Buffalo NAS Transfer Rates

I've been playing around with a Buffalo NAS storage device recenetly and realised that the write speeds are much slower than the read speeds. When moving data off the device which is essentially a copy and delete the transfer rate is around 6-7 mega bits per second. However when I move data to back to it which is essentially a write function and delete, the transfer rate is only 1.6 mega bits per second.

Slow To Copy Files From NAS

I recently has an issue where trying to copy video files between my main PC and NAS drive was extremely slow, around 300k/sec. I'm using a Netgear N wireless router and a generic N wireless network USB stick on the PC so would expect around 6 tp 7 meg/sec. My setup is that the NAS is cabled directly to the modem router so all devices in the house can access it equally as fast and the slowest part bottleneck should be the wireless.

After playing with all the wireless settings I could think of and even buying a new wireless USB stick the problem still persisted. Finally I replaced the LAN cable joining the NAS and the router and what do you know, suddendly all the devices in the house can transfer files at the expected speed. It turned out to be a faulty LAN cable.

Then I remembered the old OSI table and how you should always trouble shoot from the lowest level first and work your way up. IE check power, cables and hardware first, then play with software. Hopefully this may help someone if they are having similar issues.

Password Recovery for Catalyst 3500XL Series Switch

This is the procedure I used to recover the password for a Cisco Catalyst 3500XL series switch

1. Attach a cisco configuration cable to the console port of the switch and a com port on a PC. start up hyperterminal and use the following terminal settings:
   Bits per second (baud): 9600
   Data bits: 8
   Parity: None
   Stop bits: 1
   Flow Control: Xon/Xoff

2. Unplug the power cable.

3. Hold down the mode button located on the left side of the front panel, and reconnecting the power cable.

   Release the mode button after the LED above Port 1x goes out.

   You'll see the following instructions appear:

   The system has been interrupted prior to initializing the
   flash filesystem.  The following commands will initialize
   the flash filesystem, and finish loading the operating
   system software:
       flash_init
       load_helper
       boot
   switch:
   
   

4. Issue the flash_init command.

   switch: flash_init
   Initializing Flash...
   flashfs[0]: 143 files, 4 directories
   flashfs[0]: 0 orphaned files, 0 orphaned directories
   flashfs[0]: Total bytes: 3612672
   flashfs[0]: Bytes used: 2729472
   flashfs[0]: Bytes available: 883200
   flashfs[0]: flashfs fsck took 86 seconds
   ....done Initializing Flash.
   Boot Sector Filesystem (bs:) installed, fsid: 3
   Parameter Block Filesystem (pb:) installed, fsid: 4
   switch:
   
   

5. Issue the load_helper command.

   switch: load_helper
   switch:

6. Type the command dir flash: command.

   The switch file system is displayed something like this:

   switch: dir flash:
   Directory of flash:/
   2    -rwx  1803357   <date>               c3500xl-c3h2s-mz.120-5.WC7.bin
   4    -rwx  1131      <date>               config.text
   5    -rwx  109       <date>               info
   6    -rwx  389       <date>               env_vars
   7    drwx  640       <date>               html
   18   -rwx  109       <date>               info.ver
   403968 bytes available (3208704 bytes used)
   switch:
   
   

7. Type rename flash:\config.text flash:\config.old to rename the configuration file. There's no output shown if the command is successful

   switch: rename flash:\config.text flash:\config.old
   switch:
   
   

    

8. Type the boot command to boot the system.

   switch: boot
   Loading "flash:c3500xl-c3h2s-mz.120-5.WC7.bin"...###############################
   ################################################################################
   ######################################################################
   File "flash:c3500xl-c3h2s-mz.120-5.WC7.bin" uncompressed and installed, entry po
   int: 0x3000
   executing...
   
   

9. Enter "n" at the prompt to skip the setup wizard

10. At the switch prompt type en to enter enable mode.

    Switch>en
    Switch#

11. Type rename flash:config.old flash:config.text to rename the configuration file with its original name.

    Switch#rename flash:config.old flash:config.text
    Destination filename [config.text] 
    Switch#
    

12. Copy the configuration file into memory:

    Switch#copy flash:config.text system:running-config
    Destination filename [running-config]? 
    1131 bytes copied in 0.760 secs
    Switch#
    

    The configuration file is now reloaded.

13. Change the password:

    Switch#configure terminal
    Switch(config)#no enable secret 
     !--- This step is necessary if the switch had an enable secret password. 
    Switch(config)#enable password Cisco
    Switch#(config)#^Z 
     !--- Control/Z. 
    

14. Write the running configuration to the configuration file with the write memory command:

    Switch#write memory
    Building configuration...
    [OK]
    Switch#

Benefits of Using NAS to Backup Data

There are many ways to backup data. Most people have an external hard drive and copy their douments and photos across to it every now and then. Or you might have some backup software running that automates the process. The problem with these solutions is that the external hard usually sits on the same desk where the PC is located. If there is ever a break in and the PC is stolen, there is a good chance they'll swipe the external hard drive as well. Likewise if there is a fire, it will likely engulf your PC and backup hard disk.

A NAS drive, or Network Area Storage drive allows the external hard disk to be located elsewhere in the house. Because its physically in a different location the chances of it being stolen or damged at the same time as your PC are greatly reduced. Especially if you get creative and position in a place thats difficult to spot.

In order to keep cost down, many NAS drives do not have wireless capabilities and rely on an ethernet cable which connects the NAS to your home modem/router. From there it can be accessed by all the other PC's and mobile devices in the house. However if you spend a bit more and get one with wireless capability, you can have more flexibility as to where you position it in the house. As long as there's a power point nearby, it could go anywhere including on top of kitchen cupboards, in the bedroom out of sight, or anywhere you can think of thats securely away from sight.

Another advantage of NAS drives is built in redundancy. The models that hold two hard disks usually offer RAID 1, meaning that each disk is a copy of the other. So if one disk fails, the other is still available. When you replace the faulty one, it rebuilds itself and data is ever lost. Larger NAS drives that hold four or more hard disks offer RAID 5. Raid 5 requies a minimum of four hard disks and one is used for redundancy and total of the remaining disks is your available disk space.

If a house or business has more than one PC and a number of mobile devices such as smart phones and portable media players, the NAS could instead be used as a central repository where all these devices can access and use the same data. Because the NAS uses less power than a PC, everything else in the house can still use the data without the PC having to be on, therefore saving on power costs. For example you might want to show friends some photos on the TV, and with the photos stored on the NAS there is no need to boot up the PC.

These NAS best practices are just some things you can do with network storage. Some also have built in BitTorrent clients, or they may have DLNA which allows media streaming. However the best thing they do is improve the security of backups. Configured properly and safely positioned in the house, a NAS drive provides additional peace of mind that your data is securely backup up and seperated from your everyday PC.

Frame Relay Cheat Sheet

Frame Relay Discard Eligability (DE)

The DE bit is used to indicate the frame has a lower importance than other frames. The DE bit is part of the address field in the address header. Sending devices can set the DE bit to 1 to indicate lower importance.

FECN - Forward-Explicit Notification for the receiver that the path is congested

BECN - Backward-Explicit Notification for the sender that the path is congested

PVC Status

The DCE(switch) reports the status and the DTE (router) recieves the status. The status is exchanged via the LMI protocol. The statuses are:

• Active - PVC configured correctly 
• Inactive - PVC configured correctly at local switch but down at the other end
• Deleted - PVC is not present

LMI is the signalling between the frame relay switch and the router. The 3 types of LMI are Cisco(default), ANSI and Q933A

Sub Interfaces

Two types of sub interfaces can be created for frame relay.

Multipoint and point-to-point. A multipoint sub interface can handle multiple PVCs

Point-to-point sub interface turns every PVC into a point-to-point network with its own network addressing. Using point-to-point sub interfaces gives greater control over our frame relay network.

Troubleshooting

When performing a loopback test put the interface encapsulation to HDLC

Network Encapsulation Types

WAN Layer 2 Encapsulation

HDLC, PPP and Frame relay are used for WAN Layer 2

On serial links, Cisco uses proprietry encapsulation HDLC by default. Use PPP with other non Cisco routers.

• HDLC is the default serial protocol and is Cisco propriety
• PPP is multivendor and uses the sub protocol LCP (Link Control Protocol) 

On frame relay links  - Cisco uses prorpietry encapsulation Cisco by default. Use IETF with other non Cisco routers.

LAN Layer 2 Encapsulation

Ethernet, Token Ring, FDDI are used for LAN Layer 2

VLAN Trunking Protocols

802.1q

ISL - (Cisco Inter-Switch Link), an older VLAN trunking protocol that is proprietary to Cisco

Routing Protocol Comparisons

Read more: Routing Protocol Comparisons

EIGRP Cheat Sheet

EIGRP is a Cisco propriety routing protocol.

EIGRP stores all route information in it's topology table. From there it chooses the primary best route and puts it in the routing table. This best route is called the Successor route. It's the primary route used and is installed in the routing table. Any backup routes that could be used in the AS without causing loops are called feasible successors. These remain in the topology table.

Read more: EIGRP Cheat Sheet

Point to Point Protocol Cheat Sheet

CHAP is a one way authentication method. CHAP uses a 3-way handshake process to perform one-way authentication.

Using CHAP in both directions creates a 2 way authentication. So that means there is a 3 way handshake in both directions.

Read more: Point to Point Protocol Cheat Sheet

What is Cloud Computing?

When talking about cloud computing the word 'cloud' can be thought as meaning 'internet'. So what does internet computing mean? It sounds exciting but really it just means that you are outsourcing your processing power and storage to third parties who happen to be connected to you over the internet. Not surprisingly the main players of the internet; Google, Microsoft, HP, AT&T are also the main providers of cloud computing.

Read more: What is Cloud Computing?