3Com Router User Manual

L2TP Configuration Examples627
Figure 193   Network Connection Wizard (2)
■Click , and configure the IP address of LNS in the popup dialog box (The 
address is the address of LNS interface connected to the Internet), as shown in 
the following figure.
Figure 194   Network Connection Wizard (3) 

628CHAPTER 43: CONFIGURING L2TP 
■Click  to complete the configuration.
■Double click [Connect Connection to 660046] to start VPN connection. Before 
that, if the dialup connection is not set up, the system will automatically 
prompt you to set up dialup connection. After connection, input the username 
and password that are the same as those configured at LNS side, as shown in 
the following figure.
Figure 195   Connect Connection to 660046
■After the VPN is established, execute ipconfig command in the...

L2TP Configuration Examples629
through the Internet. Through setting up a VPN, the user can have access to the 
information in the internal network.
II. Networking diagram
Figure 196   Networking diagram of an individual user interconnecting headquarters
III. Configuration procedure
1Configuration at the user side
Set up a dialup network, with the same access number as that of Router1, and it 
receives the address assigned by LNS server. Input 
[email protected] as the 
username and 
Hello as the...

630CHAPTER 43: CONFIGURING L2TP 
[Router2] ip pool 1 192.168.0.2 192.168.0.100
bEnable AAA authentication.
[Router2] aaa-enable
[Router2] aaa authentication-scheme ppp default local
cConfigure Virtual-Template 1.
[Router2] interface virtual-template 1
[Router2-Virtual-Template1] ip address 192.168.0.1 255.255.255.0
[Router2-Virtual-Template1] ppp authentication-mode chap
[Router2-Virtual-Template1] remote address pool 1
dConfigure a L2TP group and the related attributes.
[Router2] l2tp enable
[Router2]...

L2TP Configuration Examples631
bAdopt AAA authentication.
[Router1] aaa-enable
[Router1] aaa authentication-scheme ppp default local
[Router1] aaa accounting-scheme optional
cCreate an access control list and specify the encrypted L2TP data.
[Router1] acl 101
[Router1-acl-101] rule permit udp source 202.38.161.1 0.0.0.0 
destination 202.38.161.2 0.0.0.0 destination-port equal 1701
dCreate a transform view, use DES encryption and adopt a transport mode.
[Router1] ipsec proposal l2tptrans...

632CHAPTER 43: CONFIGURING L2TP 
[Router2-ipsec-proposal-l2tptrans] transform esp-new
[Router2-ipsec-proposal-l2tptrans] esp-new encryption-algorithm des
[Router2-ipsec-proposal-l2tptrans] esp-new authentication-algorithm 
sha1-hmac-96
[Router2-ipsec-proposal-l2tptrans] encapsulation-mode transport
fCreate the IPSec policy, use IKE negotiation mode and configure the IKE 
pre-shared-key.
[Router2] ipsec policy l2tpmap 10 isakmp
[Router2-ipsec-policy-l2tpmap-10] ike pre-shared-key l2tp_ipsec 
remote...

Troubleshooting L2TP633
■Errors occur to user name and password set at LAC, or the corresponding user 
information is not set at LNS.
■LNS cannot allocate addresses, e.g., the address pool is set too small, or is not 
set at all.
■The types of tunnel password authentication are inconsistent. Given that the 
default authentication type of VPN connection created by Windows 2000 is 
MSCHAP, if the peer does not support MSCHAP, CHAP is recommended.
Fault 2: After a tunnel is created, the data cannot be...

634CHAPTER 43: CONFIGURING L2TP  

44
CONFIGURING GRE 
This chapter covers the following topics:
■GRE Protocol Overview
■Configuring GRE
■Displaying and Debugging GRE 
■GRE Configuration Example
■Troubleshooting GRE
GRE Protocol 
OverviewThe Generic Routing Encapsulation (GRE) protocol encapsulates datagram of 
network layer protocols, such as IP and IPX, and enables these encapsulated 
datagrams to transmit in another network layer protocol, such as IP. GRE is a Layer 
3 protocol that creates Virtual Private Network (VPN) tunnels. A...

636CHAPTER 44: CONFIGURING GRE 
which examines the key, checksum or message sequence number. After the GRE 
header is removed, the IP message is processed by the IPX protocol in the same 
way as an ordinary datagram.
The system receives a datagram to be encapsulated and routed,. The datagram is 
first encapsulated in the GRE message so that the datagram is the payload of a 
GRE message. Then the datagram is encapsulated in an IP message. The IP layer 
forwards the message. The IP protocol that forwards...