Cisco DPC User Manual page 64

How Do I Configure My DOCSIS Residential Gateway?
Field
Phase 2 authentication Allows you to select an authentication type for another level of
Phase 2 SA lifetime
Configuring Firewall Protection
Use the Setup Firewall - Options page to configure webpage filtering and firewall
protection. This page allows you to enable various firewall protection filters.
Note: If you are not familiar with the advanced settings detailed in this section,
contact your service provider before you attempt to change any of the residential
gateway default firewall options settings.
Click Options in the Firewall section of the Setup page to access the Setup Firewall -
Options page.
64
Description
security. Select one of the following three authentication types:

MD5

SHA

Null (none)
You may choose any authentication type as long as the other end of the
VPN tunnel uses the same method
Note: SHA is recommended because it is more secure.
Allows you to enter the number of seconds for an individual rotating
key to last until a re-key negotiation between each endpoint occurs.
Smaller lifetimes are generally more secure since it would give a
hacker a smaller amount of time to try to crack the key. However, key
negotiation does take up bandwidth, so network throughput is
sacrificed with small lifetimes. The default setting for Phase 2 is 3,600
seconds.
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