Below
is the configuration example for None Community. As we have seen in previous examples that Community is the attribute which can be used to apply policies on
he routes.
Instead
of matching individual routes to apply policy we can use community to reduce
the repetitive work.
We
just need to match route community and apply policy to it. All routes which has
the community will apply the policy automatically.
None
community is used to remove all community from the routes which are in there.
As
per our above example. R1 is setting NO-ADVERTISE community on the routes and
sending it to R2. R2 are not sending any routes with NO-ADVERTISE community to
any neighbor.
To
advertise R1 Routes from R2 to R3 and R5, I just set the community none to
neighbor R1. What it will do is, it will remove the NO-ADVERTISE community from
R1 routes and hence R2 will be able to send R1 routes to R3/R5.
Routing
table of R3/R4/R5 can confirm the above statement.
R1:-
interface
Loopback0
ip address 1.1.1.1 255.255.255.255
interface
FastEthernet2/0
Description
“ Connected to R2”
ip address 12.12.12.1 255.255.255.0
no shut
router bgp 1
no synchronization
bgp log-neighbor-changes
network 1.1.1.1 mask 255.255.255.255
neighbor 12.12.12.2 remote-as 2
neighbor 12.12.12.2 send-community both --<<
Without it Community will not send to neighbor
neighbor 12.12.12.2 route-map setCommunity out
no auto-summary
route-map
setCommunity permit 10
set community no-advertise
R2:-
interface
Loopback0
ip address 2.2.2.2 255.255.255.255
interface
FastEthernet0/0
ip address 23.23.23.2 255.255.255.0
speed auto
duplex auto
interface
FastEthernet1/0
Description
“Connected to R5”
ip address 25.25.25.2 255.255.255.0
no shut
interface
FastEthernet2/0
Description
“Connected to R1”
ip address 12.12.12.2 255.255.255.0
no shut
Router eigrp
2 ----<<
To provide connectivity between AS2 Routers
network 23.23.23.2 0.0.0.0
router bgp 2
no synchronization
bgp log-neighbor-changes
network 2.2.2.2 mask 255.255.255.255
neighbor 12.12.12.1 remote-as 1
neighbor 23.23.23.3 remote-as 2
neighbor 23.23.23.3 next-hop-self
neighbor 23.23.23.3 send-community both
neighbor 25.25.25.5 remote-as 3
no auto-summary
Without None Community:-
R2#sh ip bgp
1.1.1.1
BGP routing
table entry for 1.1.1.1/32, version 2
Paths: (1
available, best #1, table default, not advertised to any peer)
Not advertised to any peer
1
12.12.12.1 from 12.12.12.1 (1.1.1.1)
Origin IGP, metric 0, localpref 100,
valid, external, best
Community: no-advertise --<<
Learning Community which is set by R1
Set None Community:-
router bgp 2
neighbor
12.12.12.1 route-map None_Community in
route-map
None_Community permit 10
set community none --<<<
Setiing none community to all R1 routes
R2#sh ip bgp
1.1.1.1 --<<<
No Community is visible now.
BGP routing
table entry for 1.1.1.1/32, version 7
Paths: (1
available, best #1, table default)
Advertised to update-groups:
1
2
1
12.12.12.1 from 12.12.12.1 (1.1.1.1)
Origin IGP, metric 0, localpref 100,
valid, external, best
R3:-
interface
Loopback0
ip address 3.3.3.3 255.255.255.255
interface
FastEthernet0/1
Description
“Connected to R4”
ip address 34.34.34.3 255.255.255.0
no shut
interface
FastEthernet0/0
Description
“Connected to R3”
ip address 23.23.23.3 255.255.255.0
no shut
router eigrp
2
network 23.23.23.3 0.0.0.0
network 34.34.34.3 0.0.0.0
router bgp 2
no synchronization
bgp log-neighbor-changes
network 3.3.3.3 mask 255.255.255.255
neighbor 23.23.23.2 remote-as 2
neighbor 23.23.23.2 route-reflector-client --<< R3 is
RR for R2 and R4
neighbor 34.34.34.4 remote-as 2
neighbor 34.34.34.4 route-reflector-client --<< R3 is RR for R2 and R4
neighbor 34.34.34.4 send-community both
no auto-summary
R4:-
interface
Loopback0
ip address 4.4.4.4 255.255.255.255
interface
FastEthernet0/1
Description
“Connected to R4”
ip address 34.34.34.4 255.255.255.0
router eigrp
2
network 34.34.34.4 0.0.0.0
!
router bgp 2
no synchronization
bgp log-neighbor-changes
network 4.4.4.4 mask 255.255.255.255
neighbor 34.34.34.3 remote-as 2
no auto-summary
R5:-
interface
Loopback0
ip address 5.5.5.5 255.255.255.255
interface
FastEthernet1/0
Description
“Connected to R2”
ip address 25.25.25.5 255.255.255.0
router bgp 3
no synchronization
bgp log-neighbor-changes
network 5.5.5.5 mask 255.255.255.255
neighbor 25.25.25.2 remote-as 2
no auto-summary
Verification:-
R1:-
R1#sh ip
route
Codes: L -
local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O -
OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 -
OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF
external type 2
i - IS-IS, su - IS-IS summary, L1 -
IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate
default, U - per-user static route
o - ODR, P - periodic downloaded static
route, H - NHRP
+ - replicated route, % - next hop
override
Gateway of
last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected,
Loopback0
2.0.0.0/32 is subnetted, 1 subnets
B 2.2.2.2 [20/0] via 12.12.12.2, 00:31:49
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [20/0] via 12.12.12.2, 00:11:38
5.0.0.0/32 is subnetted, 1 subnets
B 5.5.5.5 [20/0] via 12.12.12.2, 00:31:18
12.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 12.12.12.0/24 is directly connected,
FastEthernet2/0
L 12.12.12.1/32 is directly connected,
FastEthernet2/0
R1#sh ip bgp
BGP table
version is 5, local router ID is 1.1.1.1
Status
codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m
multipath, b backup-path, x best-external
Origin
codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>
1.1.1.1/32 0.0.0.0 0 32768 I --<<< R1 advertising Lo0
*>
2.2.2.2/32 12.12.12.2 0 0 2 i
*>
3.3.3.3/32 12.12.12.2 0 2 i
*>
5.5.5.5/32 12.12.12.2 0 2 3 i
R1#sh ip bgp
summary
BGP router
identifier 1.1.1.1, local AS number 1
BGP table
version is 5, main routing table version 5
4 network
entries using 512 bytes of memory
4 path
entries using 208 bytes of memory
4/4 BGP
path/bestpath attribute entries using 496 bytes of memory
2 BGP
AS-PATH entries using 48 bytes of memory
0 BGP
route-map cache entries using 0 bytes of memory
0 BGP
filter-list cache entries using 0 bytes of memory
BGP using
1264 total bytes of memory
BGP activity
4/0 prefixes, 4/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer
InQ OutQ Up/Down State/PfxRcd
12.12.12.2 4 2 40
41 5 0
0 00:33:03 3
R2:-
R2#sh ip
route
Codes: L -
local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O -
OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 -
OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF
external type 2
i - IS-IS, su - IS-IS summary, L1 -
IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate
default, U - per-user static route
o - ODR, P - periodic downloaded static
route, H - NHRP
+ - replicated route, % - next hop
override
Gateway of
last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [20/0] via 12.12.12.1, 00:24:33
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected,
Loopback0
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [200/0] via 23.23.23.3,
00:12:16
5.0.0.0/32 is subnetted, 1 subnets
B 5.5.5.5 [20/0] via 25.25.25.5, 00:32:26
12.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 12.12.12.0/24 is directly connected,
FastEthernet2/0
L 12.12.12.2/32 is directly connected,
FastEthernet2/0
23.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 23.23.23.0/24 is directly connected,
FastEthernet0/0
L 23.23.23.2/32 is directly connected,
FastEthernet0/0
25.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 25.25.25.0/24 is directly connected,
FastEthernet1/0
L 25.25.25.2/32 is directly connected,
FastEthernet1/0
R2#sh ip bgp
BGP table
version is 6, local router ID is 2.2.2.2
Status
codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath,
b backup-path, x best-external
Origin
codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>
1.1.1.1/32 12.12.12.1 0 0 1 i
*>
2.2.2.2/32 0.0.0.0 0
32768 i
*>i3.3.3.3/32 23.23.23.3 0 100
0 i
*
i4.4.4.4/32 34.34.34.4 0 100
0 i
*>
5.5.5.5/32 25.25.25.5 0 0 3 i
R2#sh ip bgp
su
R2#sh ip bgp
summary
BGP router
identifier 2.2.2.2, local AS number 2
BGP table
version is 6, main routing table version 6
5 network
entries using 640 bytes of memory
5 path
entries using 260 bytes of memory
4/4 BGP
path/bestpath attribute entries using 496 bytes of memory
1 BGP rrinfo
entries using 24 bytes of memory
2 BGP
AS-PATH entries using 48 bytes of memory
1 BGP
community entries using 24 bytes of memory
0 BGP
route-map cache entries using 0 bytes of memory
0 BGP
filter-list cache entries using 0 bytes of memory
BGP using 1492
total bytes of memory
BGP activity
5/0 prefixes, 5/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer
InQ OutQ Up/Down State/PfxRcd
12.12.12.1 4 1 41
41 6 0
0 00:33:42 1
23.23.23.3 4 2 19
19 6 0
0 00:12:24 2
25.25.25.5 4 3 41
41 6 0
0 00:33:01 1
R2#sh ip bgp
1.1.1.1
BGP routing
table entry for 1.1.1.1/32, version 5
Paths: (1
available, best #1, table default, not advertised to any peer)
Not advertised to any peer
1
12.12.12.1 from 12.12.12.1 (1.1.1.1)
Origin IGP, metric 0, localpref 100,
valid, external, best
Community: no-advertise -<<<
without None Community Learning Community which is set on R1
R2#sh ip bgp
1.1.1.1 --<<
No Community is visible with None Community
BGP routing
table entry for 1.1.1.1/32, version 7
Paths: (1
available, best #1, table default)
Advertised to update-groups:
1
2
1
12.12.12.1 from 12.12.12.1 (1.1.1.1)
Origin IGP, metric 0, localpref 100,
valid, external, best
R3:-
R3#sh ip bgp
BGP table
version is 6, local router ID is 3.3.3.3
Status
codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m
multipath, b backup-path, x best-external
Origin
codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i1.1.1.1/32 23.23.23.2 0 100
0 1 I ----<<<<<
R1 routes
*>i2.2.2.2/32 23.23.23.2 0 100
0 i
*>
3.3.3.3/32 0.0.0.0 0
32768 i
*>i4.4.4.4/32 34.34.34.4 0 100
0 i
*>i5.5.5.5/32 23.23.23.2 0 100
0 3 i
R3#sh ip
route
Codes: L -
local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D
- EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 -
OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF
external type 2
i - IS-IS, su - IS-IS summary, L1 -
IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate
default, U - per-user static route
o - ODR, P - periodic downloaded static
route, H - NHRP
+ - replicated route, % - next hop
override
Gateway of
last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [200/0] via 23.23.23.2,
00:13:28
2.0.0.0/32 is subnetted, 1 subnets
B 2.2.2.2 [200/0] via 23.23.23.2,
00:15:55
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected,
Loopback0
4.0.0.0/32 is subnetted, 1 subnets
B 4.4.4.4 [200/0] via 34.34.34.4,
00:15:55
5.0.0.0/32 is subnetted, 1 subnets
B 5.5.5.5 [200/0] via 23.23.23.2,
00:15:55
12.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 12.12.12.0/24 is directly connected,
FastEthernet2/0
L 12.12.12.2/32 is directly connected,
FastEthernet2/0
23.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 23.23.23.0/24 is directly connected,
FastEthernet0/0
L 23.23.23.3/32 is directly connected,
FastEthernet0/0
25.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 25.25.25.0/24 is directly connected,
FastEthernet1/0
L 25.25.25.2/32 is directly connected,
FastEthernet1/0
34.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 34.34.34.0/24 is directly connected,
FastEthernet0/1
L 34.34.34.3/32 is directly connected,
FastEthernet0/1
R3#sh ip bgp
summary
BGP router
identifier 3.3.3.3, local AS number 2
BGP table
version is 6, main routing table version 6
5 network
entries using 640 bytes of memory
5 path
entries using 260 bytes of memory
4/4 BGP
path/bestpath attribute entries using 496 bytes of memory
2 BGP
AS-PATH entries using 48 bytes of memory
0 BGP
route-map cache entries using 0 bytes of memory
0 BGP
filter-list cache entries using 0 bytes of memory
BGP using
1444 total bytes of memory
BGP activity
5/0 prefixes, 5/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer
InQ OutQ Up/Down State/PfxRcd
23.23.23.2 4 2 24
25 6 0
0 00:16:53 3
34.34.34.4 4 2 22
24 6 0
0 00:16:57 1
R4:-
R4#sh ip bgp
BGP table
version is 6, local router ID is 4.4.4.4
Status
codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m
multipath, b backup-path, x best-external
Origin
codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i1.1.1.1/32 23.23.23.2 0 100
0 1 i
*>i2.2.2.2/32 23.23.23.2 0 100
0 i
*>i3.3.3.3/32 34.34.34.3 0 100
0 i
*>
4.4.4.4/32 0.0.0.0 0 32768 i
*>i5.5.5.5/32 23.23.23.2 0 100
0 3 i
R4#sh ip
route
Codes: L -
local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O -
OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 -
OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF
external type 2
i - IS-IS, su - IS-IS summary, L1 -
IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate
default, U - per-user static route
o - ODR, P - periodic downloaded static
route, H - NHRP
+ - replicated route, % - next hop
override
Gateway of
last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [200/0] via 23.23.23.2,
00:14:55
2.0.0.0/32 is subnetted, 1 subnets
B 2.2.2.2 [200/0] via 23.23.23.2,
00:17:22
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [200/0] via 34.34.34.3,
00:17:22
4.0.0.0/32 is subnetted, 1 subnets
C 4.4.4.4 is directly connected,
Loopback0
5.0.0.0/32 is subnetted, 1 subnets
B 5.5.5.5 [200/0] via 23.23.23.2,
00:17:22
23.0.0.0/24 is subnetted, 1 subnets
D 23.23.23.0 [90/30720] via 34.34.34.3,
00:18:26, FastEthernet0/1
34.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 34.34.34.0/24 is directly connected,
FastEthernet0/1
L 34.34.34.4/32 is directly connected,
FastEthernet0/1
45.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 45.45.45.0/24 is directly connected,
FastEthernet2/0
L 45.45.45.4/32 is directly connected,
FastEthernet2/0
R4#sh ip bgp
summary
BGP router
identifier 4.4.4.4, local AS number 2
BGP table
version is 6, main routing table version 6
5 network
entries using 640 bytes of memory
5 path
entries using 260 bytes of memory
4/4 BGP
path/bestpath attribute entries using 496 bytes of memory
1 BGP rrinfo
entries using 24 bytes of memory
2 BGP AS-PATH
entries using 48 bytes of memory
0 BGP
route-map cache entries using 0 bytes of memory
0 BGP
filter-list cache entries using 0 bytes of memory
BGP using
1468 total bytes of memory
BGP activity
5/0 prefixes, 5/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer
InQ OutQ Up/Down State/PfxRcd
34.34.34.3 4 2 26
24 6 0
0 00:18:25 4
R5:-
R5#sh ip bgp
BGP table
version is 1, local router ID is 5.5.5.5
Status
codes: s suppressed, d damped, h history, * valid, > best, i - in
ternal,
r RIB-failure, S Stale, m
multipath, b backup-path, x best
-external
Origin
codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
* 5.5.5.5/32 0.0.0.0 0 32768 i
R5#sh ip bgp
BGP table
version is 7, local router ID is 5.5.5.5
Status
codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m
multipath, b backup-path, x best-external
Origin
codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>
1.1.1.1/32 25.25.25.2 0 2 1 i
*>
2.2.2.2/32 25.25.25.2 0 0 2 i
*>
3.3.3.3/32 25.25.25.2 0 2 i
*>
4.4.4.4/32 25.25.25.2 0 2 i
*>
5.5.5.5/32 0.0.0.0 0 32768 i
R5#sh ip
route
Codes: L -
local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O -
OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 -
OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF
external type 2
i - IS-IS, su - IS-IS summary, L1 -
IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate
default, U - per-user static route
o - ODR, P - periodic downloaded static
route, H - NHRP
+ - replicated route, % - next hop
override
Gateway of
last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [20/0] via 25.25.25.2, 00:15:44
2.0.0.0/32 is subnetted, 1 subnets
B 2.2.2.2 [20/0] via 25.25.25.2, 00:18:12
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [20/0] via 25.25.25.2, 00:17:41
4.0.0.0/32 is subnetted, 1 subnets
B 4.4.4.4 [20/0] via 25.25.25.2, 00:17:41
5.0.0.0/32 is subnetted, 1 subnets
C 5.5.5.5 is directly connected,
Loopback0
25.0.0.0/8 is variably subnetted, 2
subnets, 2 masks
C 25.25.25.0/24 is directly connected,
FastEthernet1/0
L 25.25.25.5/32 is directly connected,
FastEthernet1/0
R5#sh ip bgp
summary
BGP router
identifier 5.5.5.5, local AS number 3
BGP table
version is 7, main routing table version 7
5 network
entries using 640 bytes of memory
5 path
entries using 260 bytes of memory
4/4 BGP
path/bestpath attribute entries using 496 bytes of memory
2 BGP
AS-PATH entries using 48 bytes of memory
0 BGP
route-map cache entries using 0 bytes of memory
0 BGP
filter-list cache entries using 0 bytes of memory
BGP using
1444 total bytes of memory
BGP activity
5/0 prefixes, 5/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer
InQ OutQ Up/Down State/PfxRcd
25.25.25.2 4
2 28
26 7 0
0 00:19:12 4
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