388
C
HAPTER
30: BGP C
ONFIGURATION
■
Using the
peer next-hop-local
command can specify the router as the next
hop for routes to a peer/peer group. If BGP load balancing is configured, the
router specify itself as the next hop for routes to a peer/peer group regardless
of whether the
peer next-hop-local
command is configured.
■
In a “third party next hop” network, that is, the two EBGP peers reside in a
common broadcast subnet, the BGP router does not specify itself as the next
hop for routes to the EBGP peer, unless the
peer next-hop-local
command is
configured.
■
In general, BGP checks whether the AS_PATH attribute of a route from a peer
contains the local AS number. If so, it discards the route to avoid routing loops.
■
You can specify a fake AS number to hide the real one as needed. The fake AS
number applies to routes to EBGP peers only, that is, EBGP peers in other ASs
can only find the fake AS number.
■
The
peer substitute-as
command is used only in specific networking
environments. Inappropriate use of the command may cause routing loops.
Tuning and
Optimizing BGP
Networks
This task involves the following parts:
1
Configure BGP timers
After establishing a BGP connection, two routers send keepalive messages
periodically to each other to keep the connection. If a router receives no keepalive
message from the peer after the holdtime elapses, it tears down the connection.
When establishing a BGP connection, the two parties compare their holdtime
values, taking the shorter one as the common holdtime.
2
Reset BGP connections
After modifying a route selection policy, you have to reset BGP connections to
make the new one take effect, causing short time disconnections. The current BGP
implementation supports the route-refresh capability. With this capability enabled
on all BGP routers in a network, when a policy is modified on a router, the router
advertises a route-refresh message to its peers, which then resend their routing
information to the router. Therefore, the local router can perform dynamic route
update and apply the new policy without tearing down BGP connections.
If a router not supporting route-refresh exists in the network, you must configure
the
peer keep-all-routes
command to save all route updates, and then use the
refresh bgp
command to soft-reset BGP connections, to refresh the BGP routing
table and apply the new policy without tearing down BGP connections.
3
Configure BGP authentication
BGP employs TCP as the transport protocol. To enhance security, you can
configure BGP to perform MD5 authentication when establishing a TCP
connection. BGP MD5 authentication is not for BGP packets. It is used to set
passwords for TCP connections. If the authentication fails, the TCP connection can
not be established.
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 ...