Key differences are

1. “truncate” uses DDL and is fast while “delete” doesn’t and hence slower (depending on the number of records).
2. “truncate” resets the auto increment counter while “delete” doesn’t.

Let’s use this test table with just 2 columns uID and username. uID is set to auto_increment.

mysql> SELECT * FROM users;
+-----+----------+
| uID | username |
+-----+----------+
|   1 | Joe      |
|   2 | Foo      |
|   3 | Alan     |
|   4 | Martin   |
+-----+----------+
4 rows in set (0.00 sec)

WARNING: Make sure you know what you are doing. You are doing this at your risk!!!

1. Delete all records in a database table using “truncate”

mysql> TRUNCATE users;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT * FROM users;
Empty set (0.00 sec)

Now, lets insert records and see where the uID value starts

mysql> INSERT INTO users (username) VALUES ('Joe'),('Foo'),('Alan'),('Martin');
Query OK, 4 rows affected (0.00 sec)
Records: 4 Duplicates: 0 Warnings: 0

mysql> SELECT * FROM users;
+-----+----------+
| uID | username |
+-----+----------+
|   1 | Joe      |
|   2 | Foo      |
|   3 | Alan     |
|   4 | Martin   |
+-----+----------+
4 rows in set (0.00 sec)

You can see the uID starts from “1” again.

2. Delete all records in a database table using “delete”

mysql> DELETE FROM users;
Query OK, 4 rows affected (0.00 sec)

mysql> SELECT * FROM users;
Empty set (0.00 sec)

Now, lets insert records and see where the uID value starts

mysql> INSERT INTO users (username) VALUES ('Joe'),('Foo'),('Alan'),('Martin');
Query OK, 4 rows affected (0.00 sec)
Records: 4 Duplicates: 0 Warnings: 0

mysql> SELECT * FROM users;
+-----+----------+
| uID | username |
+-----+----------+
|   5 | Joe      |
|   6 | Foo      |
|   7 | Alan     |
|   8 | Martin   |
+-----+----------+
4 rows in set (0.00 sec)

There you can see the uID column is auto_increment is not reset and continues from the next value of “5”.

'string'[:-n]

or

stringVariable[:-n]

For example, to remove the last character (n=1)

[sai@c7test ~]$ python
Python 2.7.5 (default, Nov 20 2015, 02:00:19)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 'python'[:-1]
'pytho'
>>>
>>> tmpVar = 'Python'
>>> tmpVar[:-1]
'Pytho'
>>>

To make a block select in PuTTY, click and hold “ALT” and then left-click and drag on your mouse. This will make block selection.

If you want to make this the default behaviour,

1. Load a saved session or load “Default Settings”.
2. In the left pane, click Window – Selection.
3. In the right pane, select “Rectangular Block” under Default Selection mode.
4. Click Sessions and save the loaded session.
5. Repeat the above for every saved session.

The following procedure will help you change this default behaviour to prompt to paste than pasting automatically when you right-click.

1. Open PuTTY, in the left-pane, click Selection under Window.
2. In the right-pane select the radio button for “Windows (Middle extends, Right brings up menu)”.
3. Click Session in the left pane, select “Default Settings” and click Save.

Now, for every saved session, select and load and follow the above (in step3, instead of default session, choose your saved session).

If you want to enable it back, follow the procedure and in step 3, choose radio button for “Compromise (Middle Extends, Right Pastes)”.

To change the HOST Key,

1. Launch Oracle Virtual\box Manager.
2. Click File – Preferences.
3. Click Input in the left pane and click “Virtual Machine” tab on the right.
4. Click on the Shortcut field for “Host Key Combination” and click the erase icon that gets highlighted.
5. Now click the Shortcut field again click the key you want to assign (say “ALT”) and click OK.

Using a Generic Proxy forces it to use Passive Mode connections.However, if you need to use Active mode FTP connections then FTP Proxy should be configured.

Click Edit – Settings from menu to open the FileZilla client settings. Expand FTP in the leftpane and click “FTP Proxy“.In the rightpane, select “custom” under “Type of FTP Proxy” and enter the following format specifications:

USER %u@%h
PASS %P
ACCT %w

Once done, enter the IP Address/Hostname and of the Proxy host (if it is not listening on the standard TCP/21 then provide the prot number along with the IP address or hostname, ex: proxy:8085) then the user (username@domainname where domainname is name of the Windows Domain, if it uses WSSO or Intergrated Windows Authentication) and the password (domain password if using windows domain name as above)

This should set the configs appropriately. To check if the connection works OK, try connecting to the external FTP server and you should be able to first connect to the BlueCoat proxy where it first issues a Welcome message as in the following screenshot before it connects you to the remote FTP server.

This should help!

However, the Static Routes became stale (obsolete) and we were unable to delete the static routes. The routes are not in the running config (no “ip route command in config”) and a reboot wouldn’t help.

When you do

ciscoswitch# show ip route
Default gateway is 10.10.10.1

Host Gateway Last Use Total Uses Interface
192.168.1.1 10.10.10.4 0:00 460318 Vlan1
192.168.1.2 10.10.10.4 0:00 25586 Vlan1
192.168.1.3 10.10.10.4 0:00 25570 Vlan1

The static routes cannot be deleted using

ciscoswitch(config)# no ip route 192.168.1.1 255.255.255.255 10.10.10.4

or

ciscoswitch# clear ip route *

or

ciscoswitch# clear ip cache *

How to resolve?

Finally, the resolution was to disable and enable the “ip routing” service.

Disable IP Routing

ciscoswitch(config)#no ip routing

Enable IP Routing

ciscoswitch(config)#ip routing

This fixed the problem and we are back in business. The stale routing table entries are gone.

I’m sure someone out there is looking for this and might help!!!

Let’s say we have VLAN 10 which hosts the subnet 192.168.10.0 subnet, VLAN hosts 192.168.20.0 subnet and VLAN 30 hosts 192.168.30.0 subnet. For Inter-VLAN routing to work, we need to have a VLAN interface setup for each of these VLANs and configured with an IP address from the same subnet which will be the default Gateway for that subnet. Lets say, 192.168.10.254,192.168.20.254.192.168.30.254 are the IP addresses for VLAN Interfaces of VLAn 10,20,30 respectively.

Assuming the VLANs are configured already, let’s proceed to get the VLAN interfaces created.

Enable Routing on the Switch

ciscoswitch# conf t
ciscoswitch(config)# ip routing

Add VLAN Interface

ciscoswitch(config)# interface vlan10
ciscoswitch(config-if)# no shut
ciscoswitch(config-if)# ip address 192.168.10.0 255.255.255.0

This configures a VLAN interface for VLAN 10.

Default Route on Switch

Add a default route on the Switch. This will forward all traffic from the different VLANs to the default router.

ciscoswitch(config)#ip route 0.0.0.0 0.0.0.0 192.168.100.1

Interface to the Router

If the switch cannot reach the default router through a VLAN then an interface that connects to the router which does these routing needs to configured as a routed interface and assigned with an IP address that is in the same subnet as that of the Default router.

ciscoswitch(config)# interface gi0/1
ciscoswitch(config-if)# no shut
ciscoswitch(config-if)# no switchport
ciscoswitch(config-if)# ip address 192.168.100.2 255.255.255.0

This makes the interface as a routed interface and assigns an IP address in the same subnet as the default router.

Cisco Routers and Switches with L3 routing functions are seen to have problems with High CPU usage when SNMP is enabled. This can range anything from 15% to 40%. According to Cisco, these are low priority processes and other priority processes requiring CPU cycles are given priority over these processes and this level of CPU utilisation can be is normal. However, it is always better to be safe than sorry and get the CPU utilisation caused by SNMP to bare minimum so as to ensure the Routers function smoothly.

The reason behind the High CPU usage can be caused by the Network Management Server (SNMP Server) like HP Openview querying for the Routing Tables and ARP tables to learn about other networks  or querying for certain MIBs which can be resource intensive.

We can use the SNMP View configurations to include/exclude SNMP MIBs in Cisco IOS. So modify your SNMP configuration as follows:

Include the SNMP Root (ISO)

ciscorouter(config)# snmp-server view cutdown iso included

Exlcude queries for Routing Table & ARP Table

We exclude the ipRouteTable & ipNetToMediaTable MIBs to avoid polliong for Routing tables and ARP tables.

ciscorouter(config)# snmp-server view cutdown 1.3.6.1.2.1.4.21 excluded
ciscorouter(config)# snmp-server view cutdown 1.3.6.1.2.1.4.22 excluded
ciscorouter(config)# snmp-server view cutdown 1.3.6.1.2.1.3 excluded

Exclude CPU Intensive snmpUsmMIB, snmpVacmMIB,snmpCommunityMIB

These are good to disable for Security reasons as well.

ciscorouter(config)# snmp-server view cutdown 1.3.6.1.6.3.15 excluded
ciscorouter(config)# snmp-server view cutdown 1.3.6.1.6.3.16 excluded
ciscorouter(config)# snmp-server view cutdown 1.3.6.1.6.3.18 excluded

Configure SNMP Community

Configure the SNMP community with the cutdown view as follows:

ciscorouter(config)# snmp-server community public view cutdown RO
ciscorouter(config)# snmp-server community myprivate view cutdown RW

This should help. For simple SNMP configurations, click here

For official Cisco Documentation click here

Back from the holidays only to find my Windows Profile gone missing at work. One of the annoying things was to add all my remote hosts back onto WyseTerm. While the bad news is that there is no single file (which one would expect) that maintains this list, the good news comes in the form of Windows Registry. Yes, the WyseTerm host information is stored in Windows Registry and can be exported from the registry on to a new profile or other users profile.

The WyseTerm Host information, also known as the Common Address Book can be exported from the Windows Registry and then imported onto the new users profile as follows:

1. Click Start – Run – type "regedit" and press enter to open Windows Registry.

2. Navigate to

[HKEY_CURRENT_USER\Software\Hummingbird\Connectivity\[version]\HostExplorer\Common]

where [version] is the version of your Hummingbird software.

3. Click File and select EXPORT to export the "Common Address Book". Enter a file name to save the reg file.

4. Now, login as the new user and run this reg file. This should import the WyseTerm host list onto the users WyseTerm.

 This should help!!!