Allied Telesis x908, X8100 manual BGP Concepts and Terminology, BGP peers, BGP updates

Page 4

BGP: Concepts and Terminology

BGP: Concepts and Terminology

Before moving on to look at the filtering processes, it is important to first have some understanding of certain aspects of how BGP works. The following sections describe:

BGP peers

BGP updates

Update attributes

BGP peers

Definition Within the BGP protocol, the exchange of routing information is carried out between pairs of routers. Two routers create a TCP connection with each other, and exchange routing information as specific data packets within that TCP session. The routers at the ends of the TCP connection are referred to as BGP peers. Any given router can form peering relationships with multiple routers.

Usually a BGP router with an ISP will form peer relationships with BGP routers at other ISPs or clients with which it has entered into data transporting agreements.

The process of BGP filtering usually comes down to a matter of specifying the routes that will be sent to, or received from, each of a router's peers.

BGP updates

Definition Once a router has established a BGP connection with a peer, it will start to exchange routing information with that peer. A BGP update message is the packet that is used to transfer the routing information.

The routing information contained within an update message consists of:

a set of attribute values (see the next section for a description of the possible attributes)

and

a list of one or more prefixes. A prefix is the network portion of an IP address, in dotted decimal notation, optionally followed by a "/" character and a decimal number from 0 to 32. Each prefix contained within an update message represents a network that can be reached through the IP address given in the NextHop attribute contained in the same update message.

Note: There is only one NextHop attribute in an update message, so all the routes in the update message have the same next hop.

Page 4 Use Route Maps and Other Filters to Filter and Alter BGP and OSPF Routes

Page 3 Page 5
Image 4
Page 3 Page 5
Contents Introduction Technical GuideContents IntroductionWhich products and software version does it apply to? BGP Applying Route Maps to Imported RoutesRelated How To Notes Which products and software version does it apply to?BGP Concepts and Terminology BGP updatesBGP peers Update attributes OriginAS-path Next-hopAccess Control List ACL filters BGP Overview of the Available Filter TypesFilter types Distribute filtersExamples for filtering BGP Update messages Difference and Relationship in BGPHierarchy of the Different Filters BGP Example Example Distribute filters on page  Example AS path filters on page  Example Prefix filters on pageBasic configuration AlliedWare switch Confirming the neighbor relationshipawplus#show ip route BGP Configuring Distribute Filters About ACLsExample Distribute filters Using ACLs as filtersFilter out one particular route from a neighbor Filter out a range of prefix lengths 3. Check that the IP route table now includes all the routes awplusconfig# neighbor 45.45.45.46 distribute-list list2 in6. Shut down the neighbor, and then bring it up again Use a numbered ACL instead of a named ACL awplusconfig-router# do show ip route BGP Configuring AS Path Filters AS path listsExample AS path filters Using AS path lists as path filtersDiscard or allow routes from a neighbor a neighbor 4. Shut down the neighbor, and then bring it up again7. Shut down the neighbor, and then bring it up again Another example An outgoing filter that uses an AS-path listBGP Configuring AS Path Filters About prefix lists BGP Configuring Prefix FiltersMask length Using prefix lists as prefix filters Example Prefix filtersawplusconfig-router# neighbor neighbor prefix-list list-name in awplusconfig-router# neighbor neighbor prefix-list list-name outFilter out a range of different prefix lengths BGP Configuring Prefix Filters BGP Configuring Route Maps Structure of a route mapClauses Configuring a match clauseAn AS path list A community list CaseOne or more prefixes, by using a prefix list One or more prefixes, by using an ACLConfiguring a set clause A next hop addressAn origin A metric the MED attributeset community community-values additive set weight set atomic-aggregateset extcommunity rtsoo ext-comm-number set ip next-hop ipaddThe effect of different combinations of clauses One match clause with an actionNo match clause and one or more set clauses A match clause and one or more set clausesUpdate from Peer Update 1 to PeerUpdate 2 to Peer Router ASFirst, enter BGP router mode for the AS. The prompt should look like Examples Example B Match on a prefix-list that denies an entryawplusconfig#ip prefix-list test1 permit 52.0.0.0/8 awplusconfig-route-map#set metric4. Apply this route map as the in route map on the neighbor Example D Matching on a next-hop prefix-list Example E Prepending AS numbersawplusconfig-route-map#match ip address awplusconfig-route-map#router bgp1. Configure the AW peer to send out a community number The routes coming from that peer has communityadd ip routem=com entry=1 set commmun=8989 set bgp peer=45.45.45.45 outroutemap=com sendcommunity=yesBGP#show ip route set bgp peer=45.45.45.45 outroutemap=mixed sendcommunity=yes 8. Add that ACL as a distribute-list in-filter on the neighbor route-map marker permit Examples ACLs Path filters Prefix filters Route mapsBGP Applying Route Maps to Imported Routes Syntaxneighbor default-originate Other Uses of Route Mapsneighbor unsuppress-map networkRoute map configuration BGP configurationBGP Route Map Filtering Example set local-preference route-map outdef permit Metric OSPF Configuring Route Maps for Filtering and Modifying OSPF RoutesInterface A prefix, by using an ACL A prefix, by using a prefix listExternal route type OSPF Applying Route Maps  Set the metric, by using the command set metric
Related manuals
Manual 8 pages 39.31 Kb Manual 21 pages 8.63 Kb

X8100, x908 specifications

The Allied Telesis x908 and the SwitchBlade x900 series of network switches are cutting-edge solutions designed to address the demands of modern networking environments. These switches are known for their high performance, reliability, and robust feature sets, making them ideal for enterprise and service provider networks.

The Allied Telesis x908 series consists of modular and chassis-based systems that can accommodate a variety of network configurations. One of the main features of the x908 series is its ability to offer high scalability with support for a large number of ports. This makes it suitable for data centers and large enterprise networks where space and bandwidth optimization are critical.

In addition to scalability, the x908 series supports advanced Layer 2 and Layer 3 switching capabilities. This allows for efficient traffic management and routing, ensuring that data is delivered swiftly and reliably. The x908 also incorporates intelligent features such as Quality of Service (QoS), which prioritizes critical network traffic, ensuring that time-sensitive data—like voice and video—maintains its quality during transmission.

The SwitchBlade x900 series takes this functionality further with its innovative modular architecture. This allows organizations to configure their networks to meet specific needs by choosing from a variety of interface cards and service modules. The SwitchBlade x900 also supports advanced security features such as Access Control Lists (ACLs) and VLAN segmentation, which provide enhanced protection against unauthorized access and network threats.

Another hallmark of the x908 and SwitchBlade series is their support for high-speed Ethernet technologies, including 10G and 40G Ethernet. This enables organizations to keep pace with the increasing bandwidth demands of applications and services, particularly in cloud computing and data-intensive workloads.

Both the x908 and the SwitchBlade x900 series are designed with energy efficiency in mind, featuring power-saving technologies that reduce overall operational costs. Coupled with Allied Telesis' management tools, which provide detailed analytics and monitoring, network administrators can optimize performance and energy consumption simultaneously.

In summary, the Allied Telesis x908 and SwitchBlade x900 series offer a comprehensive suite of features, high performance, scalability, and advanced networking technologies. They represent a strategic investment for organizations looking to build resilient, efficient, and future-proof network infrastructures.
Top Page Image Contents