Chapter 4 FCIP over IP/MPLS Core

Using FCIP Tape Acceleration

FCIP Tape Acceleration maintains data integrity in the event of a variety of error conditions. Link errors and resets are handled through Fibre Channel-tape Ethernet LAN services (ELS) recovery mechanisms. Should the remote tape unit signal an error for an I/O that the status has already been returned to “good”, a Deferred Error is signaled to the tape backup application. The backup application either corrects the error and replays the command or rolls back to the previous file mark and replays all I/Os from that point.

You can enable FCIP Tape Acceleration on any FCIP interface on the Cisco IPS-4, IPS-8, and MPS-14/2 modules, or the Gigabit Ethernet interfaces on the Cisco MDS 9216i.

FCIP

FCIP encapsulates Fibre Channel frames and transports these frames within TCP packets. The FCIP tunnel acts as an Inter-Switch Link (ISL) between two fabric switches. The endpoint devices detect each other as they would between two local switches interconnected with standard ISL. FCIP endpoints are associated to virtual e-ports and these ports communicate with themselves and exchange information such as reconfigure fabric (RCF), Fabric Shortest Path First (FSPF), build fabric (BF), and so on. FCIP relies on the TCP/IP protocol to provide contention control and orderly delivery of packets. Figure 4-3shows the FCIP encapsulation process.

Figure 4-3

FCIP Encapsulation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IP

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FCIP

 

 

 

 

 

 

 

 

FC

 

 

 

 

 

 

 

 

SCSI

 

 

 

 

 

 

 

 

Data

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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TCP Operations

TCP implemented on traditional servers or hosts tends to overreact to packet drops. The throttling back that occurs in the traditional TCP implementation is not acceptable to storage traffic. The TCP stack implemented for FCIP (in the Cisco MDS 9000) is optimized for carrying storage traffic by reducing the probability of drops and increasing the resilience to drops when they occur.

Fibre Channel traffic can be highly bursty, and traditional TCP can amplify that burstiness. With traditional TCP, the network must absorb these bursts through buffering in switches and routers. Packet drops occur when there is insufficient buffering at these intermediate points. To reduce the probability of drops, the FCIP TCP implementation reduces the burstiness of the TCP traffic that leaves the Gigabit Ethernet interface.

In the FCIP TCP stack, burstiness is limited through the use of variable rate, per-flow shaping, and by controlling the TCP congestion window size. After idle or partially idle periods, the FCIP interface does not send large packet bursts at Gigabit interface speeds. If not controlled, large Gigabit Ethernet bursts can overflow downstream routers or switches and speed mismatches can occur. For example, a Gigabit Ethernet feeding into a DS3 (45 Mbps) link through a router may overflow the router buffers unless the traffic is controlled or shaped in a way that the router can handle the transmission.

TCP Parameters

TCP parameters may require adjustments when implementing SAN extension that uses FCIP. This section provides general information and recommendations for key TCP parameters that require adjustments. The following parameters are considered:

Data Center High Availability Clusters Design Guide

4-8

OL-12518-01

 

 

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Cisco Systems OL-12518-01 manual TCP Operations, TCP Parameters
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OL-12518-01 specifications

Cisco Systems OL-12518-01, also known as the Cisco Management Services for Wireless LAN Controller, is a key component for businesses seeking to enhance their wireless networking capabilities. This product offers a comprehensive management solution designed to ensure high performance and security of wireless networks.

One of the main features of OL-12518-01 is its centralized management interface, which simplifies the deployment and operation of multiple access points across an organization. This centralized approach allows network administrators to manage all wireless devices from a single pane of glass, significantly improving operational efficiency and reducing the potential for human error.

The product is built upon various robust technologies that enhance its performance. It includes advanced features like Quality of Service (QoS) support, which prioritizes bandwidth for critical applications. This ensures that mission-critical operations run smoothly, even in environments with high user density. Furthermore, the Wireless LAN Controller supports a variety of security protocols, including WPA3, ensuring that user data and wireless networks are protected against unauthorized access.

A significant characteristic of OL-12518-01 is its scalability. As businesses grow, their network requirements can change dramatically. The Cisco Management Services solution is designed to scale easily alongside the organization’s needs, allowing for the addition of more access points and the integration of advanced features seamlessly. This adaptability makes it suitable for both small businesses and large enterprises, ensuring consistent wireless connectivity across diverse spaces.

Moreover, OL-12518-01 features robust analytics and reporting capabilities. It provides valuable insights into network performance and user behavior, enabling administrators to make informed decisions about resource allocation and troubleshooting. With real-time monitoring tools, IT staff can quickly identify and resolve issues, minimizing downtime and enhancing overall user experience.

In summary, Cisco Systems OL-12518-01 is a powerful wireless LAN management solution that combines centralized management, advanced security features, scalability, and comprehensive analytics. These characteristics make it an ideal choice for organizations aiming to optimize their wireless networking performance while ensuring security and reliability in their operations. By investing in OL-12518-01, businesses can achieve a robust wireless infrastructure that meets their current and future needs.
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