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BGP & BGP4+ (Border Gateway Protocol IPv4 & IPv6)
Software Reference Supplement for x-Series Switches
AlliedWare Plus™ Operating System
Version 5.4.3-2.6
SwitchBlade® x8112
SwitchBlade® x908
x900-24XS and x900-24XT
x900-12XT/S
x610-24Ts and x610-24Ts/X
x610-48Ts and x610-48Ts/X
x610-24Ts-PoE+ and x610-24Ts/X-PoE+
x610-48Ts-PoE+ and x610-48Ts/X-PoE+
x610-24SPs/X
C613-50032-01 REV D
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Acknowledgments This product includes software developed by the University of California, Berkeley and its contributors. Copyright ©1982, 1986, 1990, 1991, 1993 The Regents of the University of California. All rights reserved. This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.openssl.org/). Copyright ©1998-2008 The OpenSSL Project. All rights reserved. This product includes software licensed under the GNU General Public License ava
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Table of Contents Chapter 1 BGP and BGP4+ Introduction Introduction...................................................................................................................................................................... 1.3 BGP and BGP4+ ASNs and AS_Path Attributes............................................................................................. 1.4 Internal and External BGP Concepts........................................................................................
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BGP Optimization .........................................................................................................................................................1.35 How to determine Backdoor Routes ..............................................................................................................1.35 How to set the BGP Administrative Distance .............................................................................................. 1.35 How to change BGP default local pr
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bgp deterministic-med (BGP and BGP4+) ..........................................................................................................3.29 bgp enforce-first-as (BGP and BGP4+)..................................................................................................................3.30 bgp fast-external-failover (BGP and BGP4+) ......................................................................................................3.31 bgp graceful-restart (BGP and BGP4+)..........
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neighbor disallow-infinite-holdtime (BGP and BGP4+) .............................................................................. 3.112 neighbor distribute-list (BGP and BGP4+)........................................................................................................ 3.114 neighbor dont-capability-negotiate (BGP and BGP4+)............................................................................... 3.117 neighbor ebgp-multihop (BGP and BGP4+)......................................
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show bgp memory maxallocation (BGP).......................................................................................................... 3.218 show debugging bgp (BGP).................................................................................................................................. 3.219 show ip bgp (BGP) .................................................................................................................................................... 3.220 show ip bgp attrib
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Software Reference Supplement for SwitchBlade® x8112, x908, x900 and x610 Series Switches TM i.viii AlliedWare Plus Operating System - Software Version 5.4.3-2.6 C613-50032-01 REV D
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Chapter 1: BGP and BGP4+ Introduction Introduction ...........................................................................................................................................1.3 BGP and BGP4+ ASNs and AS_Path Attributes ..................................................................1.4 Internal and External BGP Concepts .............................................................................................1.5 Public and Private ASNs.......................................
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BGP and BGP4+ Introduction How to set the BGP Administrative Distance .................................................................. 1.35 How to change BGP default local preference value...................................................... 1.35 How to redistribute the default network 0.0.0.0 ............................................................ 1.36 How to adjust BGP Timers ...................................................................................................... 1.36 How
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BGP and BGP4+ Introduction Introduction This chapter introduces terminology and concepts about BGP for IPv4 and BGP4+ for IPv6, including the concepts of autonomous system numbers (ASN), path attributes (PA), and both internal and external BGP and BGP4+. For basic BGP and BGP4+ configuration examples, see Chapter 2, BGP and BGP4+ Configuration. For details about the commands used in these examples, or the outputs from validation commands, see Chapter 3, BGP and BGP4+ Commands. This chapter p
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BGP and BGP4+ Introduction BGP does not send any more route updates than it absolutely has to. When routers first peer up, they exchange the route table data that they wish to inform each other of. Thereafter, they only send each other route information if anything changes. BGP and BGP4+ ASNs and AS_Path Attributes BGP and BGP4+ uses BGP path attributes (PAs). PAs define information about a path, or route, through a network. Some BGP and BGP4+ PAs describe information that is used to choose
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BGP and BGP4+ Introduction Internal and External BGP Concepts BGP defines two classes of neighbors (peers): internal BGP (iBGP) and external BGP (eBGP). These terms use the perspective of a single router, with the terms referring to whether a BGP neighbor is in the same ASN (iBGP) or a different ASN (eBGP). A BGP router behaves differently in several ways depending on whether the peer (neighbor) is an iBGP or eBGP peer. The differences include different rules about what must be true before t
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BGP and BGP4+ Introduction BGP is useful when you have at least two Internet connections. BGP is most useful when you want to choose one outbound path over another path for particular destinations in the Internet. Consider BGP when you have multiple Internet connections, where you want to make some packets take one path and you want other packets to take another path. External BGP (eBGP) Concepts This section describes the basics of eBGP to configure, verify, and advertise eBGP routes: ■ Exte
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BGP and BGP4+ Introduction How to verify eBGP Neighbor Status The two most common commands to display a BGP neighbor’s status are: show ip bgp summary (BGP) and show ip bgp neighbors (BGP). The show ip bgp neighbors (BGP) command shows detailed output per neighbor. The show ip bgp summary (BGP) command shows summary output per neighbor. Administratively Controlling Neighbor Status To administratively disable any BGP neighbor, enter BGP configuration mode with the router bgp command and iss
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BGP and BGP4+ Introduction Viewing a subset of the BGP Table When accepting full BGP updates, the number of BGP table entries may be too large for the show ip bgp (BGP) command listing thousands of prefixes. So instead use the show ip bgp summary (BGP) command that only lists the number of prefixes received from each neighbor. Advertising eBGP routes to ISPs Outbound routes let the Enterprise routers forward packets toward the Internet. At the same time, the ISPs need to learn routes for th
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BGP and BGP4+ Introduction Internal BGP (iBGP) Concepts Routers that run BGP often run an IGP, such as OSPF, and have learned routes for the public range either as one route or with subset routes. If a single route exists for the public range, then you can add a redistribute (into BGP or BGP4+) (BGP and BGP4+) command to the BGP configuration to redistribute that route, and only that route, into BGP. IGPs do not handle the public routing table. Internally peered BGP routers are capable of
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BGP and BGP4+ Introduction 4. Make sure each router has IP routes so that they can forward packets to the loopback interface IP address of the other router. Verifying iBGP iBGP neighbors use the same messages and neighbor states as eBGP peers. The same commands for BGP neighbor verification can be used to verify iBGP peers. The show ip bgp summary (BGP) command lists neighbors. The show ip bgp neighbors (BGP) and show bgp ipv6 neighbors (BGP4+) commands list many details specifically for the
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BGP and BGP4+ Introduction The synchronization feature tells a BGP router not to consider an iBGP-learned route as best unless the prefix is learned locally or via an IGP and is currently in the IP routing table. BGP synchronization prevents reachability issues by preventing a BGP router advertising routes learned from an iBGP peer unless the route is learned locally, or via an IGP. If the route does not exist in the routing table, because an IGP has not learned the route, then BGP will not
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BGP and BGP4+ Introduction How to configure BGP and BGP4+ This section describes BGP and BGP4+ configuration tasks and the commands required. For example configurations with sample topologies, see Chapter 2, BGP and BGP4+ Configuration. Initial BGP and BGP4+ Configuration Tasks There are two initial BGP and BGP4+ configuration tasks described in the below sections. More advanced BGP and BGP4+ configuration tasks are described later in this chapter and are also available separately in the How
