No space left on device /tmp

Three days ago, nagios server stopped working and all servers cannot be monitor. The syslog says nagios is "Unable to create temp file for writing status data!". It looks like the disk is full. So i run the command df -h:

shiop:/var/log# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1              28G  1.9G   25G   8% /
tmpfs                 252M     0  252M   0% /lib/init/rw
udev                   10M  608K  9.5M   6% /dev
tmpfs                 252M     0  252M   0% /dev/shm
/dev/sda3              43G  2.7G   38G   7% /home

Part 4: Frame Relay Cloud

Berhubung gue lagi males bikin tulisan dalam bahasa inggris, kali ini gue buat dalam bahasa indonesia aja lah, dengan gaya bahasa yang tidak terlalu formal tentunya agar mudah "dicerna" dan tidak kaku. To the point aja, setelah baca tutorial, ebook dan googling sana-sini, gue mau bikin sedikit ringkasan mengenai cloud Frame Relay. Pada umumnya, ketika customer menghubungkan router-router yang ada di kantor cabang dan pusat melalui cloud Frame Relay milik ISP. Mereka tidak tahu apa yang ada di dalam cloud tersebut, cloud Frame Relay akan nampak transparan dari sisi mereka.  Kira-kira seperti inilah topologi Frame Relay yang nampak dari sisi customer.

Topologi Logic Frame Relay Cloud

Setelah melihat topologi logic di atas, mari kita lihat topologi fisik-nya seperti gambar di bawah ini:

Topologi Fisik Frame Relay Cloud

Dari topologi fisik di atas, cloud Frame Relay terdiri atas empat buah switch , yaitu FR1, FR2, FR3 dan FR4. Tidak ada serial line antara FR2 dan FR4, Jadi kita akan gunakan tunneling untuk melewatkan frame Frame Relay dari FR2 ke FR4. Berikut konfigurasi masing-masing switch Frame Relay di atas:

FR1:

 !  
 hostname FR1  
 !  
 frame-relay switching  
 !  
 interface Serial1/0  
  description to R1  
  no ip address  
  encapsulation frame-relay  
  serial restart-delay 0  
  frame-relay intf-type dce  
  frame-relay route 102 interface Serial1/1 112  
  frame-relay route 103 interface Serial1/1 113  
 !  
 interface Serial1/1  
  description to FR2  
  no ip address  
  encapsulation frame-relay  
  serial restart-delay 0  
  frame-relay intf-type nni  
  frame-relay route 112 interface Serial1/0 102  
  frame-relay route 113 interface Serial1/0 103  
 !  

Part 3: Frame Relay Switching

A Router, by default is DTE devices, it can be configured as a Frame Relay Switch by changing the interface to a DCE. Frame Relay Switch will forward Frame Relay frames based on upon their DLCI numbers. Let's see the Logical Frame Relay network below.

Logical Frame Relay Network

Frame Relay Cloud can be one or a group of Frame Relay switch or a router configured as Frame Relay switch. On the network topology below, we'll see the router functioned as Frame Relay switch.

Part 2: Frame Relay Point-to-Point and Multipoint

Now, i'll make some notes about the issues in Frame Relay. When we connect multiple sites through a single router interface, we'll face the routing problem caused by split horizon. Split horizon is a mechanism in routing protocol that designed to eliminate routing loop by blocking routing updates to be sent out of the router interface. See the picture below:

Split Horizon in Frame Relay

R1 received routing updates through serial S0 from R4, but it won't be sent out to R2 or R3 because of split horizon. And how to resolved this problem? Use subinterface. There are two type of subinterfaces support by Cisco:

• Point-to-point, used when we have a separate subnet for each VC. Only one DLCI can be configured per point-to-point subinterfaced. Here's the example of the point-to-point configuration:

     interface Serial1/0

      encapsulation frame-relay

      serial restart-delay 0

    !

    interface Serial1/0.102 point-to-point

      ip address 10.1.1.1 255.255.255.252

      frame-relay interface-dlci 102

    !

• Multipoint, by default, on cisco router, the physical interfaces are the multipoint interfaces. When we created a multipoint subinterfaces under the physical interfaces, we need to specifically assign DLCI to multipoint subinterfaces. Here's the example of the point-to-point configuration:

     interface Serial1/0

      encapsulation frame-relay

      serial restart-delay 0

    !

    interface Serial1/0.103 multipoint

     ip address 10.1.2.1 255.255.255.248

     frame-relay interface-dlci 103

     frame-relay interface-dlci 104

    !

Labs: MPLS using EIGRP between PE-CE

Labs Summary :

1. MPLS backbone using IS-IS as IGP
2. PE-CE using EIGRP routing protocol
3. MP-iBGP runs on PE1 and PE2 and using ASN 65000

Part 1: Frame Relay Basic

Frame Relay is WAN technology that works on layer 2 (Data Link) of the ISO technology. Frame Relay initially propose at Consultative Committee on International Telephone and Telegraph(CCITT) in 1984. In 1990, Cisco, DEC, Nortel and Stratacom formed a consorsium to develop frame relay technology . 

Frame relay devices are consist of:

1. DTE(Data Terminal Equipment), located on the customer devices, such as router, bridges,etc).
2. DCE(Data Circuit-Terminating Equipment), located on Frame Relay  PSN (Packet Switched Network)

Frame Relay create virtual circuit to form end-to-end links and uniquely identified by a data link connection identifier (DLCI). DLCI is a value assigned by Frame Relay service provider and is locally significant, which means its values is unique in the LAN, but not in the WAN. Frame Relay virtual circuit fall into two categoris:

1. SVC (Switched Virtual Circuit), connection between DTE devices will be established if there's data to be transferred. If no data is transferred, the connection will be in idle state for a defined period and then terminated.
2. PVC (Permanent Virtual Circuit), connection between DTE devices will be established permanently.  

DLCI Mapping

Remember, Frame Relay only works on layer 2 of the OSI model and it doesn't understand IP addressing. So we need to map IP address to a DLCI number on Frame Relay switch. Mapping can be done statically or dynamically by administrator on the router.

Export Data From MySQL Database to CSV Files

First  of all, thanks to the developer of MySQL who created mysqldump tools. By using this tool, you may be able to export data from MySQL databases to CSV files and deliminated text files. Here is the syntax:

 mysqldump -u[username] -p[password] -t -T/path/to/directory [database] --fields-terminated-by=,  

A destination path in the command above should be writeable for user mysql. You can use "--fields-terminated-by=" to change deliminated flag like comma, tab, etc. Consider that you have a database with its table like this:

 mysql> use trial;  
 Reading table information for completion of table and column names  
 You can turn off this feature to get a quicker startup with -A  
 Database changed  
 mysql> select * from moneter;  
 +----+--------+---------+  
 | id | mphone | dshell |  
 +----+--------+---------+  
 | 1 | BBBOH | P808091 |  
 | 2 | BBBIJ | P909091 |  
 | 3 | AABCO | P606052 |  
 | 4 | ABBCO | P608752 |  
 | 5 | AGHCO | P788752 |  
 | 6 | GGOUG | P102220 |  
 | 7 | GGOJG | P102343 |  
 +----+--------+---------+  
 7 rows in set (0.00 sec)