Jul 2, 2014

BGP Routing Issues Case Study 2 - Unreachable to the learned BGP route

If you have only one BGP router with multi-home ISP uplinks, its much easier to maintain the BGP routing table because it was totally under centralized control.

But as network continue to expand and we start to consider the redundancy issue, then your network will add additional multiple BGP speakers and you must enable IBGP between these BGP routers.

Jun 23, 2014

BGP Routing Issues Case Study 1 - BGP configuration without filter

I learned BGP since 1998, of course, just like many other people, I made some human errors without fully understanding of BGP protocols. Just copy and paste sample configuration from cisco websites and modified it then applied to the production BGP router. However, its a dangerous thing if you just know part of something without complete knowledge and implement it on the production network.

This is the reason I want to start to share my knowledge and experience about BGP protocol. Maybe it can help some people to prevent doing some ridiculous BGP incidents over internet(ex: advertise private IP or default route to the internet)

May 30, 2014

[POC] Cisco vs Juniper running OSPF w/o Backbone Area 0

As everyone knows that OSPFv2 is a standard routing protocol (http://www.ietf.org/rfc/rfc2328.txt), but not all vendors device will implement it exactly the same. Especially when the network scenario was not follow the standard design, then it might have different exceptional behavior in different vendor devices.

In order to compare the difference behavior between Cisco and Juniper. I designed a special OSPF topology just like below, so we can see Cisco and Juniper have different result of routing exchange behavior.

May 24, 2014

Learning JUNOS from IOS - Day3 (View/Modify Configuration)

A bird in the hand is worth two in the bush

Day 3 - How to view or modify JUNOS configuration ?

Entering Configuration Mode

When you stand behind an engineer, you can identify the engineer is Cisco or Juniper guy easily. 

Most cisco engineers like to use the command 'conf t' to enter configure mode of router or switch.

router> enable
router# conf t
Enter configuration commands, one per line.  End with CNTL/Z.

When you want to show any results, you don't need to exit to the privilege mode(#) to show it. You can leverage 'do' command to check the status.

router(config)# do sh ip int brief
Interface              IP-Address      OK? Method Status                Protocol
GigabitEthernet1    YES manual up                    up      
GigabitEthernet2       unassigned      YES unset  administratively down down    
GigabitEthernet0       unassigned      YES manual up                    up      
Loopback0             YES manual up                    up     

Mar 28, 2014

[POC] Junos script Operations Automation (op script) - show-bgp-policy

Junos Script Automation is a powerful and flexible on-box toolset which provides customization of network behavior, adaption to what your application expects to configure, manage and diagnose if and when needed. It sits right above the Junos OS, with a northbound interface to Junos Space applications, and southbound access to Junos SDK applications and native management plane instrumentation. This customized programmable solution makes your application smarter and better in real-time.

In Juniper official website provides many script samples to match part of common requests. In my company, we deployed many inter-connections EBGP/IBGP between router or layer 3 switch. So I picked one op script from the JUNOS Script Library - show bgp policy: display all routing-policies in sequential order for a selected BGP peer.