3Com Switch 8800 Family IPsec Module Configuration and Command reference Guide

LNS Configuration 119
By default, AVP is transferred in plain text.
Setting Hello Interval in
Tunnel
In order to check the connectivity of the Tunnel between LAC and LNS, LAC and
LNS send Hello packets to each other periodically and the receiver will respond
upon the receipt of the packets. If LAC or LNS does not receive response from the
peer end in a specified interval, it will resend Hello packet and will regard the L2TP
Tunnel connection has been disconnected if receiving no response after making
three transmission attempts. In this case, LAC and LNS need to set up a new
Tunnel connection.
This configuration is optional on LNS side.
Perform the following configuration in L2TP group view.
By default, Hello interval is 60 seconds. If this configuration is not performed on
LNS side, LNS will adopt this default value to send Hello packet to the peer end
periodically.
Enabling Mandatory
Local CHAP
Authentication
After LAC performs agent authentication on a user, LNS can authenticate the user
again. The user therefore undergoes authentication twice: once on LAC side and
once on LNS side. Only after both the two authentications succeed, can L2TP
Tunnel be created.
In an L2TP network, LNS side authenticates users in three ways: agent
authentication, mandatory CHAP authentication, and LCP re-negotiation.
Among these three authentication approaches, LCP re-negotiation is of the first
priority. If both LCP re-negotiation and mandatory CHAP authentication are
configured on LNS side, L2TP will choose the former, adopting the authentication
mode configured in the associated virtual template interface.
If only CHAP authentication is configured, LNS will perform CHAP authentication
on users.
To perform mandatory CHAP authentication on LNS side, you must configure
username, password and user authentication and enable AAA on this side.
Mandatory local CHAP authentication is optional on LNS side.
Perform the following configuration in L2TP group view.
Restore default transfer mode of AVP undo tunnel avp-hidden
Table 109 Set the transfer mode of AVP data
Operation Command
Tab le 110 Set Hello interval
Operation Command
Set Hello interval tunnel timer hello hello-interval
Restore the default value of Hello interval undo tunnel timer hello