16-9
Cisco ONS 15310-CL Ethernet Card Software Feature and Configuration Guide, R5.0
June 2005
Chapter 16 CE-100T-8 Ethernet Operation
CE-100T-8 SONET Circuits and Features
CE-100T-8 VCAT Characteristics
The ML-100T-8 card and the CE-100T-8 card (both the ONS 15310-CL version and the ONS 15454
SONET/SDH version) have hardware-based support for the ITU-T G.7042 standard link capacity
adjustment scheme (LCAS). This allows the user to dynamically resize a high order or low order VCAT
circuit through CTC or TL1 without affecting other members of the VCG (errorless). ML-100T-8 LCAS
support is high order only and is limited to a two member VCG.
The ONS 15454 SONET/SDH ML-Series card has a software-based LCAS (SW-LCAS) scheme. This
scheme is also supported by both the ML-100T-8 card and both versions of the CE-100T-8, but only for
circuits terminating on a ONS 15454 SONET/SDH ML-Series card.
The CE-100T-8 card allows independent routing and protection preferences for each member of a VCAT
circuit. The user can also control the amount of VCAT circuit capacity that is fully protected, unprotected
or if the circuit is on a bidirectional line switched ring (BLSR), uses protection channel access (PCA).
Alarms are supported on a per-member as well as per virtual concatenation group (VCG) basis.
Note
The maximum tolerable VCAT differential delay for the CE-100T-8 is 48 milliseconds. The VCAT
differential delay is the relative arrival time measurement between members of a virtual concatenation
group (VCG).
CE-100T-8 POS Encapsulation, Framing, and CRC
The CE-100T-8 uses Cisco EoS LEX (LEX). LEX is the primary encapsulation of ONS Ethernet cards.
In this encapsulation the protocol field is set to the values specified in Internet Engineering Task Force
(IETF) Request For Comments (RFC) 1841. The user can provision GPF-F framing (default) or
high-level data link control (HDLC) framing. With GFP-F framing, the user can also configure a 32-bit
CRC (the default) or no CRC (none). When LEX is used over GFP-F it is standard Mapped Ethernet over
GFP-F according to ITU-T G.7041. HDLC framing provides a set 32-bit CRC.
Figure 16-5
illustrates CE-100T-8 framing and encapsulation.
Figure 16-5 ONS CE-100T-8 Encapsulation and Framing Options
SONET/SDH Frame
SONET/SDH Payload Envelope
Transport Overhead
LEX
HDLC Framing Mode
GFP-F Framing Mode
Flag
Address Control Protocol
Payload
FCS
or
Encapsulation
GFP-Mapped
Ethernet (LEX)
GFP-F Frame Types
115444
Core
Header
Payload
Header
Payload
FCS
