Cisco Cisco IOS Software Release 12.4(23)
Appendix A—IPSec Operation
IPSec Operation
53
Security Target For Cisco IOS IPSec
devices will have agreed on an encryption algorithm (for example, 3DES) and an authentication
algorithm (for example, SHA), and have a shared session key. Now, Bob’s internetworking device can
encrypt Bob’s IP packet, place it into a new IPSec packet and send it to Alice’s internetworking device.
When Alice’s internetworking device receives the IPSec packet, it looks up the IPSec SA, properly
processes and unpacks the original datagram, and forwards it over to Alice. Note that this process is
transparent to both Alice and Bob.
algorithm (for example, SHA), and have a shared session key. Now, Bob’s internetworking device can
encrypt Bob’s IP packet, place it into a new IPSec packet and send it to Alice’s internetworking device.
When Alice’s internetworking device receives the IPSec packet, it looks up the IPSec SA, properly
processes and unpacks the original datagram, and forwards it over to Alice. Note that this process is
transparent to both Alice and Bob.
Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and
figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and
coincidental.
figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and
coincidental.
© 2007 Cisco Systems, Inc. All rights reserved.
CCVP, the Cisco logo, and Welcome to the Human Network are trademarks of Cisco Systems, Inc.; Changing the Way We Work, Live, Play, and Learn is
a service mark of Cisco Systems, Inc.; and Access Registrar, Aironet, Catalyst, CCDA, CCDP, CCIE, CCIP, CCNA, CCNP, CCSP, Cisco, the Cisco
Certified Internetwork Expert logo, Cisco IOS, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Cisco Unity,
Enterprise/Solver, EtherChannel, EtherFast, EtherSwitch, Fast Step, Follow Me Browsing, FormShare, GigaDrive, HomeLink, Internet Quotient, IOS,
iPhone, IP/TV, iQ Expertise, the iQ logo, iQ Net Readiness Scorecard, iQuick Study, LightStream, Linksys, MeetingPlace, MGX, Networkers,
Networking Academy, Network Registrar, PIX, ProConnect, ScriptShare, SMARTnet, StackWise, The Fastest Way to Increase Your Internet Quotient,
and TransPath are registered trademarks of Cisco Systems, Inc. and/or its affiliates in the United States and certain other countries.
a service mark of Cisco Systems, Inc.; and Access Registrar, Aironet, Catalyst, CCDA, CCDP, CCIE, CCIP, CCNA, CCNP, CCSP, Cisco, the Cisco
Certified Internetwork Expert logo, Cisco IOS, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Cisco Unity,
Enterprise/Solver, EtherChannel, EtherFast, EtherSwitch, Fast Step, Follow Me Browsing, FormShare, GigaDrive, HomeLink, Internet Quotient, IOS,
iPhone, IP/TV, iQ Expertise, the iQ logo, iQ Net Readiness Scorecard, iQuick Study, LightStream, Linksys, MeetingPlace, MGX, Networkers,
Networking Academy, Network Registrar, PIX, ProConnect, ScriptShare, SMARTnet, StackWise, The Fastest Way to Increase Your Internet Quotient,
and TransPath are registered trademarks of Cisco Systems, Inc. and/or its affiliates in the United States and certain other countries.
All other trademarks mentioned in this document or Website are the property of their respective owners. The use of the word partner does not imply a
partnership relationship between Cisco and any other company. (0711R)
partnership relationship between Cisco and any other company. (0711R)