Tag archive: BGP

Access lists, prefix lists work very well in case we want to filter prefixes, but sometimes you may want to take action not against particular networks, but particular Autonomous Systems. Then AS-PATH filtering is comming forward.

Thanks to MED attribute we have influence on how adjacent eBGP router should get into our AS.It is especially helpful if we have 2 or more eBGP entrance into our AS.  Now, we will check how a single eBGP router that  receives MED attribute for the same prefix from many eBGP speakers and different AS…

In this lab from the scratch we will implement fully working MPLS core with Layer 3 VPN and MP-BGP vpnv4 on the provider edge routers. Also we will achieve full connectivity between customers edge routers with routing protocols. At the end we will find out how to implement “extranets” and “shared services”, thanks to which…

In this artcile we will focus on fundamental and crucial features of BGP neighborhood establishing and routes injecting into BGP processes, we also break BGP table down  for better understanding.

Each protocol has to calculate somehow the metric  in order to choose the best route. So we have the cost in OSPF, K-values in EIGRP, BGP doesn’t differ from them and also calculate the best route, but the metric of BGP is much more complicated.

We may come across on interesting issue if we get the same prefix from external BGP AS and directly via OSPF process. It may happen if we want to have another link to the destination but not neccesarily via another eBGP link. The problem that we will definetely come across on is just  another variation…

The ‘BGP community’ is an additional information (attribute) adding to prefixes, that is being advertised to the BGP neighbors. Based on this information a BGP neighbor can make a decision what else to do with received prefix. For example we may mainpulate attributes, filter routes, etc.

You may be familiar very well with BGP protocol but probably until you don’t start use MPLS L3 VPN or IPv6 you will not have awareness that the other kind of BGP addresses exist. For carrying the other BGP addresses responsible is Multi Protocol BGP,  that we  break down right now.

Border Gateway Protocol has two features which enable improving scalability. Thanks to them BGP AS domain with a lots of routers will be working more efficient and seamlessly. They are similar to each other and because of that, they are very often confused. But first, in order to understand RR and Confederations we have to…

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