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Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring a Cluster of ASAs
Information About ASA Clustering
Load Balancing
The EtherChannel link is selected using a proprietary hash algorithm, based on source or destination IP
addresses and TCP and UDP port numbers.
Note
On the ASA, do not change the load-balancing algorithm from the default (see the
EtherChannel” section on page 1-30
). On the switch, we recommend that you use one of the following
algorithms:
source-dest-ip
or
source-dest-ip-port
(see the Nexus OS or IOS
port-channel
load-balance
command). Do not use a
vlan
keyword in the load-balance algorithm because it can cause
unevenly distributed traffic to the ASAs in a cluster.
The number of links in the EtherChannel affects load balancing. See the
for more information.
Symmetric load balancing is not always possible. If you configure NAT, then forward and return packets
will have different IP addresses and/or ports. Return traffic will be sent to a different unit based on the
hash, and the cluster will have to redirect most returning traffic to the correct unit. See the
for more information.
EtherChannel Redundancy
The EtherChannel has built-in redundancy. It monitors the line protocol status of all links. If one link
fails, traffic is re-balanced between remaining links. If all links in the EtherChannel fail on a particular
unit, but other units are still active, then the unit is removed from the cluster.
Connecting to a VSS or vPC
You can include multiple interfaces per ASA in the Spanned EtherChannel. Multiple interfaces per ASA
are especially useful for connecting to both switches in a VSS or vPC. Keep in mind that an
EtherChannel can have only 8 active interfaces out of 16 maximum; the remaining 8 interfaces are on
standby in case of link failure. The following figure shows a 4-ASA cluster and an 8-ASA cluster, both
with a total of 16 links in the EtherChannel. The active links are shown as solid lines, while the inactive
links are dotted. cLACP load-balancing can automatically choose the best 8 links to be active in the
EtherChannel. As shown, cLACP helps achieve load balancing at the link level.
Summary of Contents for 5505 - ASA Firewall Edition Bundle
Page 28: ...Glossary GL 24 Cisco ASA Series CLI Configuration Guide ...
Page 61: ...P A R T 1 Getting Started with the ASA ...
Page 62: ......
Page 219: ...P A R T 2 Configuring High Availability and Scalability ...
Page 220: ......
Page 403: ...P A R T 2 Configuring Interfaces ...
Page 404: ......
Page 499: ...P A R T 2 Configuring Basic Settings ...
Page 500: ......
Page 533: ...P A R T 2 Configuring Objects and Access Lists ...
Page 534: ......
Page 601: ...P A R T 2 Configuring IP Routing ...
Page 602: ......
Page 745: ...P A R T 2 Configuring Network Address Translation ...
Page 746: ......
Page 845: ...P A R T 2 Configuring AAA Servers and the Local Database ...
Page 846: ......
Page 981: ...P A R T 2 Configuring Access Control ...
Page 982: ......
Page 1061: ...P A R T 2 Configuring Service Policies Using the Modular Policy Framework ...
Page 1062: ......
Page 1093: ...P A R T 2 Configuring Application Inspection ...
Page 1094: ......
Page 1191: ...P A R T 2 Configuring Unified Communications ...
Page 1192: ......
Page 1333: ...P A R T 2 Configuring Connection Settings and QoS ...
Page 1334: ......
Page 1379: ...P A R T 2 Configuring Advanced Network Protection ...
Page 1380: ......
Page 1475: ...P A R T 2 Configuring Modules ...
Page 1476: ......
Page 1549: ...P A R T 2 Configuring VPN ...
Page 1550: ......
Page 1965: ...P A R T 2 Configuring Logging SNMP and Smart Call Home ...
Page 1966: ......
Page 2059: ...P A R T 2 System Administration ...
Page 2060: ......
Page 2098: ...1 8 Cisco ASA Series CLI Configuration Guide Chapter 1 Troubleshooting Viewing the Coredump ...
Page 2099: ...P A R T 2 Reference ...
Page 2100: ......