Skip to main content

Bidirectional Forwarding Detection (BFD)

 Bidirectional Forwarding Detection (BFD)

BFD provides a rapid failure detection mechanism for routing protocols like BGP, EIGRP, IS-IS, and OSPF. It is more efficient and quicker than traditional reduced timer methods, detecting failures in less than one second.

  • BFD Use Cases:
    • Works independently of the media, encapsulation, or topology.
    • Detects failures in the forwarding path, including interfaces, data links, and forwarding planes.
    • Not limited to routing protocols—also used for HSRP, static routes, and other protocols.
  • Advantages of BFD:
    • Detects failures faster than reduced routing protocol timers.
    • Is lightweight, using the data plane for failure detection, making it less CPU-intensive than timer-based detection methods.
    • Can be applied consistently across multiple protocols.
  • BFD Configuration for Various Protocols:

For BGP:

router bgp 100

 neighbor 172.16.10.2 fall-over bfd

For EIGRP:

router eigrp 1

 bfd all-interfaces

For OSPF:

router ospf 1

 bfd all-interfaces [strict-mode]

For HSRP:

interface GigabitEthernet0/1

 standby bfd

  • Technical Tip: BFD can be configured in strict-mode for OSPF, which ensures that the OSPF session is only established after a BFD session is established.

 

Labels:

Comments

Post a Comment

Popular posts from this blog

How to import Putty Saved Connections to mRemoteNG

Just started using mRemoteNG and its being very cool to connect to different remote connection with different protocols e.g Window Remote Desktop, VNC to Linux, SSH, HTTP connection etc. from a single application. As new user I configured some remote desktop connection which was quite easy to figure out. But when I wanted to add SSH connections, it came in my mind to import all of the saved connections in the putty. But I couldn't figure it out how can it be done, though it was quite easy and here are the steps. Open your mRemoteNG Create a folder if you want segregation of multiple networks Create a new connection Enter the IP address of remote server under connection in Config pane Under the config pane, select protocol " SSH version 2 ".  Once you select protocol to SSH version 2 you are given option to import putty sessions, as shown in the snap below. In the above snap, I have imported CSR-AWS session from my saved sessions in Putty.
1 comment
Read more

AS Path Prepending: Controlling Inbound Traffic in BGP

AS Path Prepending is a BGP feature used to make a specific path appear less preferred by artificially lengthening the AS path. This is done by adding your AS number multiple times to the AS path. It is a common method to influence inbound traffic from external networks. Longer AS Path = Less preferred route . Example Scenario : You have two ISPs: ISP1 (through CE1) and ISP2 (through CE2). You want inbound traffic from the internet to prefer ISP1 over ISP2. Network Topology : CE1 (connected to ISP1): 10.0.1.1/30 CE2 (connected to ISP2): 10.0.2.1/30 iBGP Router (Internal) connected to both CE1 (10.0.1.2/30) and CE2 (10.0.2.2/30). Configuration on CE2 (AS Path Prepending to Make ISP2 Less Preferred) : Create a route map to prepend your AS path multiple times for CE2: route-map PREPEND_AS permit 10 set as-path prepend 65001 65001 65001 Apply this route map to the neighbor in the BGP configuration for CE2: router bgp 65001 neighbor 10.0.2.1 remote-as 65002 neighbor 10.0.2.1 ro...
Post a Comment
Read more

Authoritative DNS Servers Delegation and Internal DNS Explained

DNS (Domain Name System) plays a critical role in how users and systems find resources on the internet or within internal networks. Whether it's managing an internal domain in an enterprise or delegating parts of a domain for traffic distribution, DNS setups vary widely depending on needs. In this blog post, we’ll break down the different types of DNS setups, including authoritative DNS servers, DNS delegation, and how internal DNS functions within organizations. 1. Authoritative DNS Server An Authoritative DNS server is the final source of truth for a specific domain. When someone queries a domain (e.g., example.com ), the authoritative DNS server for that domain holds the DNS records (A records, CNAME, MX, etc.) and responds with the corresponding IP address. Key Points: Who can host it? Authoritative DNS servers are often hosted by domain registrars (e.g., GoDaddy, Namecheap) or cloud DNS providers (e.g., AWS Route 53, Cloudflare). However, organizations can also host their ...
Post a Comment
Read more