Lex; Figure 20-2 Rpr Data Frames; Figure 20-3 Lex Under Hdlc Framing - Cisco ONS 15454 SDH Configuration Manual

Chapter 20 POS on ONS Ethernet Cards
Figure 20-2 RPR Data Frames
Basic Data Frame
1
TTL to Dest
1 Base Control
6 MAC da
6 MAC sa
1 TTL Base
1 Extended Control
2 hec
2 Protocol Type
n Service Data Unit
4 FCS

LEX

The Cisco EoS LEX is the primary encapsulation of ONS Ethernet cards. This encapsulation is used
under HDLC framing, and the protocol field is set to the values specified in Internet Engineering Task
Force (IETF) Request For Comments (RFC) 1841. Under GFP-F framing, the Cisco IOS CLI also uses
the keyword lex. With GFP-F framing, the lex keyword is used to represent standard mapped Ethernet
over GFP-F according to ITU-T G.7041.
Figure 20-3
LEX is supported by all the ONS Ethernet cards, except the ONS 15454 and ONS 15454 SDH E-Series
cards.
Figure 20-3 LEX Under HDLC Framing
1 byte 1 byte 1 byte 2 bytes
Flag Addr Control Protocol
0x7E 0xFF 0x03 0x0041
Proprietary
7 bytes
Preamble
Header
Payload
Trailer
illustrates EoS LEX under HDLC framing.
Ethernet Payload
1 byte 6 bytes 6 bytes 2 bytes
SFD DA SA Ln/EType
Cisco ONS 15454 and Cisco ONS 15454 SDH Ethernet Card Software Feature and Configuration Guide, R8.0
Extended Data Frame
1 TTL to Dest
Base Control
1
6 MAC da
6 MAC sa
1 TTL Base
1 Extended Control
2 hec
6 Extended DA
6 Extended SA
2 Protocol Type
n
Service Data Unit
4 FCS
46-1500 bytes* 4 bytes
Data/Pad FCS
Header
Payload
Trailer
4 bytes 1 byte
CRC Flag
0x7E
LEX
20-5