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)  

Memblokir Iklan dengan Adblock Plus di Google Chrome

Tanpa banyak basa-basi, langsung saja install extension Adblock Plus untuk Google Chrome via Chrome Webstore. Extension ini berguna untuk memblokir iklan-iklan yang muncul di halaman website (biasanya di website-website berita, seperti detik.com, kompas.com, dll). 

Adblock Plus di Webstore

Berikut contoh halaman web beriklan yang dibuka menggunakan browser Chrome sebelum dan sesudah menginstall extension Adblock Plus

BGP Attribute: Weight, Local Preference and Metric

Atribut BGP, seperti weight, local preference dan metric akan sangat berguna ketika router Anda memiliki multiple exit/outgoing atau melakukan manipulasi outbond routing. Atribut ini akan membantu Anda dalam menentukan best path sesuai keinginan Anda.

Weight

Router dengan weight tertinggi akan dipilih sebagai best path. Nilai weight antara 0 sampai 65535. Weight hanya berlaku di lokal router saja.

Format perintah:

 neighbor {ip address | peer-group} weight {value}  

Berikut contoh konfigurasi bgp weight:

 inter-core(config)# router bgp 500   
 inter-core(config-router)# neighbor 1.2.4.5 remote-as 100   
 inter-core(config-router)# neighbor 1.2.4.5 weight 200   

Posted from Mobile Android

Yeahhh....this post is sent from android mobile.

Tips & Tricks: Create Directory Without Name In Unix

Oneday, someone just hack my server, and then he downloads some C codes(exploit) from internet, compile it and run it. Oh my gosh! my server become freeze & the load is very high. It took all the resources on my server. By using command "ps axuf", i can see where this exploit running from. But, it's strange to see the path of this exploit.

 root@dns:# pwd  
 / /ex/exploit  
 root@dns:# cd /  
 root@dns:# ls  
    boot etc  initrd.img   lib     media opt  root selinux sys usr vmlinuz   webmin-setup.out  
 bin dev  home initrd.img.old lost+found mnt  proc sbin srv   tmp var vmlinuz.old xen  

Tips & Tricks: Disable Prompt "more" on Cisco

If we execute or run a command (eg: show running or show interfaces) on cisco console, we'll see a prompt "--more--" at the bottom if the output command exceed the length of the screen.  You can disable it by configuring terminal length like this:

1:  line con 0  
2:   length 0  
3:  line vty 0 4  
4:   length 0  

BGP Confederation

BGP confederation divide an AS into sub AS running eBGP on every router, or we can say that it is a group of router running eBGP, but known as a single AS from outside. BGP confederation can reduce the iBGP mesh inside an AS, besides BGP route reflector. BGP confederation is more complex than route reflector, since we have to configure for every router inside a confederation. 

Here is our topology. We use 4 router running BGP, consist of 3 router within a confederation and 1 router from outside. Router R4 will recognize ASN R3 as 100, not 65003. To activate BGP confederation on cisco router, use the following command:

1:  bgp confederation identifier <asn>   
2:  bgp confederation peers <sub-asn 1> <sub-asn 2> <sub-asn ...>  

bgp confederation identifier refer to confederation's ASN, in this topology, our confederation's ASN is 100. And bgp confederation peers refer to sub ASN for all peers router.

BGP Route Reflector

BGP has a loop prevention mechanism to prevent routing loop in the network, but there is different implementation this mechanism in eBGP and iBGP. eBGP using AS path attribute to do loop prevention. while iBGP using split horizon mechanism(in iBGP, all of routers will use the same AS, so it can't use AS path to prevent routing). By using split horizon mechanism, a route received from iBGP neighbor won't be advertised to any other iBGP neighbor. So we need a full-mesh network in iBGP.

Writing or not writing

Someone has told me why make a writing on your blog. Does anyone read that? Well, i don't care whether  anyone will read my writing or not, i just care about my writing skill :). So let's begin writing.

Simple OSPFv3 on Cisco Router

OSPFv3 is designed to use in IPv6 protocol. It has the same fundamental mechanisme just like OSPFv2 on IPv4. In this article, we will configure simple OSPFv3 using 2 cisco router.  Note that, before we enable OSPFv3 on cisco router, we need  to enable IPv6 unicast-routing and  enable IPv6 on the interface.  

Here is the configs of our router:

Instalasi Xen di Debian

Xen merupakan salah satu teknologi virtualisasi berbasis opensource, yang memungkinkan beberapa sistem operasi berjalan dalam hardware komputer yang sama secara konkuren.

Instalasi Xen

Install paket-paket Xen dari repositori:
root@local# apt-get install xen-tools xen-linux-system-2.6.32-5-xen-686 xen-utils-4.0 xenstore-utils xen-hypervisor-4.0-i386

Setup DKIM (DomainKeys Identified Mail)

DKIM (DomainKeys Identified Mail) adalah salah satu metode untuk email authentifikasi yang mengijinkan penerima email untuk melakukan verifikasi bahwa pesan/email yang di terima datang dari domain dan server yang benar dengan melakukan pengecekan alamat email pengirim dan isi pesan secara terintegritas. DKIM dikembangkan berdasarkan teknik DomainKeys milik Yahoo. DKIM akan sangat berguna jika traffic outgoing email banyak yang menuju ke layanan email Yahoo atau Gmail, tanpa DKIM, mungkin saja email yang kita kirim akan dikategorikan sebagai junk mail atau spam oleh mereka.