Cisco 15327 - Manual (Page 337)

20-5
Ethernet Card Software Feature and Configuration Guide, R7.2
Chapter 20 POS on ONS Ethernet Cards
LEX
Figure 20-2 RPR Data Frames
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 illustrates EoS LEX under HDLC framing.
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 TTL to Dest
Base Control
FCS
Service Data Unit
Protocol Type
MAC da
TTL Base
MAC sa
Extended Control
hec
6
1
1
6
1
2
2
n
4
Header
Payload
Trailer
1
6
1
1
6
1
2
6
6
2
TTL to Dest
Base Control
Protocol Type
Extended SA
Extended DA
MAC da
TTL Base
MAC sa
Extended Control
hec
FCS
Service Data Unit n
4
Header
Payload
Trailer
Basic Data Frame
Extended Data Frame
151965
Addr Flag
1 byte
Control Protocol
1 byte 1 byte 2 bytes
Data/Pad FCS SA DA SFD Preamble
4 bytes 1 byte 7 bytes 6 bytes 6 bytes 2 bytes
Ethernet Payload CRC
0x7E
Flag
1 byte
0x7E
4 bytes
0xFF 0x03 0x0041
Proprietary
46-1500 bytes*
Ln/EType
115433