FortiGate
FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
mmishra_FTNT
Staff
Staff
Article Id 198623

Description

 
This article describes how to enable IPOA connection type on ADSL devices on a FortiGate used over ATM.


Scope

 
All FortiGate ADSL devices.


Solution

 
This is an explanation of different connection types used for ADSL connection over ATM:

PPPoA.

The logical choice for enabling individual clients to gain internet access over an ATM-based network. The PPP layer is introduced in order to make use of the already very popular features of PPP, such as authentication, link monitoring, IP address assignment, DNS address assignment. The exact format of the RFC 1483 header put onto the PPP packets is defined in RFC 2364.

PPPoE.

The logical choice for enabling individual clients to gain internet access over an Ethernet-based network (but it is even used over ATM-based networks). As with PPPoA, it gets all the advantages of PPP, but at the cost of some extra packet overhead. The PPPoE packets are encapsulated using the RFC 1483 Bridged method.

IPoA.

Designed in an attempt to make IP subnets map directly onto ATM networks in the same way that IP subnets map onto VLANs. So, an ATM address resolution protocol was introduced that enabled the IP stack to obtain the IP address for another IP host connected to its local ATM subnet (RFC 2225). The structure required to make this kind of network operate is rather complex, mostly because trying to make a channel-oriented transport like ATM appear like a broadcast domain is not a very natural fit.

RFC 1483 Bridged.

The whole Ethernet packet that arrives on the Ethernet side of the ADSL modem is encapsulated into AAL5 using the 'bridged-data' format defined in RFC 1483 and sent on the ADSL line. The modem forwards packets based on their MAC addresses, that is, it bridges the packets.

RFC 1483 Routed.

The whole Ethernet packet that arrives on the Ethernet side of the ADSL modem is encapsulated into AAL5 using the 'bridged-data' format defined in RFC 1483 and sent on the ADSL line. The modem forwards packets based on their IP addresses; that is, it routes the packets.

To enable IPOA on FortiGate ADSL devices use the following commands:
 
FortiOS 6.4.
config system interface
    edit dsl
        set mode pppoa
        set tc-mode atm
end
 
Older FortiOS versions.
config system interface
    edit adsl
        set atm-protocol ipoa
end