3Com Router User Manual

Configuring BGP 467
Ta b l e 551   Allow the Import of Network 0.0.0.0 into the BGP
By default, the import of network 0.0.0.0 into BGP is disabled.
Defining an Access List 
Entry, an AS Path-list 
Entry, a Routing PolicyThis section describes the configuration of an access list, an AS path list, and a 
routing policy.
Define an access list entry
See “Access Control List” in ****need proper ref here 3Com Router Operation 
Manual (Security Configuration)******. for more details.
Define an AS Path-list...

468CHAPTER 30: CONFIGURING BGP
Perform the following configurations in system view.
Ta b l e 553   Define a Routing Policy
Define a match rule
Perform the following configurations in BGP Routing policy view.
Ta b l e 554   Define a Match Rules
By default, AS regular expression, community list, interface type, IP address range, 
and metric value are not matched.
See “Define matching rules” of “Configuration of IP Routing Policy” for details.
Define an apply clause
Perform the following configurations in...

Configuring BGP 469
By default, AS serial number, BGP community attribute, next hop, local preference, 
metric value, and origin attributes are not applied.
See “Define Apply Clause “of “Configuration of IP Routing Policy” for details.
Configuring a Route 
Filter for BGPPerform the following configurations in BGP view.
Configure a route filter for information received by BGP
Ta b l e 556   Filter Routing Information Received from BGP
Set the communities attributesapply community { { [aa:nn ] [...

470CHAPTER 30: CONFIGURING BGP
Configure Filtering Route Information being Advertised by BGP
Ta b l e 557   Filter Routing Information Being Advertised by BGP
By default, BGP does not filter any route information that is received or advertised.
protocol specifies the routing domain that can will be filtered. At present, BGP 
can filter route domains such as connected, static, OSPF and OSPF-ASE.
See “Configure Route Filter” of “Configuration of IP Routing Policy” for details.
Resetting BGP...

BGP Configuration Example471
BGP Configuration 
ExampleThis section describes several different configurations of BGP with a suggested 
procedure for each configuration.
Configuring the AS 
Confederation AttributeAs shown in the following diagram, AS 100 is divided into 3 sub-ASs: 1001, 1002, 
1003, which are configured with EBGP, confederation EBGP and IBGP.
Display route flap informationdisplay bgp routing-table 
flap-information [ { 
regular-expression 
as-regular-expression } | { acl 
acl-number } |...

472CHAPTER 30: CONFIGURING BGP
Figure 154   Networking diagram of configuring AS confederation 
1Configure Router A:
[RouterA] bgp 1001
[RouterA-bgp] undo synchronization
[RouterA-bgp] confederation id 100
[RouterA-bgp] confederation peer-as 1002 1003
[RouterA-bgp] peer 172.68.10.2 as-number 1002
[RouterA-bgp] peer 172.68.10.3 as-number 1003
2Configure Router B:
[RouterB] bgp 1002
[RouterA-bgp] undo synchronization
[RouterB-bgp] confederation id 100
[RouterB-bgp] confederation peer-as 1001 1003...

BGP Configuration Example473
Figure 155   Networking diagram of configuring route reflector
1Configure Router A:
[RouterA] bgp 100
[RouterA-bgp] undo synchronization
[RouterA-bgp] peer 192.1.1.2 as-number 200
[RouterA-bgp] interface serial 0
[RouterA-Serial0] ip address 192.1.1.1 255.255.255.0
2Configure Router B:
aConfigure BGP peers 
[RouterB] bgp 200
[RouterA-bgp] undo synchronization
[RouterB-bgp] peer 192.1.1.1 as-number 100
[RouterB-bgp] peer 193.1.1.1 as-number 200
bEnable OSPF
[RouterB] ospf...

474CHAPTER 30: CONFIGURING BGP
[RouterC-Serial0] ip address 193.1.1.1 255.255.255.0
dConfigure Serial 1
[RouterC-Serial0] interface serial 1
[RouterC-Serial1] ip address 194.1.1.1 255.255.255.0
[RouterC-Serial1] ospf enable area 0
4Configure Router D:
aConfigure BGP peers 
[RouterD] bgp 200
[RouterA-bgp] undo synchronization
[RouterD-bgp] peer 194.1.1.1 as-number 200 
bEnable OSPF
[RouterD] ospf enable 
cConfigure Serial 0
[RouterD-ospf] interface serial 0
[RouterD-Serial0] ip address 194.1.1.2...

BGP Configuration Example475
Figure 156   Networking diagram of configuring BGP path selection
1Configure Router A:
[RouterA] interface serial 0
[RouterA-Serial0] ip address 192.1.1.1 255.255.255.0
[RouterA] interface serial 1
[RouterA-Serial1] ip address 193.1.1.1 255.255.255.0
[RouterA-Serial1] quit
aStart BGP
[RouterA] bgp 100
[RouterA-bgp] undo synchronization
bSpecify BGP transmission network
[RouterA-bgp] network 1.0.0.0 mask 255.0.0.0
[RouterA-bgp] network 2.0.0.0 mask 255.0.0.0
cConfigure peer...

476CHAPTER 30: CONFIGURING BGP
2Configure Router B:
[RouterB] interface serial 0
[RouterB-Serial0] ip address 192.1.1.2 255.255.255.0
[RouterB] interface serial 1
[RouterB-Serial1] ip address 194.1.1.2 255.255.255.0
[RouterB] ospf enable
[RouterB-ospf] network 194.1.1.0 0.0.0.255 area 0
[RouterB-ospf] network 192.1.1.0 0.0.0.255 area 0
[RouterB] bgp 200
[RouterB-bgp] undo synchronization
[RouterB-bgp] peer 192.1.1.1.1 as-number 100
[RouterB-bgp] peer 194.1.1.1.1 as-number 200
[RouterB-bgp] peer...