Product manual

Chapter 7: Technology Background
371
CHAPs
Challenge Handshake Authentication Protocol (CHAP) is an authentication
mechanism used to authenticate iSCSI sessions between initiators and targets.
A uni-directional or peer CHAP authenticates from the target (VTrak) to the
initiator (host PC or server).
A bi-directional or local CHAP authenticates target to initiator and initiator to
target.
Portal
A portal is the logical point of connection between the VTrak and the iSCSI
network. Portals use an IP address and a TCP port number to identify an IP
storage resource. VTrak supports up to 32 iSCSI portals per iSCSI port. VTrak
uses TCP port 3260.
VTrak supports both IPv4 and IPv6 addresses. See “Internet Protocols” on
page 373.
Portals on VTrak support three types of port associations:
• PHY – A simple connection through one port.
• VLAN – Virtual Local Area Network. The portal is part of a virtual network.
Used when a dedicated network is not available for iSCSI.
• Trunk – An aggregation of two or more iSCSI ports on the same RAID
controller. Also known as a link aggregation. This feature combines ports to
increase bandwidth.
Once you have made a port association, you cannot change it. If you have no
portals with the port association you want, create a new portal.
Each iSCSI portal can belong to a different VLAN. VTrak supports 32 VLANs.
Port
A port is the physical point of connection between the VTrak and the iSCSI
network. There are four ports on each RAID controller for a total of eight. When
you create a portal, you specify one or more ports. Each port has a unique MAC
address.
There are two options for each iSCSI port:
• Enable Port – Turns the port on or off.
• Jumbo Frame – Enables jumbo frame support on the port.
The standard Ethernet frame is 1518 bytes, with 1500 bytes for payload. A jumbo
frame ranges from 1500 bytes to 9000 bytes of payload. Because jumbo frames
carry more data, they are used to reduce network management overhead,
thereby increasing network throughput.