
C
HAPTER
51
| IP Routing Commands
Border Gateway Protocol (BGPv4)
– 1823 –
zero by both peers, a BGP session can be kept open without generating
KEEPALIVE messages.
R
OUTE
A
GGREGATION
AND
D
ISSEMINATION
In the Internet, the number of destinations is larger than most routing
protocols can manage. It is not possible for routers to track every possible
destination in their routing tables. To overcome this problem BGP relies on
route aggregation, whereby multiple destinations are combined in a single
advertisement. Routers receiving this information, treat the combined
destinations as a single destination, thus reducing the number of individual
routes that must be remembered. This also reduces the network overhead
required to transmit update packets and maintain routing tables.
In BGP, route aggregation combines the address blocks for networks from
two or more ASes into a supernet, and transmits this information to a
downstream AS. This supernetted address block is less specific, and only
lists the AS number of the AS where the supernetting was done. The
Atomic_Aggregate attribute indicates that attributes for more specific
paths are not included in the aggregated route, and the Aggregator
attribute indicates the AS and router where the aggregation was done. The
aggregator node will now serve as a proxy, using the more specific routes it
still maintains in its own routing table.
After inbound routes have been aggregated, the BGP speaker can
propagates this information based on export policies for individual
neighbors or for defined router groups, using route maps or other more
precise routing criteria.
I
NTERNAL
BGP
S
CALABILITY
An iBGP speaker cannot advertise IP prefixes it has learned from one iBGP
speaker to another neighboring iBGP speaker. iBGP therefore requires full-
mesh connectivity among all iBGP speakers. For local networks containing
a large number of speakers, this requirement may be difficult to meet.
There are several commonly used approaches to resolving this problem,
including route reflectors, confederations, and route servers.
Содержание ECS4660-28F
Страница 1: ...Management Guide www edge core com ECS4660 28F Layer 3 Gigabit Ethernet Switch...
Страница 2: ......
Страница 4: ......
Страница 12: ...ABOUT THIS GUIDE 12...
Страница 64: ...CONTENTS 64...
Страница 90: ...TABLES 90...
Страница 92: ...SECTION I Getting Started 92...
Страница 122: ...SECTION II Web Configuration 122 Multicast Routing on page 825...
Страница 148: ...CHAPTER 3 Using the Web Interface Navigating the Web Browser Interface 148...
Страница 224: ...CHAPTER 5 Interface Configuration VLAN Trunking 224 Figure 68 Configuring VLAN Trunking...
Страница 262: ...CHAPTER 6 VLAN Configuration Configuring VLAN Translation 262...
Страница 304: ...CHAPTER 9 Congestion Control Automatic Traffic Control 304...
Страница 340: ...CHAPTER 11 Quality of Service Attaching a Policy Map to a Port 340...
Страница 452: ...CHAPTER 13 Security Measures DHCP Snooping 452...
Страница 740: ...CHAPTER 17 IP Services Configuring the PPPoE Intermediate Agent 740...
Страница 866: ...CHAPTER 21 Multicast Routing Configuring PIMv6 for IPv6 866...
Страница 882: ...CHAPTER 22 Using the Command Line Interface CLI Command Groups 882...
Страница 1024: ...CHAPTER 26 Remote Monitoring Commands 1024...
Страница 1030: ...CHAPTER 27 Flow Sampling Commands 1030...
Страница 1088: ...CHAPTER 28 Authentication Commands PPPoE Intermediate Agent 1088...
Страница 1162: ...CHAPTER 29 General Security Measures Configuring Port based Traffic Segmentation 1162...
Страница 1186: ...CHAPTER 30 Access Control Lists ACL Information 1186...
Страница 1214: ...CHAPTER 31 Interface Commands Transceiver Threshold Configuration 1214...
Страница 1238: ...CHAPTER 33 Port Mirroring Commands RSPAN Mirroring Commands 1238...
Страница 1258: ...CHAPTER 34 Congestion Control Commands Automatic Traffic Control Commands 1258...
Страница 1270: ...CHAPTER 36 UniDirectional Link Detection Commands 1270...
Страница 1276: ...CHAPTER 37 Address Table Commands 1276...
Страница 1336: ...CHAPTER 39 ERPS Commands 1336...
Страница 1386: ...CHAPTER 40 VLAN Commands Configuring Voice VLANs 1386...
Страница 1406: ...CHAPTER 41 Class of Service Commands Priority Commands Layer 3 and 4 1406...
Страница 1424: ...CHAPTER 42 Quality of Service Commands 1424...
Страница 1536: ...CHAPTER 43 Multicast Filtering Commands MLD Proxy Routing 1536...
Страница 1602: ...CHAPTER 45 CFM Commands Delay Measure Operations 1602...
Страница 1624: ...CHAPTER 47 Domain Name Service Commands 1624...
Страница 1646: ...CHAPTER 48 DHCP Commands DHCP Server 1646...
Страница 1974: ...SECTION IV Appendices 1974...
Страница 1980: ...APPENDIX A Software Specifications Management Information Bases 1980...
Страница 2020: ...ECS4660 28F E102013 ST R03 149100000140A...