1-5
Cisco ASA Series CLI Configuration Guide
Chapter 1 Routing Overview
Supported Internet Protocols for Routing
The same problem may happen when there are no route flaps on the ASA itself, but some routing process
is flapping around it, sending source-translated packets that belong to the same flow through the ASA
using different interfaces. Destination-translated return packets may be forwarded back using the wrong
egress interface.
This issue has a high probability in some security traffic configurations, where virtually any traffic may
be either source-translated or destination-translated, depending on the direction of the initial packet in
the flow. When this issue occurs after a route flap, it can be resolved manually by using the
clear xlate
command, or automatically resolved by an XLATE timeout. The XLATE timeout may be decreased if
necessary. To ensure that this issue rarely occurs, make sure that there are no route flaps on the ASA and
around it. That is, ensure that destination-translated packets that belong to the same flow are always
forwarded the same way through the ASA.
Supported Internet Protocols for Routing
The ASA supports several Internet protocols for routing. Each protocol is briefly described in this
section.
•
Enhanced Interior Gateway Routing Protocol (EIGRP)
EIGRP is a Cisco proprietary protocol that provides compatibility and seamless interoperation with
IGRP routers. An automatic-redistribution mechanism allows IGRP routes to be imported into
Enhanced IGRP, and vice versa, so it is possible to add Enhanced IGRP gradually into an existing
IGRP network.
For more information about configuring EIGRP, see the
“Configuring EIGRP” section on page 1-3
•
Open Shortest Path First (OSPF)
OSPF is a routing protocol developed for Internet Protocol (IP) networks by the interior gateway
protocol (IGP) working group of the Internet Engineering Task Force (IETF). OSPF uses a link-state
algorithm to build and calculate the shortest path to all known destinations. Each router in an OSPF
area includes an identical link-state database, which is a list of each of the router usable interfaces
and reachable neighbors.
For more information about configuring OSPF, see the
“Configuring OSPFv2” section on page 1-5
•
Routing Information Protocol (RIP)
RIP is a distance-vector protocol that uses hop count as its metric. RIP is widely used for routing
traffic in the global Internet and is an interior gateway protocol (IGP), which means that it performs
routing within a single autonomous system.
For more information about configuring RIP, see the
“Configuring RIP” section on page 1-4
Information About the Routing Table
This section includes the following topics:
•
Displaying the Routing Table, page 1-6
•
How the Routing Table Is Populated, page 1-6
•
How Forwarding Decisions Are Made, page 1-8
•
Dynamic Routing and Failover, page 1-9
•
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: ......