C H A P T E R
4-1
Data Center High Availability Clusters Design Guide
OL-12518-01
4
FCIP over IP/MPLS Core
This chapter discusses the transport of Fibre Channel over IP (FCIP) over IP/Multiprotocol Label
Switching (MPLS) networks and addresses the network requirements from a service provider (SP)
perspective. This chapter also describes service architectures and storage service offerings using FCIP
as a primary storage transport mechanism.
Overview
Storage extension solutions offer connectivity between disparate storage “islands,” and promote
transport solutions that are specifically geared towards carrying storage area network (SAN) protocols
over WAN and MAN networks. This emerging demand is providing a new opportunity for carriers. SPs
can now deliver profitable SAN extension services over their existing optical (Synchronous Optical
Network [SONET]/Synchronous Digital Hierarchy [SDH] and Dense Wavelength Division Multiplexing
[DWDM]) or IP infrastructure. DWDM networks are ideal for high-bandwidth, highly resilient networks
and are typically deployed within metro areas. Transporting storage traffic over the existing
SONET/SDH infrastructure allows SPs to maximize the use of their existing SONET/SDH ring
deployments. Some applications do not mandate stringent requirements offered by optical networks.
These applications can be easily transported over IP networks using FCIP interfaces. The obvious
advantage of transporting storage over IP is the ubiquitous nature of IP.
Disk replication is the primary type of application that runs over an extended SAN network for business
continuance or disaster recovery. The two main types of disk replication are array-based (provided by
EMC
2
SRDF, Hitachi True Copy, IBM PPRC XD, or HP DRM, and host-based (for example, Veritas
Volume Replicator). Both disk replication types run in synchronous and asynchronous modes. In
synchronous mode, an acknowledgement of a host-disk write is not sent until a copy of the data to the
remote array is completed. In asynchronous mode, host-disk writes are acknowledged before the copy
of the data to the remote array is completed.
Applications that use synchronous replication are highly sensitive to response delays and might not work
with slow-speed or high-latency links. It is important to consider the network requirements carefully
when deploying FCIP in a synchronous implementation. Asynchronous deployments of FCIP are
recommended in networks with latency or congestion issues. With FCIP, Fibre Channel SAN can be
extended anywhere an IP network exists and the required bandwidth is available. FCIP can be extended
over metro, campus, or intercontinental distances using MPLS networks. FCIP may be an ideal choice
for intercontinental and coast-to-coast extension of SAN.
