4.1.1 Classical IP over ATM (CLIPoA)
TCP
IP
AAL5
ATM
25.6
ATU-R
ADSL
DSLAM
ATM-VC
ISP
TCP
IP
AAL5
ATM
ATM25
ATM
ATM
ADSL
OC-3
ATM
Figure 53 Classical IP over ATM
Classical IP over ATM is an IETF protocol which uses ATM’s high
speed ability in the Local Area Network. It uses ATMF (ATM25.6)
physical interface over Twisted Pair Cable (per ATM Forum) to
interconnect in the LAN at the speed of 25.6 Mbps.
Classical IP over ATM reduces overhead by having IP and ARP
datagrams encapsulated in AAL5 using IETF RFC 1483 LLC/
SNAP encapsulation.
4.1.2 Ethernet Frames over ATM (EoA)
In this case, the Ethernet frames are encapsulated into the ATM
Adaptation Layer 5 (AAL5) using RFC 1483. The encapsulation
supports both routing and bridged. This is based on the standard
RFC 1483 ‘Multi protocol Encapsulation over AAL 5’.
Figure 54 shows a sample configuration of Ethernet over ATM
used in the field. In this case, IP address management can be
static with RFC 1483 Bridge encapsulation, dynamic with the use
of DHCP session management or it can use RFC 1483 Routed.
ISP
ATU-R
ATM-VC
B-RAS
IP
802.3
1483
IP
AAL5
DSLAM
ATM
1483
AAL5
ATM
IP Routing
802.3
WAN Media
802.3
ADSL
ADSL
OC-3
OC-3
LAN Media
Figure 54 Ethernet over ATM
MTT-14B e_Manual D07-00-083P RevA00
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