BGP Overview
379
The deficiency of confederation is: when changing an AS into a confederation,
you need to reconfigure your routers, and the topology will be changed.
In large-scale BGP networks, both route reflector and confederation can be used.
BGP GR
n
For GR (Graceful Restart) information, refer to “GR Overview” on page 247.
1
To establish a BGP session with a peer, a BGP GR Restarter sends an OPEN message
with GR capability to the peer.
2
Upon receipt of this message, the peer is aware that the sending router is capable
of Graceful Restart, and sends an OPEN message with GR Capability to the GR
Restarter to establish a GR session. If neither party has the GR capability, the
session established between them will not be GR capable.
3
The GR session between the GR Restarter and its peer goes down when the GR
Restarter restarts BGP. The GR capable peer will mark all routes associated with the
GR Restarter as stale. However, during the configured GR Time, it still uses these
routes for packet forwarding, ensuring that no packet will be lost when routing
information from its peer is recollected.
4
After the restart, the GR Restarter will reestablish a GR session with its peer and
send a new GR message notifying the completion of restart. Routing information
is exchanged between them for the GR Restarter to create a new routing table
and forwarding table with stale routing information removed. Thus the BGP
routing convergence is complete.
MP-BGP
Overview
The legacy BGP-4 supports IPv4, but does not support other network layer
protocols like IPv6.
To support more network layer protocols, IETF extended BGP-4 by introducing
Multiprotocol Extensions for BGP-4 (MP-BGP), which is defined in RFC2858.
Routers supporting MP-BGP can communicate with routers not supporting
MP-BGP.
MP-BGP extended attributes
In BGP-4, the three types of attributes for IPv4, namely NLRI, NEXT_HOP and
AGGREGATOR (contains the IP address of the speaker generating the summary
route) are all carried in updates.
To support multiple network layer protocols, BGP-4 puts information about
network layer into NLRI and NEXT_HOP. MP-BGP introduced two path attributes:
■
MP_REACH_NLRI: Multiprotocol Reachable NLRI, for advertising feasible routes
and next hops
■
MP_UNREACH_NLRI: Multiprotocol Unreachable NLRI, for withdrawing
unfeasible routes
Содержание 4800G Series
Страница 26: ...26 CHAPTER NETWORKING APPLICATIONS ...
Страница 30: ...30 CHAPTER 1 LOGGING IN TO AN ETHERNET SWITCH ...
Страница 62: ...62 CHAPTER 3 LOGGING IN THROUGH TELNET ...
Страница 70: ...70 CHAPTER 5 LOGGING IN THROUGH WEB BASED NETWORK MANAGEMENT SYSTEM ...
Страница 72: ...72 CHAPTER 6 LOGGING IN THROUGH NMS ...
Страница 82: ...82 CHAPTER 8 CONTROLLING LOGIN USERS ...
Страница 98: ...98 CHAPTER 9 VLAN CONFIGURATION ...
Страница 108: ...108 CHAPTER 10 VOICE VLAN CONFIGURATION ...
Страница 119: ...GVRP Configuration Examples 119 DeviceB display vlan dynamic No dynamic vlans exist ...
Страница 120: ...120 CHAPTER 11 GVRP CONFIGURATION ...
Страница 160: ...160 CHAPTER 17 PORT ISOLATION CONFIGURATION ...
Страница 172: ...172 CHAPTER 19 LINK AGGREGATION CONFIGURATION ...
Страница 196: ...196 CHAPTER 22 DLDP CONFIGURATION ...
Страница 240: ...240 CHAPTER 23 MSTP CONFIGURATION ...
Страница 272: ...272 CHAPTER 27 RIP CONFIGURATION ...
Страница 364: ...364 CHAPTER 29 IS IS CONFIGURATION ...
Страница 426: ...426 CHAPTER 31 ROUTING POLICY CONFIGURATION ...
Страница 442: ...442 CHAPTER 33 IPV6 RIPNG CONFIGURATION ...
Страница 466: ...466 CHAPTER 35 IPV6 IS IS CONFIGURATION ...
Страница 488: ...488 CHAPTER 36 IPV6 BGP CONFIGURATION ...
Страница 498: ...498 CHAPTER 37 ROUTING POLICY CONFIGURATION ...
Страница 540: ...540 CHAPTER 40 TUNNELING CONFIGURATION ...
Страница 552: ...552 CHAPTER 41 MULTICAST OVERVIEW ...
Страница 604: ...604 CHAPTER 43 MLD SNOOPING CONFIGURATION ...
Страница 628: ...628 CHAPTER 46 IGMP CONFIGURATION ...
Страница 699: ...Troubleshooting MSDP 699 4 Verify that the C BSR address is different from the anycast RP address ...
Страница 700: ...700 CHAPTER 48 MSDP CONFIGURATION ...
Страница 812: ...812 CHAPTER 57 DHCP SERVER CONFIGURATION ...
Страница 822: ...822 CHAPTER 58 DHCP RELAY AGENT CONFIGURATION ...
Страница 834: ...834 CHAPTER 61 BOOTP CLIENT CONFIGURATION ...
Страница 850: ...850 CHAPTER 63 IPV4 ACL CONFIGURATION ...
Страница 856: ...856 CHAPTER 64 IPV6 ACL CONFIGURATION ...
Страница 860: ...860 CHAPTER 65 QOS OVERVIEW ...
Страница 868: ...868 CHAPTER 66 TRAFFIC CLASSIFICATION TP AND LR CONFIGURATION ...
Страница 888: ...888 CHAPTER 69 PRIORITY MAPPING ...
Страница 894: ...894 CHAPTER 71 TRAFFIC MIRRORING CONFIGURATION ...
Страница 904: ...904 CHAPTER 72 PORT MIRRORING CONFIGURATION ...
Страница 930: ...930 CHAPTER 74 UDP HELPER CONFIGURATION ...
Страница 990: ...990 CHAPTER 79 FILE SYSTEM MANAGEMENT CONFIGURATION ...
Страница 1000: ...1000 CHAPTER 80 FTP CONFIGURATION ...
Страница 1020: ...1020 CHAPTER 82 INFORMATION CENTER CONFIGURATION ...
Страница 1038: ...1038 CHAPTER 84 SYSTEM MAINTAINING AND DEBUGGING ...
Страница 1046: ...1046 CHAPTER 85 DEVICE MANAGEMENT ...
Страница 1129: ...SSH Client Configuration Examples 1129 SwitchB ...
Страница 1130: ...1130 CHAPTER 88 SSH CONFIGURATION ...
Страница 1160: ...1160 CHAPTER 90 RRPP CONFIGURATION ...
Страница 1180: ...1180 CHAPTER 91 PORT SECURITY CONFIGURATION ...
Страница 1192: ...1192 CHAPTER 92 LLDP CONFIGURATION ...
Страница 1202: ...1202 CHAPTER 93 POE CONFIGURATION ...
Страница 1218: ...1218 CHAPTER 96 HTTPS CONFIGURATION ...