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Cisco Systems ONS 15600 manual Autonegotiation, 10-7

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Chapter 10 Ethernet Operation

10.6 Autonegotiation

flow control, it generates and obeys pause frames. When it uses asymmetric flow control, it only generates pause frames. Through management control, the Ethernet interface allows an operator to turn flow control ON or OFF (the default is ON).

When an Ethernet interface is set to be capable of generating PAUSE frames, it starts generating them at a rate of X PAUSE frames per second when the ingress buffer passes above a certain level called the High Water Mark. A PAUSE_TIME is specified in each PAUSE frame. The values of the PAUSE_TIME parameter and the rate X parameter are determined by the system and are not user settable.

It is expected that the peer Ethernet interface stops sending new frames after receiving a PAUSE frame for the amount of time as specified in the PAUSE_TIME. When an Ethernet interface is actively generating PAUSE frames, it stops generating them when the ingress buffer passes below a certain level, called the Low Water Mark. It is expected that the peer Ethernet interface starts sending new frames after the PAUSE frames stop.

When an Ethernet interface is set to be capable of receiving PAUSE frames, it temporarily suspends transmission of any new Ethernet frames upon reception of a PAUSE frame from its peer. Note that the transmission of any Ethernet frames already begun are completed.

When an Ethernet interface has temporarily PAUSED transmission of Ethernet frames, it resumes transmission of the frames when no new PAUSE frame is received within the PAUSE_TIME specified in the last received PAUSE frame.

The High Water Mark and Low Water Mark values are both operator provisionable. Legal values are as follows:

•Low Water Mark: from 10 kB to 74 kB

•High Water Mark: from 11 kB to 75 kB

The Low Water Mark is always lower than the High Water Mark.

The ASAP line card utilizes tail drop when frames need to be dropped. This means that the last frames received are the first to be dropped. This is implemented with a Last In First Out (LIFO) buffer.

10.6 Autonegotiation

The Ethernet interfaces on the ASAP card are capable of autonegotiating for full duplex (only) operation as per IEEE 802.3z. The default provisioning is to autonegotiate the duplex mode and persists in memory. Autonegotiation can be provisioned to be ON or OFF.

When flow control is turned on (and so is autonegotiation), the Ethernet interface autonegotiates and advertises all modes that it supports. The mode used by the Ethernet interface is the one agreed to by the Ethernet peers. If an agreement on the supported flow control mode cannot be reached, the transmitter is turned off. Autonegotiation is depicted in Figure 10-4.

Cisco ONS 15600 Reference Manual, R7.2

10-7

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Cisco Systems ONS 15600 manual Autonegotiation, 10-7
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ONS 15600 specifications

Cisco Systems ONS 15600 is a highly versatile optical networking platform designed to meet the demands of modern telecommunications and data services. This multiservice edge platform supports various transmission mediums and offers a wide array of features that enable efficient data transport. Ideal for service providers and large enterprises, the ONS 15600 is engineered to provide scalable and reliable optical transport solutions.

One of the notable features of the ONS 15600 is its capability to support multiple protocols, including SONET/SDH, Ethernet, OTN, and legacy TDM services. This flexibility allows users to tailor their networks according to specific service requirements while ensuring interoperability with existing infrastructure. The platform is designed to facilitate seamless service migration, accommodating both legacy and next-generation services.

The modular architecture of the ONS 15600 enhances its scalability. It allows for easy expansion by incorporating additional line cards or interface modules without requiring significant downtime. This modularity ensures that service providers can evolve their networks over time, responding to increasing bandwidth demands and new service offerings with ease.

Incorporating advanced technologies, the ONS 15600 employs Dense Wavelength Division Multiplexing (DWDM), significantly increasing the capacity of fiber networks by allowing multiple signals to be transmitted simultaneously over a single optical fiber. This capability helps to optimize fiber utilization and reduce operational costs. In addition, the platform supports Optical Transport Network (OTN) for improved error detection and correction, contributing to higher reliability and performance.

Another key characteristic of the ONS 15600 is its robust management capabilities. The platform can be managed through Cisco's Optical Networking Manager (ONM), providing a centralized interface for network configuration, monitoring, and troubleshooting. This enhances operational efficiency and minimizes downtime, allowing service providers to focus on delivering quality services to their customers.

The ONS 15600 also prioritizes security, offering various features like encryption and access control to safeguard sensitive data during transmission. With its combination of scalability, flexibility, and security, the Cisco ONS 15600 stands out as a reliable choice for organizations looking to enhance their optical networking capabilities while meeting the evolving demands of the digital landscape. Its commitment to quality and performance makes it a cornerstone of modern optical networks.