MetaFrame XP Presentation Server, Feature Release Updates

Feature Release 2 adds:

• Bandwidth efficiencies

• Bigger TCP window
  and more buffers

• Better utilization of
  maximum packet size

• Improved data compression

• Dropped bandwidth requirements
  by 50% in some cases

• Bulk data channels

• Performance increased with client
  drive mappings, clip board and printing

• Screen traffic remains responsive

Feature Release 3 adds:

• SpeedScreenâ„¢ browser acceleration provides
  a new virtual channel for browser traffic

Router Queuing Settings

Quality of Service (QoS) is the ability to define a level of performance in a data communications system. QoS is most commonly implemented for WAN connections because LANs typically have abundant bandwidth available. A common method for QoS is queuing.

Cisco routers are discussed here because most Citrix MetaFrame XP Presentation Server installations already employ Cisco routers.

On Cisco routers, the commonly available queuing types are:

• First/in/first out (FIFO)

• Weighted Fair Queuing (WFQ)

• Priority Queuing

• Custom Queuing

Cisco also deploys another type of QoS called Network-based application recognition (NBAR). NBAR can be used for ICA traffic and enables a network administrator to identify and classify network traffic based on Citrix published applications.

Network Interface Card Settings

Network interface cards (NICs) are printed circuit boards that plug into the bus of both the client machines and servers in a network. NICs control the transmission and receiving of data at the data link level of the OSI model (Layer 1 (physical) and Layer 2 (data)).

The main techniques to optimize NICs include:

• Manually configuring speed and duplex settings: Most 10/100-based network cards auto-sense the network speed by default. Manually setting these cards to the appropriate link speed and duplex prevents the auto-sensing process from interfering with communication and forces the desired speed. If the server is connected to an auto-sensing device, like a router or switch, apply these settings to this device as well.

• Removing unused protocols: Remove unused protocols on both clients and servers. If only one protocol is installed, then the machine does not have to go through the process of figuring out which protocol to use.

• Changing the binding order of protocols: If more than one protocol must remain on the machine, then change the binding order of protocols based on frequency of use to minimize the time required to choose the correct protocol.

IoPageLockLimit Values

The IoPageLockLimit value specifies the limit of the number of bytes that can be locked for I/O operations. When this value is 0, the system uses the default (512K). Below is a table of values based on server RAM.

Server RAM(MB)	IoPageLockLimit (decimal/bytes)	IoPageLockLimit (hex/bytes)
64-128	4096	1000
256	8192	2000
512	16384	4000
1024	65536	1000

Configuring the Paging File

Remember:

• Always set the paging file initial size to be the same as the maximum size to prevent disk fragmentation of the paging file.

• The optimal size of a paging file is best determined by monitoring the server under a peak load.

OSI model

Open System Interconnection. An ISO standard for worldwide communications that defines a framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.

NTFS

NT File System. The file system that the Windows Server operating system uses for storing and retrieving files on a hard disk.

IIS

Internet Information Server. Web server software from Microsoft that runs under Windows NT. IIS allows the set up of a web site in addition to controlling and managing it remotely through the Internet.

parity

The quality or state of being equal or equivalent.

thrashing

Excessive paging in a virtual memory computer. If programs are not written to run in a virtual memory environment, the operating system may spend excessive amounts of time swapping program pages in and out of the disk.

FIFO

First/in/first out. First-in, first-out simply implies that packets are processed sequentially, with no concern for prioritization. This is the default for LANs and WANs above 2.048 Mbps.

WFQ

Weighted Fair Queuing. Weighted fair queuing is a dynamic prioritization algorithm and is the Cisco default on all interfaces supporting WAN speeds below 2.048 Mbps (E1).

Priority Queuing

Priority Queuing allows priority to be set up on a particular protocol and port number. It is straightforward in that anytime a router receives a packet with that protocol and port number, it is given high, medium, normal or low priority, in that specific order. All high traffic flows first, then all medium traffic and so on.

Custom Queuing

Custom Queuing allows a finite number of bytes of each specified class of traffic to be transmitted by the router. It provides the ability to set up 16 different queues that act in a round robin format.

NBAR

Network-based application recognition. Beginning with the Cisco IOS 12.1(2)E, NBAR was enabled for Citrix ICA traffic. NBAR automatically assumes TCP port 1494 and UDP port 1604 is used for ICA traffic and enables a network administrator to identify and classify network traffic based on Citrix published applications, thus further defining prioritization. NBAR is only effective where published applications exist.

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