BGP4 Case Studies/Tutorial Sam Halabi-cisco SystemsThe purpose of IntroductionThe Border Gateway Protocol (BGP), defined in RFC. On-line BGP Resources and Information Routing Recommendations · Connect’s FAQ on multihoming and BGP · BGP4 Case Studies/Tutorials by Sam Halabi. BGP4 Case Studies/Tutorial. Sam Halabi-cisco Systems. The purpose of this paper is to introduce the reader to the latest in BGP4 terminology and design issues.

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BGP4 Case Studies/Tutorial – PDF

If we finish the list without a match then the route we are looking gbp will not be accepted nor forwarded. Gateway of last resort is It’s very important, however. This is a workaround in order to achieve load balancing between two EBGP speakers over parallel serial lines. Explain the operation of the More information. Local router configuration, software, hardware WAN media physical failure, More information. InterAS or Interdomain routing protocol for exchanging network reachability information.

For example, if I define two instances of the route map, let us call it MYMAP, the first instance will have a sequence-number of 10, and the second will have a sequence number of Feasible Distance FD Example: It includes information on the benefits of the new feature, supported platforms.

In the case of EBGP, most of the time the peer routers are directly connected and loopback does not apply. Sak remember that these routes are generated in studiss to other BGP routes that BGP has learned zam neighbors internal or external. If RTA wants to redistribute to RTB routes about with a metric of 2 and all other routes with a metric of 5 then we might use the following configuration: BGP passes on information that it learns from one peer to other peers.


Exterior routing protocols created to: This feature was introduced.

BGP4 Case Studies/Tutorial

This feature is configured for links between directly. So if I get the packet and there is a more specific match than which exists of course the router will send it to the specific match otherwise it will disregard it.

The prefix the network itself The prefix-length the length of the. One restriction on route maps is that when used for filtering BGP updates as we will see later rather than when redistributing between protocols, you can NOT filter on the inbound when using a match on the ip address.

BGP4 Case Studies/Tutorial Index

An important point to remember is that BGP will not accept updates that have originated from its own AS. Multiple instances of the same route map same name-tag can be defined. Scenario International Travel Studis More information. If the match criteria are met and we have a deny then the route will not be redistributed or controlled and we break out of the list. RTA will have two choices to reach next hop: Snoeren HW 3 due Wednesday! This sounds scary because now you are dumping all of your internal routes into BGP, some of these routes might have been learned via BGP and you do not need to send them out again.

The difference is that routes generated by the network command, or redistribution or static, will indicate your AS as the origin for these networks.


The feature is enabled by default when a supporting Cisco software image is installed. The Internet is a collection. This feature is configured for. Border Gateway Protocol” Lecture The conditions that we talked about are defined by the stkdies and set configuration commands. BGP will always propagate the best path to its neighbors. It’s very important, however, More information. Filtering on the outbound is OK. RTC router eigrp 10 network redistribute bgp default-metric router bgp neighbor remote-as neighbor distribute-list 1 out halbi eigrp 10 access-list 1 permit The access-list is used to control what networks are to be originated from AS In the above example the same could have been accomplished by doing: On the other hand, RTB is indicating a neighbor that is directly connected and that is why it does not need the ebgp-multihop command.

Routing in Small Networks. This feature is configured for More information. Static routes it could be some IGP also are used to introduce two equal cost paths to reach the destination.

This is indicated with an i in the BGP table.

Note that we need the static route to get the router to generate because the static route will put a matching entry in the routing table. By introducing loopback interfaces, the next hop for EBGP will be the loopback interface.