1-4
Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring Connection Settings
Licensing Requirements for Connection Settings
Inspection Overview” section on page 1-30
for more detailed information about the stateful firewall.
TCP packets that match existing connections in the fast path can pass through the ASA without
rechecking every aspect of the security policy. This feature maximizes performance. However, the
method of establishing the session in the fast path using the SYN packet, and the checks that occur in
the fast path (such as TCP sequence number), can stand in the way of asymmetrical routing solutions:
both the outbound and inbound flow of a connection must pass through the same ASA.
For example, a new connection goes to ASA 1. The SYN packet goes through the session management
path, and an entry for the connection is added to the fast path table. If subsequent packets of this
connection go through ASA 1, then the packets will match the entry in the fast path, and are passed
through. But if subsequent packets go to ASA 2, where there was not a SYN packet that went through
the session management path, then there is no entry in the fast path for the connection, and the packets
are dropped.
shows an asymmetric routing example where the outbound traffic goes through
a different ASA than the inbound traffic:
Figure 1-1
Asymmetric Routing
If you have asymmetric routing configured on upstream routers, and traffic alternates between two
ASAs, then you can configure TCP state bypass for specific traffic. TCP state bypass alters the way
sessions are established in the fast path and disables the fast path checks. This feature treats TCP traffic
much as it treats a UDP connection: when a non-SYN packet matching the specified networks enters the
ASA, and there is not an fast path entry, then the packet goes through the session management path to
establish the connection in the fast path. Once in the fast path, the traffic bypasses the fast path checks.
Licensing Requirements for Connection Settings
ISP A
Inside
network
Outbound?Traffic
Return?Traffic
ISP B
251155
Security
appliance 1
Security
appliance 2
Model
License Requirement
All models
Base License.
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: ......