTROL_NODE
May 23 07:27:23.113 [INFO]State machine changed from state CONTROL_NODE to DISABLED
Examples for ASA
Virtual Clustering
These examples include all cluster-related ASA configuration
for typical deployments.
Individual Interface Routed Mode North-South Inter-Site Example
The following example shows 2 ASA cluster nodes at each of 2 data
centers placed between inside and outside routers (North-South insertion). The cluster
nodes are connected by the cluster control link over the DCI. The inside and outside
routers at each data center use OSPF and PBR or ECMP to load balance the traffic between
cluster members. By assigning a higher cost route across the DCI, traffic stays within
each data center unless all ASA cluster nodes at a given site go down. In the event of a
failure of all cluster nodes at one site, traffic goes from each router over the DCI to
the ASA cluster nodes at the other site.
Reference for Clustering
This section includes more information about how clustering operates.
ASA Features and Clustering
Some ASA features are not supported with ASA clustering, and some are
only supported on the control node. 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.
Unified Communication features that rely on TLS Proxy
Remote access VPN (SSL VPN and IPsec VPN)
Virtual Tunnel Interfaces (VTIs)
The following application inspections:
CTIQBE
H323, H225, and RAS
IPsec passthrough
MGCP
MMP
RTSP
SCCP (Skinny)
WAAS
WCCP
Botnet Traffic Filter
Auto Update Server
DHCP client, server, and proxy. DHCP relay is
supported.
VPN load balancing
Failover
Integrated Routing and Bridging
FIPS mode
Centralized Features for Clustering
The following features are only supported on the control node, and are
not scaled for the cluster.
Note
Traffic for centralized features is forwarded from member
nodes to the control node over the cluster control link.
If you use the rebalancing feature, traffic for centralized
features may be rebalanced to non-control nodes before the traffic is classified
as a centralized feature; if this occurs, the traffic is then sent back to the
control node.
For centralized features, if the control node fails, all
connections are dropped, and you have to re-establish the connections on the new
control node.
The following application inspections:
DCERPC
ESMTP
IM
NetBIOS
PPTP
RADIUS
RSH
SNMP
SQLNET
SUNRPC
TFTP
XDMCP
Static route monitoring
Authentication and Authorization for network access.
Accounting is decentralized.
Filtering Services
Site-to-site VPN
Multicast routing
Features Applied to Individual Nodes
These features are applied to each ASA node, instead of the cluster as a whole or to the
control node.
QoS—The QoS policy is synced across the cluster as part of configuration replication.
However, the policy is enforced on each node independently. For example,
if you configure policing on output, then the conform rate and conform
burst values are enforced on traffic exiting a particular ASA. In a
cluster with 3 nodes and with traffic evenly distributed, the conform
rate actually becomes 3 times the rate for the cluster.
Threat detection—Threat detection works on each node independently; for example, the top
statistics is node-specific. Port scanning detection, for example, does
not work because scanning traffic will be load-balanced between all
nodes, and one node will not see all traffic.
Resource management—Resource management in multiple context mode is enforced separately on
each node based on local usage.
LISP traffic—LISP traffic on UDP port 4342 is inspected by each receiving node, but is not
assigned a director. Each node adds to the EID table that is shared
across the cluster, but the LISP traffic itself does not participate in
cluster state sharing.
AAA for Network Access and Clustering
AAA for network access consists of three components: authentication,
authorization, and accounting. Authentication and authorization are implemented
as centralized features on the clustering control node with replication of the
data structures to the cluster data nodes. If a control node is elected, the new
control node will have all the information it needs to continue uninterrupted
operation of the established authenticated users and their associated
authorizations. Idle and absolute timeouts for user authentications are
preserved when a control node change occurs.
Accounting is implemented as a distributed feature in a cluster.
Accounting is done on a per-flow basis, so the cluster node owning a flow will
send accounting start and stop messages to the AAA server when accounting is
configured for a flow.
Connection Settings and Clustering
Connection limits are enforced cluster-wide (see the set connection conn-max, set
connection embryonic-conn-max, set
connection per-client-embryonic-max, and
set connection per-client-max
commands). Each node has an
estimate of the cluster-wide counter values based on broadcast messages. Due to
efficiency considerations, the configured connection limit across the cluster
might not be enforced exactly at the limit number. Each node may overestimate or
underestimate the cluster-wide counter value at any given time. However, the
information will get updated over time in a load-balanced cluster.
Dynamic Routing and Clustering
In Individual interface mode, each node runs the routing protocol as a
standalone router, and routes are learned by each node independently.
Figure 1. Dynamic Routing in Individual Interface Mode
In the above diagram, Router A learns that there are 4 equal-cost paths
to Router B, each through a node. ECMP is used to load balance traffic between
the 4 paths. Each node picks a different router ID when talking to external
routers.
You must configure a cluster pool for the router ID so that each node has
a separate router ID.
EIGRP does not
form neighbor relationships with cluster peers in individual interface mode.
Note
If the cluster has multiple adjacencies to the same router for redundancy purposes,
asymmetric routing can lead to unacceptable traffic loss. To avoid
asymmetric routing, group all of these node interfaces into the same traffic
zone.
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.
If you use AAA for FTP access, then the control channel flow is
centralized on the control node.
ICMP Inspection and Clustering
The flow of ICMP and ICMP error packets through the cluster varies depending on
whether ICMP/ICMP error inspection is enabled. Without ICMP inspection, ICMP is
a one-direction flow, and there is no director flow support. With ICMP
inspection, the ICMP flow becomes two-directional and is backed up by a
director/backup flow. One difference for an inspected ICMP flow is in the
director handling of a forwarded packet: the director will forward the ICMP echo
reply packet to the flow owner instead of returning the packet to the forwarder.
Multicast Routing and Clustering
In Individual interface mode, units do not act independently with
multicast. All data and routing packets are processed and forwarded by the control unit,
thus avoiding packet replication.
NAT and Clustering
NAT can affect the overall throughput of the cluster. Inbound and
outbound NAT packets can be sent to different ASAs 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 ASA that is not the NAT owner, it is forwarded over the cluster control link to
the owner, causing large amounts of traffic on the cluster control link. Note
that the receiving node does not create a forwarding flow to the owner, because
the NAT owner may not end up creating a connection for the packet depending on
the results of security and policy checks.
If you still want to use NAT in clustering, then consider the
following guidelines:
No Proxy ARP—For Individual interfaces, a proxy ARP
reply is never sent for mapped addresses. This prevents the adjacent
router from maintaining a peer relationship with an ASA that may no
longer be in the cluster. The upstream router needs a static route or
PBR with Object Tracking for the mapped addresses that points to the
Main cluster IP address. This is not an issue for a Spanned
EtherChannel, because there is only one IP address associated with the
cluster interface.
No interface PAT on an Individual
interface—Interface PAT is not supported for Individual interfaces.
PAT with Port Block Allocation—See the following guidelines for this
feature:
Maximum-per-host limit is not a cluster-wide limit, and is enforced on each node
individually. Thus, in a 3-node cluster with the
maximum-per-host limit configured as 1, if the traffic from a
host is load-balanced across all 3 nodes, then it can get
allocated 3 blocks with 1 in each node.
Port blocks created on the backup node from the backup pools are not accounted for when
enforcing the maximum-per-host limit.
On-the-fly PAT rule modifications, where the PAT pool is modified with a completely new
range of IP addresses, will result in xlate backup creation
failures for the xlate backup requests that were still in
transit while the new pool became effective. This behavior is
not specific to the port block allocation feature, and is a
transient PAT pool issue seen only in cluster deployments where
the pool is distributed and traffic is load-balanced across the
cluster nodes.
When operating in a cluster, you cannot simply change the block allocation size. The new
size is effective only after you reload each device in the
cluster. To avoid having to reload each device, we recommend
that you delete all block allocation rules and clear all xlates
related to those rules. You can then change the block size and
recreate the block allocation rules.
NAT pool address distribution for dynamic PAT—When you configure a PAT pool, the cluster
divides each IP address in the pool into port blocks. By default, each
block is 512 ports, but if you configure port block allocation rules,
your block setting is used instead. These blocks are distributed evenly
among the nodes in the cluster, so that each node has one or more blocks
for each IP address in the PAT pool. Thus, you could have as few as one
IP address in a PAT pool for a cluster, if that is sufficient for the
number of PAT’ed connections you expect. Port blocks cover the
1024-65535 port range, unless you configure the option to include the
reserved ports, 1-1023, on the PAT pool NAT rule.
Reusing a PAT pool in multiple rules—To use the same PAT pool in multiple
rules, you must be careful about the interface selection in the rules.
You must either use specific interfaces in all rules, or "any" in all
rules. You cannot mix specific interfaces and "any" across the rules, or
the system might not be able to match return traffic to the right node
in the cluster. Using unique PAT pools per rule is the most reliable
option.
No round-robin—Round-robin for a PAT pool is not supported with
clustering.
No extended PAT—Extended PAT is not supported with clustering.
Dynamic NAT xlates managed by the control node—The control node
maintains and replicates the xlate table to data nodes. When a data node
receives a connection that requires dynamic NAT, and the xlate is not in
the table, it requests the xlate from the control node. The data node
owns the connection.
Stale xlates—The xlate idle time on the connection owner does not get
updated. Thus, the idle time might exceed the idle timeout. An idle
timer value higher than the configured timeout with a refcnt of 0 is an
indication of a stale xlate.
Per-session PAT feature—Although not exclusive to clustering, the
per-session PAT feature improves the scalability of PAT and, for
clustering, allows each data node to own PAT connections; by contrast,
multi-session PAT connections have to be forwarded to and owned by the
control node. By default, all TCP traffic and UDP DNS traffic use a
per-session PAT xlate, whereas ICMP and all other UDP traffic uses
multi-session. You can configure per-session NAT rules to change these
defaults for TCP and UDP, but you cannot configure per-session PAT for
ICMP. For example, with an increasing use of Quic protocol over UDP/443
as a best performance alternative compared to HTTPS TLS over TCP/443,
you should enable per-session PAT for UDP/443. For traffic that benefits
from multi-session PAT, such as H.323, SIP, or Skinny, you can disable
per-session PAT for the associated TCP ports (the UDP ports for those
H.323 and SIP are already multi-session by default). For more
information about per-session PAT, see the firewall configuration guide.
No static PAT for the following inspections—
FTP
PPTP
RSH
SQLNET
TFTP
XDMCP
SIP
If you have an extremely large number of NAT rules, over ten thousand, you should enable
the transactional commit model using the asp rule-engine
transactional-commit nat command in the device
CLI. Otherwise, the node might not be able to join the cluster.
SCTP and Clustering
An SCTP association can be created on any node (due to load balancing); its multi-homing
connections must reside on the same node.
SIP Inspection and Clustering
A control flow can be created on any node (due to load balancing); its
child data flows must reside on the same node.
TLS Proxy configuration is
not supported.
SNMP and Clustering
An
SNMP agent polls each individual ASA by its 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 control node is elected, the poll to the new control node will fail.
When using SNMPv3 with clustering, if you add a new
cluster node after the initial cluster formation, then SNMPv3 users are not
replicated to the new node.You must re-add them on the
control node to force the users to replicate to the new node, or directly on
the data node.
STUN and Clustering
STUN inspection is supported in failover and cluster modes, as pinholes are replicated.
However, the transaction ID is not replicated among nodes. In the case where a
node fails after receiving a STUN Request and another node received the STUN
Response, the STUN Response will be dropped.
Syslog and NetFlow and Clustering
Syslog—Each node in the cluster generates
its own syslog messages. You can configure logging so that each node
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 nodes in the cluster. If you configure logging to use the
hostname as the device ID, syslog messages generated by all nodes look
as if they come from a single node. If you configure logging to use the
local-node name that is assigned in the cluster bootstrap configuration
as the device ID, syslog messages look as if they come from different
nodes.
NetFlow—Each node in the cluster generates its own NetFlow stream. The
NetFlow collector can only treat each ASA as a separate NetFlow
exporter.
Cisco TrustSec and Clustering
Only the control node learns security group tag (SGT) information. The
control node then populates the SGT to data nodes, and data nodes can make a
match decision for SGT based on the security policy.
VPN and Clustering
Site-to-site VPN is a centralized feature; only the control
node supports VPN connections.
Note
Remote access VPN is not supported with clustering.
VPN functionality is limited to the control node and does not
take advantage of the cluster high availability capabilities. If the control node
fails, all existing VPN connections are lost, and VPN users will see a disruption in
service. When a new control node is elected, you must reestablish the VPN
connections.
For connections to an Individual interface when using PBR or
ECMP, you must always connect to the Main cluster IP address, not a Local address.
VPN-related keys and certificates are replicated to all nodes.
Performance Scaling Factor
When you combine multiple units into a cluster, you can expect the total cluster
performance to be approximately 80% of the maximum combined throughput.
For example, if your model can handle approximately 10 Gbps of traffic when running
alone, then for a cluster of 8 units, the maximum combined throughput will be
approximately 80% of 80 Gbps (8 units x 10 Gbps): 64 Gbps.
Control Node Election
Nodes of the cluster communicate over the cluster control link to
elect a control node as follows:
When you enable clustering for a node (or when it first
starts up with clustering already enabled), it broadcasts an election request
every 3 seconds.
Any other nodes with a higher priority respond to the
election request; the priority is set between 1 and 100, where 1 is the highest
priority.
If after 45 seconds, a node does not receive a response
from another node with a higher priority, then it becomes the control node.
Note
If multiple nodes tie for the highest priority, the
cluster node name and then the serial number is used to determine the
control node.
If a node later joins the cluster with a higher priority,
it does not automatically become the control node; the existing control node
always remains as the control node unless it stops responding, at which point a
new control node is elected.
In a "split brain" scenario when there are temporarily multiple control nodes,
then the node with highest priority retains the role while the other nodes
return to data node roles.
Note
You can manually force a node to become the control node. For
centralized features, if you force a control node change, then all connections are
dropped, and you have to re-establish the connections on the new control node.
High Availability Within the ASA
Virtual Cluster
The ASA
virtual Clustering provides high availability by monitoring node and interface health and by replicating connection states between
nodes.
Node Health Monitoring
Each node periodically sends a broadcast heartbeat packet over the cluster control link. If the control node
does not receive any heartbeat packets
or other packets from a data node within the configurable timeout period, then the
control node removes the data node from the cluster. If the data nodes do not
receive packets from the control node, then a new control node is elected from
the remaining nodes.
If nodes cannot reach each other over the cluster control link because of a
network failure and not because a node has actually failed, then the cluster may
go into a "split brain" scenario where isolated data nodes will elect their own
control nodes. For example, if a router fails between two cluster locations,
then the original control node at location 1 will remove the location 2 data
nodes from the cluster. Meanwhile, the nodes at location 2 will elect their own
control node and form their own cluster. Note that asymmetric traffic may fail
in this scenario. After the cluster control link is restored, then the control
node that has the higher priority will keep the control node’s role.
Each node monitors the link status of all named hardware
interfaces in use, and reports status changes to the control node.
When you enable health monitoring, all physical interfaces are
monitored by default; you can optionally disable monitoring per interface. Only
named interfaces can be monitored.
A node is removed from the cluster if its monitored interfaces
fail. The amount of time before the ASA removes a member from the cluster depends on
whether the node is an established member or is joining the cluster. The ASA does
not monitor interfaces for the first 90 seconds that a node joins the cluster.
Interface status changes during this time will not cause the ASA to be removed from
the cluster. The node is removed after 500 ms, regardless of the node state.
Status After Failure
When a node in the cluster fails, the connections hosted by that node are
seamlessly transferred to other nodes; state information for traffic flows is
shared over the control node's cluster control link.
If the control node fails, then another member of the cluster with the
highest priority (lowest number) becomes the control node.
The ASA automatically tries to rejoin the cluster, depending on the failure event.
Note
When the ASA becomes inactive and fails to automatically rejoin the cluster, all data
interfaces are shut down; only the management-only interface
can send and receive traffic. The
management interface remains up using the IP address the node received
from the cluster IP pool. However if you reload, and the node is still
inactive in the cluster, the management interface is disabled. You must
use the console port for any further configuration.
Rejoining the Cluster
After a cluster node is removed from the cluster, how it can
rejoin the cluster depends on why it was removed:
Failed cluster control link when initially
joining—After you resolve the problem with the cluster control link, you
must manually rejoin the cluster by re-enabling clustering
at the CLI by entering cluster group name, and then enable.
Failed cluster control link after joining the cluster—The ASA automatically
tries to rejoin every 5 minutes, indefinitely. This behavior is
configurable.
Failed data interface—The ASA 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 ASA disables clustering.
After you resolve the problem with the data interface, you have to manually
enable clustering at the CLI by entering
cluster group name, and then enable. This behavior is configurable.
Failed node—If the node was removed from the cluster
because of a node health check failure, then rejoining the cluster depends
on the source of the failure. For example, a temporary power failure means
the node will rejoin the cluster when it starts up again as long as the
cluster control link is up and clustering is still enabled
with the enable command. The ASA
attempts to rejoin the cluster every 5 seconds.
Internal error—Internal failures include: application sync timeout;
inconsistent application statuses; and so on. A node will attempt to rejoin
the cluster automatically at the following intervals: 5 minutes, 10 minutes,
and then 20 minutes. This behavior is configurable.
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. The backup
owner is usually also the director.
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.
Table 1. 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
Includes AAA rules (uauth).
IPv6 Neighbor database
Yes
—
Dynamic routing
Yes
—
SNMP Engine ID
No
—
Distributed VPN (Site-to-Site) for Firepower 4100/9300
Yes
Backup
session becomes the active session, then a new backup session is created.
How the ASA
Virtual Cluster Manages Connections
Connections can be load-balanced to multiple nodes of the cluster.
Connection roles determine how connections are handled in both normal operation
and in a high availability situation.
Connection Roles
See the following roles defined for each connection:
Owner—Usually, the node 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 nodes receive
packets from the connection, the director chooses a new owner from those
nodes.
Backup owner—The node that stores TCP/UDP state information received from the owner, so that
the connection can be seamlessly transferred to a new owner in case of a
failure. The backup owner does not take over the connection in the event
of a failure. If the owner becomes unavailable, then the first node 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.
As long as the director (see below) is not the same node as the owner, then the director is
also the backup owner. If the owner chooses itself as the director, then
a separate backup owner is chosen.
For clustering on the Firepower 9300, which can include up to 3 cluster nodes in one chassis, if the backup owner is on the
same chassis as the owner, then an additional backup owner will be chosen from another chassis to protect flows from a chassis
failure.
If you enable director localization for inter-site clustering, then
there are two backup owner roles: the local backup and the global
backup. The owner always chooses a local backup at the same site as
itself (based on site ID). The global backup can be at any site, and
might even be the same node as the local backup. The owner sends
connection state information to both backups.
If you enable site redundancy, and the backup owner is at the
same site as the owner, then an additional backup owner will be chosen from
another site to protect flows from a site failure. Chassis backup and site
backup are independent, so in some cases a flow will have both a chassis backup
and a site backup.
Director—The node that handles owner lookup requests from forwarders.
When the owner receives a new connection, it chooses a director based on
a hash of the source/destination IP address and ports (see below for
ICMP hash details), and sends a message to the director to register the
new connection. If packets arrive at any node other than the owner, the
node queries the director about which node 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.
As long as the director is not the same node as the owner, then the director is also the
backup owner (see above). If the owner chooses itself as the director,
then a separate backup owner is chosen.
If you enable director localization for inter-site clustering, then
there are two director roles: the local director and the global
director. The owner always chooses a local director at the same site as
itself (based on site ID). The global director can be at any site, and
might even be the same node as the local director. If the original owner
fails, then the local director chooses a new connection owner at the
same site.
ICMP/ICMPv6 hash details:
For Echo packets, the source port is the ICMP identifier, and the
destination port is 0.
For Reply packets, the source port is 0, and the destination port
is the ICMP identifier.
For other packets, both source and destination ports are 0.
Forwarder—A node 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. If you enable director
localization, then the forwarder always queries the local director.
The forwarder only queries the global director if the local director
does not know the owner, for example, if a cluster member receives
packets for a connection that is owned on a different site.
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.
Note
We do not recommend disabling TCP sequence randomization when using
clustering. There is a small chance that some TCP sessions won't be
established, because the SYN/ACK packet might be dropped.
Fragment Owner—For fragmented packets, cluster nodes that receive a fragment determine a
fragment owner using a hash of the fragment source IP address,
destination IP address, and the packet ID. All fragments are then
forwarded to the fragment owner over the cluster control link. Fragments
may be load-balanced to different cluster nodes, because only the first
fragment includes the 5-tuple used in the switch load balance hash.
Other fragments do not contain the source and destination ports and may
be load-balanced to other cluster nodes. The fragment owner temporarily
reassembles the packet so it can determine the director based on a hash
of the source/destination IP address and ports. If it is a new
connection, the fragment owner will register to be the connection owner.
If it is an existing connection, the fragment owner forwards all
fragments to the provided connection owner over the cluster control
link. The connection owner will then reassemble all fragments.
When a connection uses Port Address Translation (PAT), then the
PAT type (per-session or multi-session) influences which member of the cluster
becomes the owner of a new connection:
Per-session PAT—The owner is the node that receives the initial packet in the connection.
By default,
TCP and DNS UDP traffic use per-session PAT.
Multi-session PAT—The owner is always the control node. If a multi-session PAT connection is
initially received by a data node, then the data node forwards the
connection to the control node.
By default, UDP (except for DNS UDP) and ICMP traffic use multi-session PAT, so these
connections are always owned by the control node.
You can change the per-session PAT defaults for TCP and UDP so
connections for these protocols are handled per-session or multi-session
depending on the configuration. For ICMP, you cannot change from the default
multi-session PAT. For more information about per-session PAT, see the firewall
configuration guide.
New Connection Ownership
When a new connection is directed to a node of the cluster via load
balancing, that node owns both directions of the connection. If any
connection packets arrive at a different node, they are forwarded to the
owner node over the cluster control link. For best
performance, proper external load balancing is required for both
directions of a flow to arrive at the same node, and for flows to be
distributed evenly between nodes. If a reverse flow arrives at
a different node, it is redirected back to the original node.
Sample Data Flow for TCP
The following example shows the establishment of a new
connection.
The SYN packet originates from the client and is delivered to one ASA (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.
The SYN-ACK packet originates from the server and is delivered to a
different ASA (based on the load balancing method). This ASA is the forwarder.
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.
The owner sends a state update to the director, and forwards the
SYN-ACK to the client.
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.
Any subsequent packets delivered to the forwarder will be
forwarded to the owner.
If packets are delivered to any additional nodes, it will query the
director for the owner and establish a flow.
Any state change for the flow results in a state update from the
owner to the director.
Sample Data Flow for ICMP and UDP
The following example shows the establishment of a new connection.
Figure 2. ICMP and UDP Data Flow
The first UDP packet originates from the client and is delivered
to one ASA (based on the load balancing method).
The node that received the first packet queries the director node that is chosen based on a
hash of the source/destination IP address and ports.
The director finds no existing flow, creates a director flow and forwards the packet back
to the previous node. In other words, the director has elected an owner
for this flow.
The owner creates the flow, sends a state update to the director, and
forwards the packet to the server.
The second UDP packet originates from the server and is delivered to the
forwarder.
The forwarder queries the director for ownership information. For
short-lived flows such as DNS, instead of querying, the forwarder
immediately sends the packet to the director, which then sends it to the
owner.
The director replies to the forwarder with ownership information.
The forwarder creates a forwarding flow to record owner information and
forwards the packet to the owner.
The owner forwards the packet to the client.
Rebalancing New TCP Connections Across the Cluster
If the load balancing capabilities of the upstream or downstream
routers result in unbalanced flow distribution, you can configure new
connection rebalancing so nodes with higher new connections per second will
redirect new TCP flows to other nodes. No existing flows will be moved to
other nodes.
Because this command only rebalances based on connections
per second, the total number of established connections on each node is not
considered, and the total number of connections may not be equal.
Once a connection is offloaded to a different node, it becomes an asymmetric
connection.
Do not configure connection
rebalancing for inter-site topologies; you do not want new connections
rebalanced to cluster members at a different site.
History for ASA
Virtual Clustering
Feature Name
Version
Feature Information
Removal of biased language
9.19(1)
Commands, command output, and syslog messages that contained the
terms "Master" and "Slave" have been changed to "Control" and
"Data."
New/Modified commands: cluster
control-node, enable
as-data-node,
prompt, show cluster
history, show cluster
info
ASAv30, ASAv50, and ASAv100 clustering for VMware and KVM
9.17(1)
The ASA
virtual clustering lets you group up to 16 ASA
virtuals together as a single logical device. 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. The ASA
virtual clustering supports Individual Interface mode in routed
firewall mode; Spanned EtherChannels are not supported. The ASA
virtual uses a VXLAN virtual interface (VNI) for the cluster control
link.
New/Modified commands:
cluster-interface vni, nve-only
cluster, peer-group, show cluster
info, show cluster info instance-type,
show nve 1
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