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Cisco 10000 Series Router Software Configuration Guide
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Chapter 21 Configuring L2VPN Interworking
Ethernet/VLAN to ATM AAL5 Interworking
Figure 21-1 Protocol Stack for ATM AAL5 to Ethernet Local Switching Bridged
Interworking—With VLAN Header
In Cisco IOS Release 12.2(33)SB, the Ethernet/VLAN to ATM AAL5 AToM has the following
restrictions:
• The following translations are only supported and other translations are dropped:
–
Ethernet without LAN FCS (AAAA030080C200070000)
–
Spanning tree (AAAA030080C2000E)
• ATM encapsulation type supported for bridged interworking is aal5snap. However, ATM
encapsulation types supported for routed interworking are aal5snap and mux.
• The existing QoS functionality for ATM is supported, including setting the ATM CLP bit.
• Only ATM AAL5 VC mode is supported. ATM VP and port mode are not supported.
• SVCs are not supported.
• Individual AAL5 ATM cells are assembled into frames before being sent across the pseudowire.
• Non-AAL5 traffic, (such as OAM cells) is punted to be processed at RP level. A VC that has been
configured with OAM cell emulation on the ATM PE router (using the oam-ac emulation-enable
CLI command) can send end-to-end F5 loopback cells at configured intervals toward the CE router.
• When the pseudowire is down, an F5 end-to-end segment AIS/RDI (Alarm indication signal/Remote
defect indication) is sent from the PE router to the CE router.
• If the Ethernet frame arriving from Ethernet CE includes a 802.1Q header (VLAN header), due to
the type of endpoint attachment (Ethernet port mode), the VLAN header stays in the frame across
the pseudowire (
Figure 21-2).
270308
ATM
CE
Eth
CE
ATM Ethernet
PE
ATM Header
MAC Header
DA
SA
MAC Header
DA
SA
Ethertype 81-00
VLAN Tag
Type/Length
Ethertype 81-00
VLAN Tag
Type/Length
Remainder of
MAC Frame
Remainder of
MAC Frame
CPCS - UU CPI
Length
CRC
LAN FCS
LLC (AA-AA)
LLC(03) OUI (00)
OUI (80-C2)
PID (00-07)
PAD (00-00)