ATM AAL5 encapsulation

• Ingress reassembles AAL5 frames and strips 8 octet AAL5 trailer

• Required control word includes:

  • Transport type (AAL5 CPCS-PDU or ATM cell)
  • EFCI, CLP, and C/R bits (CPCS-UU’s LSB)
  • (CPCS-PDU + control word) length
  • Sequence number

Tunnel

label

VC

label

4 octets

4 octets

Control

word

AAL5 CPCS-PDU

4 octets

Rsvd

T

E

L

C

bits

4

1

1

1

1

Length

8

Sequence Number

16

Control Word

AAL5 over MPLS

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