Cisco BGP Route Server - Concept and Configuration

[Music] cisco bgp root server in this video i want to explain the benefit and reason for root server usage in the service provider world you will also learn about the configuration procedure and we will have a demonstration about it before talking about the function of the root server i want to explain what is internet exchange and how ix works an ix is a physical location that provides infrastructure for the service providers to exchange internet traffic between their networks the infrastructure includes rackspace electricity cooling resources and common switching infrastructure for service providers to directly connect their network ix is a cost-saving option for smaller service providers who do not have resources to maintain multiple one-to-one connections in our topology you can see the shared public peering at ix notice that in the physical topology shown in the diagram all the service providers share a common subnet across the same switching infrastructure the full mesh peering of a service provider present to scaling and administrative challenge all the ebgp sessions are formed across a single link and a flap on one link causes a bgp session to flap on multiple sp networks which can lead to service impacts also there is a huge operational overhead from the contracts that are negotiated between the service providers for each peering root servers solve this problem by providing rr functionality for ebgp sessions root servers facilitate multilateral peering instead of maintaining multiple ebgp sessions a provider only peers with the root server that takes care of reflecting the routes.why oh you can see the difference in the new logical topology now let's jump into the configuration and deployment section first step in our root server deployment is to establish session between ix router and other routers let's do the configuration do step one configure ix router as a neighbor with as500 and i will repeat the same procedure for each router [Music] now it's time to configure ix as a root server to make a des root server we have two stages stage one configure all s routers as neighbors stage two configure neighbors as router server client for stage two we need to go under address family and do the root server client configuration now the neighbourship is done we go under address family and issue the root server client command for each isp router [Music] the configuration is done now we should add as65000 and as65001 to our diagram and advertise some network [Music] [Music] i will advertise 192-168-40-24 from as65001 side and advertise 192-168-10-24 from as65000 side [Music] [Music] the bgp root server provides a s path med and next hop transparency the peering is actually transparent outside the ix even though the service providers may be directly connected at the ix but before we check the transparency we will face an issue as you can see we will receive an error message on isp routers the isp drops updates messages marking them as malformed the reason for this issue is router server transparency we know the root server has transparency on as path this causes a root server not to put its own as in the as path list on the other hand bgp by default denies any updates received from an ebgp peer that does not list its own aes number at the beginning of the as path list this rule will cause the issue to receive updates from the root server the root server clients should disable this behavior let's do the configuration on isp routers and see the result [Music] [Music] now we receive the routes and updates from r1 and r4 and lastly because of as path transparency we do not see as500 although the isp routers receive all the updates from ix router so that was a lesson about root server function i hope you enjoyed the video for more cool topics please visit my website on www.networkingwithsan.com or join my youtube channel stay safe and see you soon again

Channel: Networking with Ehsan

Views: 2,483

Keywords: cisco, bgp, cisco bgp, bgp route server, bgp ix, cisco route server, cisco bgp route server, cisco bgp roure-server, bgp configuration, bgp training, cisco bgp training

Id: yQQhxy23GAc

Length: 10min 10sec (610 seconds)

Published: Fri Aug 07 2020