- One of the fundamental pillars holding up the internet and Global economy with ductape and hope :)
- The internet is madeup of collection of networks that work like their own autonomos system (ISP, Big corporates, Government has their own network)
- BGP allows them to announce to things that the network exists and which network can be reached by them. (Protocol used by routers)
- Routing protocol of the internet.
- Slowest Routing Protocol in the world
- Individual IPs are grouped together into prefixes and routing tables between the autonomos systems are maintained by bgp
- Application layer TCP port 179
- Neighbours are manually defined.
- TCP is used for reransmitting the lost data o avoid duplicate data.
Advantages:
- Efficient Routing
- Connectivity
- Scalability
- Traffic Control
Disadvantages:
- It does not check for the authority to change traffic path by remote network
- It does not check authenticity
- It does not check for policy violation
- Management of trust and untrust
- Config is complex
- It takes time to add or remove a network from bgp routing table
- Triggered updates only!!!
Runs on "Trust me Bro vibes"
Autonomous System (AS)
- It's a network or a collection of network that are managed by a single organization or administrative entry.
BGP Message Types:
Open:
It is used to initiate a BGP session between 2 routers. Includes the below:
- BGP version
- Sender AS number
- Hold Time (Cisco default 180 seconds)
- BGP identifier
- optional parameter
Keepalive Message:
- This Message is used to maintain the BGP session between the BGP Peers
- It will be sent once in one-third the "hold time". The default timer in cisco device is 60 seconds.
Update:
If any new route added and existing route deleted. Path Attributes
Notification:
- Terminate or rejects a BGP connection.
- Can include error message (" BGP version not supported")
Dynamic Routing Protocol:
- Interior Gateway Protocol (IGP)
- OSPF
- ISIS
- EIGRP
- RIP
- IGRP
- Exterior Gateway Protocol (EGP)
- BGP
