ON THIS PAGE
Example: Configuring BGP Large Communities
This example shows you to configure optional
transitive path attribute - a 12-byte BGP large community that provides
the most significant 4-byte value to encode autonomous system number
as the global administrator and the remaining two 4-byte assigned
numbers to encode the local values as defined in RFC 8092. You can
configure BGP large community at [edit policy-options community community-name members] and [edit routing-options
static route ip-address community] hierarchy
levels. The BGP large community attributes format has four fields: large:global administrator:assigned number:assigned number.
Requirements
This example uses the following hardware and software components:
Three MX Series routers
Junos OS Release 17.3 or later running on all devices
No special configuration beyond device initialization is required before configuring this example.
Overview
In this example, Device R1 and Device R2 are OSPF neighbors in autonomous system (AS) 64510. Device R3 has an external BGP (EBGP) connection to Device R1. Device R2 has customer networks in the 172.16/16 address space, simulated with addresses on its loopback interface (lo0). Device R1 has static routes to several 172.16.x/24 networks, and attaches regular community values to these routes. Device R1 then uses an export policy to advertise the routes to Device R3. Device R3 receives these routes and uses an import policy to add large community values to the routes.
Topology
Figure 1 shows the sample network.
Configuration
CLI Quick Configuration
To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.
Device R1
set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.1/30 set interfaces fe-1/2/3 unit 0 family inet address 10.0.0.14/30 set interfaces lo0 unit 0 family inet address 192.168.0.1/32 primary set routing-options static route 172.16.1.0/24 next-hop 10.0.0.2 set routing-options static route 172.16.1.0/24 community 64510:1 set routing-options static route 172.16.1.0/24 community large:64510:100:1 set routing-options static route 172.16.2.0/24 next-hop 10.0.0.2 set routing-options static route 172.16.2.0/24 community 64510:2 set routing-options static route 172.16.2.0/24 community large:64510:200:2 set routing-options static route 172.16.3.0/24 next-hop 10.0.0.2 set routing-options static route 172.16.3.0/24 community 64510:3 set routing-options static route 172.16.4.0/24 next-hop 10.0.0.2 set routing-options static route 172.16.4.0/24 community 64510:4 set routing-options router-id 192.168.0.1 set routing-options autonomous-system 64510 set protocols bgp group ext type external set protocols bgp group ext export send-static set protocols bgp group ext peer-as 64511 set protocols bgp group ext neighbor 10.0.0.13 set protocols ospf area 0.0.0.0 interface lo0.0 passive set protocols ospf area 0.0.0.0 interface fe-1/2/0.0 set policy-options policy-statement send-static term 1 from protocol static set policy-options policy-statement send-static term 1 then accept
Device R2
set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.2/30 set interfaces lo0 unit 0 family inet address 192.168.0.2/32 set interfaces lo0 unit 0 family inet address 172.16.1.1/32 set interfaces lo0 unit 0 family inet address 172.16.2.2/32 set interfaces lo0 unit 0 family inet address 172.16.3.3/32 set interfaces lo0 unit 0 family inet address 172.16.4.4/32 set routing-options router-id 192.168.0.2 set protocols ospf area 0.0.0.0 interface lo0.0 passive set protocols ospf area 0.0.0.0 interface fe-1/2/0.0
Device R3
set interfaces fe-1/2/3 unit 0 family inet address 10.0.0.13/30 set interfaces lo0 unit 0 family inet address 192.168.0.3/32 set routing-options router-id 192.168.0.3 set routing-options autonomous-system 64511 set protocols bgp group to-R1 type external set protocols bgp group to-R1 import set-large-comms set protocols bgp group to-R1 peer-as 64510 set protocols bgp group to-R1 neighbor 10.0.0.14 set policy-options policy-statement set-large-comms term route-1 from route-filter 172.16.1.0/24 exact set policy-options policy-statement set-large-comms term route-1 then community add large2-as set policy-options policy-statement set-large-comms term route-1 then accept set policy-options policy-statement set-large-comms term route-2 from route-filter 172.16.2.0/24 exact set policy-options policy-statement set-large-comms term route-2 then community add large2-ip set policy-options policy-statement set-large-comms term route-2 then accept set policy-options policy-statement set-large-comms term route-3 from route-filter 172.16.3.0/24 exact set policy-options policy-statement set-large-comms term route-3 then community add large1-as set policy-options policy-statement set-large-comms term route-3 then accept set policy-options policy-statement set-large-comms term route-4 from route-filter 172.16.4.0/24 exact set policy-options policy-statement set-large-comms term route-4 then community add large1-ip set policy-options policy-statement set-large-comms term route-4 then accept set policy-options community large1-as members large:64511:3:1 set policy-options community large1-ip members large:7777:4:1 set policy-options community large2-as members large:64511:1:1 set policy-options community large2-ip members large:7777:2:1
Procedure
Step-by-Step Procedure
The following example requires that you navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Use the CLI Editor in Configuration Mode in the Junos OS CLI User Guide.
To configure Device R3:
Configure the interfaces.
[edit interfaces] set fe-1/2/3 unit 0 family inet address 10.0.0.13/30 set lo0 unit 0 family inet address 192.168.0.3/32
Configure the autonomous system (AS) number and router ID.
[edit routing-options] set router-id 192.168.0.3 set autonomous-system 64511
Configure the EBGP connection to Device R1.
[edit protocols bgp group to-R1] set type external set import set-large-comms set peer-as 64510 set neighbor 10.0.0.14
Configure the policy that adds large community values to the routes received from Device R1.
A large community uses a notation of
large:global administrator:assigned number:assigned number. The specific community values can be anything that accomplishes your administrative goals, within certain parameters.[edit policy-options policy-statement set-large-comms] set term route-1 from route-filter 172.16.1.0/24 exact set term route-1 then community add large2-as set term route-1 then accept set term route-2 from route-filter 172.16.2.0/24 exact set term route-2 then community add large2-ip set term route-2 then accept set term route-3 from route-filter 172.16.3.0/24 exact set term route-3 then community add large1-as set term route-3 then accept set term route-4 from route-filter 172.16.4.0/24 exact set term route-4 then community add large1-ip set term route-4 then accept
[edit policy-options ] set community large1-as members large:64511:3:1 set community large1-ip members large:7777:4:1 set community large2-as members large:64511:1:1 set community large2-ip members large:7777:2:1
Results
From configuration mode, confirm your configuration
by entering the show interfaces, show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration,
repeat the instructions in this example to correct the configuration.
user@R3# show interfaces
fe-1/2/3 {
unit 0 {
family inet {
address 10.0.0.13/30;
}
}
}
lo0 {
unit 0 {
family inet {
address 192.168.0.3/32;
}
}
}
user@R3# show protocols
bgp {
group to-R1 {
type external;
import set-large-comms;
peer-as 64510;
neighbor 10.0.0.14;
}
}
user@R3# show policy-options
policy-statement set-large-comms {
term route-1 {
from {
route-filter 172.16.1.0/24 exact;
}
then {
community add large2-as;
accept;
}
}
term route-2 {
from {
route-filter 172.16.2.0/24 exact;
}
then {
community add large2-ip;
accept;
}
}
term route-3 {
from {
route-filter 172.16.3.0/24 exact;
}
then {
community add large1-as;
accept;
}
}
term route-4 {
from {
route-filter 172.16.4.0/24 exact;
}
then {
community add large1-ip;
accept;
}
}
}
community large1-as members large:64511:3:1;
community large1-ip members large:7777:4:1;
community large2-as members large:64511:1:1;
community large2-ip members large:7777:2:1;
user@R3# show routing-options router-id 192.168.0.3; autonomous-system 64511;
If you are done configuring the device, enter commit from configuration mode.
Verification
Confirm that the configuration is working properly.
Verifying R1
Purpose
On Device R1, check the 172.16. routes in the routing table.
Action
user@R1> show route protocol static match-prefix 172.16.* detail
inet.0: 17 destinations, 17 routes (17 active, 0 holddown, 0 hidden)
172.16.1.0/24 (1 entry, 1 announced)
*Static Preference: 5
Next hop type: Router, Next hop index: 580
Address: 0xb7a1270
Next-hop reference count: 9
Next hop: 10.0.0.2 via fe-1/2/0.0, selected
Session Id: 0x140
State: < Active Int Ext >
Local AS: 64510
Age: 4d 19:02:23
Validation State: unverified
Task: RT
Announcement bits (2): 0-KRT 4-BGP_RT_Background
AS path: I
Communities: 64510:1 large:64510:100:1
172.16.2.0/24 (1 entry, 1 announced)
*Static Preference: 5
Next hop type: Router, Next hop index: 580
Address: 0xb7a1270
Next-hop reference count: 9
Next hop: 10.0.0.2 via fe-1/2/0.0.0, selected
Session Id: 0x140
State: < Active Int Ext >
Local AS: 64510
Age: 4d 19:02:23
Validation State: unverified
Task: RT
Announcement bits (2): 0-KRT 4-BGP_RT_Background
AS path: I
Communities: 64510:2 large:64510:200:2
172.16.3.0/24 (1 entry, 1 announced)
*Static Preference: 5
Next hop type: Router, Next hop index: 580
Address: 0xb7a1270
Next-hop reference count: 9
Next hop: 10.0.0.2 via fe-1/2/0.0.0, selected
Session Id: 0x140
State: < Active Int Ext >
Local AS: 64510
Age: 4d 22:17:12
Validation State: unverified
Task: RT
Announcement bits (2): 0-KRT 4-BGP_RT_Background
AS path: I
Communities: 64510:3
172.16.4.0/24 (1 entry, 1 announced)
*Static Preference: 5
Next hop type: Router, Next hop index: 580
Address: 0xb7a1270
Next-hop reference count: 9
Next hop: 10.0.0.2 via fe-1/2/0.0.0, selected
Session Id: 0x140
State: < Active Int Ext >
Local AS: 64510
Age: 4d 22:17:12
Validation State: unverified
Task: RT
Announcement bits (2): 0-KRT 4-BGP_RT_Background
AS path: I
Communities: 64510:4
. . .
Meaning
The output shows that the regular community and large community values are attached to the routes.
The communities are attached to static routes, thus demonstrating that both regular and large communities can be attached to static routes.
Verifying R3
Purpose
On Device R3, check the 172.16. routes in the routing table.
Action
user@R3> show route protocol bgp match-prefix 172.16.* detail
inet.0: 14 destinations, 14 routes (14 active, 0 holddown, 0 hidden)
172.16.1.0/24 (1 entry, 1 announced)
*BGP Preference: 170/-101
Next hop type: Router, Next hop index: 581
Address: 0xb7a10f0
Next-hop reference count: 8
Source: 10.0.0.14
Next hop: 10.0.0.14 via fe-1/2/3.0, selected
Session Id: 0x140
State: < Active Ext >
Local AS: 64511 Peer AS: 64510
Age: 3d 16:36:18
Validation State: unverified
Task: BGP_64510.10.0.0.14
Announcement bits (1): 0-KRT
AS path: 64510 I
Communities: 64510:1 large:64510:100:1 large:64511:1:1
Accepted
Localpref: 100
Router ID: 192.168.0.1
172.16.2.0/24 (1 entry, 1 announced)
*BGP Preference: 170/-101
Next hop type: Router, Next hop index: 581
Address: 0xb7a10f0
Next-hop reference count: 8
Source: 10.0.0.14
Next hop: 10.0.0.14 via fe-1/2/3.0, selected
Session Id: 0x140
State: < Active Ext >
Local AS: 64511 Peer AS: 64510
Age: 3d 16:36:18
Validation State: unverified
Task: BGP_64510.10.0.0.14
Announcement bits (1): 0-KRT
AS path: 64510 I
Communities: 64510:2 large:7777:2:1 large:64510:200:2
Accepted
Localpref: 100
Router ID: 192.168.0.1
172.16.3.0/24 (1 entry, 1 announced)
*BGP Preference: 170/-101
Next hop type: Router, Next hop index: 581
Address: 0xb7a10f0
Next-hop reference count: 8
Source: 10.0.0.14
Next hop: 10.0.0.14 via fe-1/2/3.0, selected
Session Id: 0x140
State: < Active Ext >
Local AS: 64511 Peer AS: 64510
Age: 3d 16:36:18
Validation State: unverified
Task: BGP_64510.10.0.0.14
Announcement bits (1): 0-KRT
AS path: 64510 I
Communities: 64510:3 large:64511:3:1
Accepted
Localpref: 100
Router ID: 192.168.0.1
172.16.4.0/24 (1 entry, 1 announced)
*BGP Preference: 170/-101
Next hop type: Router, Next hop index: 581
Address: 0xb7a10f0
Next-hop reference count: 8
Source: 10.0.0.14
Next hop: 10.0.0.14 via fe-1/2/3.0, selected
Session Id: 0x140
State: < Active Ext >
Local AS: 64511 Peer AS: 64510
Age: 3d 16:36:18
Validation State: unverified
Task: BGP_64510.10.0.0.14
Announcement bits (1): 0-KRT
AS path: 64510 I
Communities: 64510:4 large:7777:4:1
Accepted
Localpref: 100
Router ID: 192.168.0.1
. . .
Meaning
The output shows that the advertised regular and large community values remain attached to the routes, and that the new large community values are added when received by R3.