Cisco DS-C9216I-K9 Configuration Manual page 48

Software Features
Trunking
Trunking is the term used to refer to an ISL link that carries one or more VSANs. Trunking ports receive
and transmit Extended ISL (EISL) frames. EISL frames carry an EISL header containing VSAN
information. Once EISL is enabled on an E port, that port becomes a TE port. The trunking configuration
is saved along with the interface information.
PortChannels
PortChannel refers to the aggregation of multiple physical Fibre Channel ports into one logical port to
provide high aggregated bandwidth, load balancing, and link redundancy. Up to 16 physical ports can be
aggregated into a PortChannel. PortChannels can connect to ports across switching modules. The failure
of a port in one switching module does not bring down the logical PortChannel link. Specifically, a
PortChannel does the following:
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IP Services
Switches in the Cisco MDS 9000 Family support the following IP services:
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Cisco MDS 9000 Fabric Manager Switch Configuration Guide
1-6
Increases the aggregate bandwidth on an ISL or EISL by distributing traffic among all functional
links in the channel.
Load balances across multiple links and maintains optimum bandwidth utilization. Load balancing
is based on a source ID (SID), destination ID (DID), and optionally the originator exchange ID (OX
ID) that identify the flow of the frame.
Provides high availability on an ISL. If one link fails, traffic previously carried on this link is
switched to the remaining links. If a link goes down in a PortChannel, the upper protocol is not
aware of it. To the upper protocol, the link is still there, although the bandwidth is diminished. The
routing tables are not affected by link failure. PortChannels can contain up to 16 physical links and
can span multiple modules for added high availability.
IP over Ethernet—These services are limited to management traffic.
IP over Fibre Channel (IPFC)—IPFC (RFC 2625) specifies how IP packets are transported using
encapsulation schemes. By encapsulating IP frames into Fibre Channel frames, management
information is exchanged among switches without requiring a separate Ethernet connection to each
switch. Each switch includes:
– Encapsulation for IP and Address Resolution Protocol (ARP) over Fibre Channel.
– Address resolution uses the ARP server.
IP routing services—These services include:
Ethernet or TCP/IP connection.
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Static IP routing services to enable management traffic between VSANs.
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DNS client support.
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The Network Time Protocol (NTP) server synchronizes the system clocks of network devices.
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Chapter 1 Product Overview
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