Below are the characteristics of weight:-
1.
Manipulate Outgoing traffic
Manipulate Outgoing traffic
2.
Cisco Proprietary
Cisco Proprietary
3.
Only applicable when two exit points are on
single router.
Only applicable when two exit points are on
single router.
4.
Never advertise out from router and will remain
local to router.
Never advertise out from router and will remain
local to router.
5.
Higher is preferred
Higher is preferred
6.
Range is 0 – 65535.
Range is 0 – 65535.
7.
When using Route-map to manipulate weight then
it cannot be applied in Outgoing direction as shown below. It has to be in inbound direction.
When using Route-map to manipulate weight then
it cannot be applied in Outgoing direction as shown below. It has to be in inbound direction.
R1(config-router)#neighbor 13.13.13.3 route-map SET_WEIGHT out
% “SET_WEIGHT” used as BGP outbound route-map, set weight not supported
In below configuration example, R1 is having two paths to
reach to 20.1.1.x subnet and best path is from R2 i.e. 12.12.12.2. We want to
change the outgoing traffic from R1 to R3 by increasing the weight of R3 neighbor
but remember it will not manipulate the incoming traffic. It will change the
outgoing traffic directions only,
reach to 20.1.1.x subnet and best path is from R2 i.e. 12.12.12.2. We want to
change the outgoing traffic from R1 to R3 by increasing the weight of R3 neighbor
but remember it will not manipulate the incoming traffic. It will change the
outgoing traffic directions only,
Weight will change the path for 20.1.1.x from R2 to R3.
R1:-
interface Loopback0
ip address 1.1.1.1
255.255.255.255
255.255.255.255
interface FastEthernet0/0
description ”
Connected to R2″
Connected to R2″
ip address
12.12.12.1 255.255.255.0
12.12.12.1 255.255.255.0
no shut
interface FastEthernet0/1
description ”
Connected to R3″
Connected to R3″
ip address
13.13.13.1 255.255.255.0
13.13.13.1 255.255.255.0
no shut
interface FastEthernet2/0
description ”
Connected to PC1″
Connected to PC1″
ip address
10.1.1.1 255.255.255.0
10.1.1.1 255.255.255.0
no shut
router bgp 1
no synchronization
bgp
log-neighbor-changes
log-neighbor-changes
network 10.1.1.0
mask 255.255.255.0
mask 255.255.255.0
neighbor 12.12.12.2
remote-as 1
remote-as 1
neighbor
13.13.13.3 remote-as 1
13.13.13.3 remote-as 1
Without Weight configured.
R1#sh ip bgp
BGP table version is 3, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid,
> best, i – internal,
> best, i – internal,
r
RIB-failure, S Stale, m multipath, b backup-path, x best-external
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
*> 10.1.1.0/24
0.0.0.0 0 32768 i
0.0.0.0 0 32768 i
* i20.1.1.0/24
13.13.13.3 0 100
0 2 i
13.13.13.3 0 100
0 2 i
*>i 12.12.12.2 0 100
0 2 I \Route
Via R2 is preferred without weight
0 2 I \Route
Via R2 is preferred without weight
With Weight configured.
Weight can be set using any of the below methods:-
Option A:-
router bgp 1
neighbor 13.13.13.3 weight 100
OR
Option B:- It is more flexible as in here we can apply
weight on specific routes as well by calling an Prefix-list or access-list that
matches the routes under Route map.
weight on specific routes as well by calling an Prefix-list or access-list that
matches the routes under Route map.
router bgp 1
neighbor 13.13.13.3 route-map SET_WEIGHT in
route-map
SET_WEIGHT
SET_WEIGHT
set weight 100
R1#sh ip bgp
BGP table version is 4, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid,
> best, i – internal,
> best, i – internal,
r
RIB-failure, S Stale, m multipath, b backup-path, x best-external
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
*> 10.1.1.0/24
0.0.0.0 0 32768 i
0.0.0.0 0 32768 i
*>i20.1.1.0/24 13.13.13.3 0
100 100 2 I \Above configured weight has changed the path
100 100 2 I \Above configured weight has changed the path
* i
12.12.12.2 0 100
0 2 i
12.12.12.2 0 100
0 2 i
R2:-
interface Loopback0
ip address 2.2.2.2
255.255.255.255
255.255.255.255
interface FastEthernet0/0
description ”
Connected to R1″
Connected to R1″
ip address
12.12.12.2 255.255.255.0
12.12.12.2 255.255.255.0
no shut
interface FastEthernet1/0
description ”
Connected to R5″
Connected to R5″
ip address
25.25.25.2 255.255.255.0
25.25.25.2 255.255.255.0
no shut
router bgp 1
no synchronization
bgp router-id
2.2.2.2
2.2.2.2
bgp
log-neighbor-changes
log-neighbor-changes
neighbor
12.12.12.1 remote-as 1
12.12.12.1 remote-as 1
neighbor
12.12.12.1 next-hop-self
12.12.12.1 next-hop-self
neighbor
25.25.25.5 remote-as 2
25.25.25.5 remote-as 2
R3:-
interface Loopback0
ip address 3.3.3.3
255.255.255.255
255.255.255.255
interface FastEthernet0/1
description ” Connected to R1″
ip address
13.13.13.3 255.255.255.0
13.13.13.3 255.255.255.0
no shut
interface FastEthernet1/0
description ” Connected to R4″
ip address
34.34.34.3 255.255.255.0
34.34.34.3 255.255.255.0
no shut
router bgp 1
no synchronization
bgp router-id
3.3.3.3
3.3.3.3
bgp
log-neighbor-changes
log-neighbor-changes
neighbor
13.13.13.1 remote-as 1
13.13.13.1 remote-as 1
neighbor
13.13.13.1 next-hop-self
13.13.13.1 next-hop-self
neighbor
34.34.34.4 remote-as 2
34.34.34.4 remote-as 2
no auto-summary
!
R4:-
interface FastEthernet0/1
description ” Connected to R6″
ip address
46.46.46.4 255.255.255.0
46.46.46.4 255.255.255.0
no shut
interface FastEthernet1/0
description ” Connected to R3″
ip address
34.34.34.4 255.255.255.0
34.34.34.4 255.255.255.0
no shut
router bgp 2
no synchronization
bgp
log-neighbor-changes
log-neighbor-changes
neighbor
34.34.34.3 remote-as 1
34.34.34.3 remote-as 1
neighbor
46.46.46.6 remote-as 2
46.46.46.6 remote-as 2
neighbor
46.46.46.6 next-hop-self
46.46.46.6 next-hop-self
no auto-summary
!
R5:-
interface Loopback0
ip address 5.5.5.5
255.255.255.255
255.255.255.255
interface FastEthernet0/0
description ” Connected to R6″
ip address
56.56.56.5 255.255.255.0
56.56.56.5 255.255.255.0
no shut
interface FastEthernet1/0
description ” Connected to R2″
ip address
25.25.25.5 255.255.255.0
25.25.25.5 255.255.255.0
no shut
router bgp 2
no synchronization
bgp
log-neighbor-changes
log-neighbor-changes
neighbor
25.25.25.2 remote-as 1
25.25.25.2 remote-as 1
neighbor
56.56.56.6 remote-as 2
56.56.56.6 remote-as 2
neighbor
56.56.56.6 next-hop-self
56.56.56.6 next-hop-self
no auto-summary
R6:-
interface Loopback0
ip address 6.6.6.6
255.255.255.255
255.255.255.255
interface FastEthernet0/0
description ” Connected to R5″
ip address
56.56.56.6 255.255.255.0
56.56.56.6 255.255.255.0
no shut
interface FastEthernet0/1
description ” Connected to R4″
ip address
46.46.46.6 255.255.255.0
46.46.46.6 255.255.255.0
no shut
interface FastEthernet2/0
description ” Connected to PC2″
ip address
20.1.1.1 255.255.255.0
20.1.1.1 255.255.255.0
no shut
router bgp 2
no synchronization
bgp
log-neighbor-changes
log-neighbor-changes
network 20.1.1.0
mask 255.255.255.0
mask 255.255.255.0
neighbor
46.46.46.4 remote-as 2
46.46.46.4 remote-as 2
neighbor
56.56.56.5 remote-as 2
56.56.56.5 remote-as 2
no auto-summary
PC1:-
PC1> show ip
NAME :
PC1[1]
PC1[1]
IP/MASK :
10.1.1.10/24
10.1.1.10/24
GATEWAY :
10.1.1.1
10.1.1.1
DNS :
MAC : 00:50:79:66:68:00
LPORT : 10003
RHOST:PORT :
127.0.0.1:10002
127.0.0.1:10002
MTU: : 1500
PC2:-
PC2> show ip
NAME :
PC2[1]
PC2[1]
IP/MASK :
20.1.1.10/24
20.1.1.10/24
GATEWAY :
20.1.1.1
20.1.1.1
DNS :
MAC :
00:50:79:66:68:00
00:50:79:66:68:00
LPORT : 10003
RHOST:PORT :
127.0.0.1:10002
127.0.0.1:10002
MTU: : 1500
Verification:-
R2:-
R2#sh ip bgp summ
BGP router identifier 2.2.2.2, local AS number 1
BGP table version is 3, main routing table version 3
2 network entries using 256 bytes of memory
2 path entries using 104 bytes of memory
2/2 BGP path/bestpath attribute entries using 248 bytes
of memory
of memory
1 BGP AS-PATH 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 632 total bytes of memory
BGP activity 2/0 prefixes, 2/0 paths, scan interval 60
secs
secs
Neighbor
V AS MsgRcvd
MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
V AS MsgRcvd
MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.12.12.1
4 1 316
317 3 0
0 04:41:15 1
4 1 316
317 3 0
0 04:41:15 1
25.25.25.5
4 2 312
313 3 0
0 04:41:10 1
4 2 312
313 3 0
0 04:41:10 1
R2#sh ip bgp
BGP table version is 3, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid,
> best, i – internal,
> best, i – internal,
r
RIB-failure, S Stale, m multipath, b backup-path, x best-external
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
*>i10.1.1.0/24
12.12.12.1 0 100
0 i
12.12.12.1 0 100
0 i
*> 20.1.1.0/24
25.25.25.5
0 2 i
25.25.25.5
0 2 i
R3:-
R3#sh ip bgp summ
BGP router identifier 3.3.3.3, local AS number 1
BGP table version is 3, main routing table version 3
2 network entries using 256 bytes of memory
2 path entries using 104 bytes of memory
2/2 BGP path/bestpath attribute entries using 248 bytes
of memory
of memory
1 BGP AS-PATH 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 632 total bytes of memory
BGP activity 2/0 prefixes, 2/0 paths, scan interval 60
secs
secs
Neighbor
V AS MsgRcvd
MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
V AS MsgRcvd
MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
13.13.13.1
4 1 318
314 3 0
0 04:41:25 1
4 1 318
314 3 0
0 04:41:25 1
34.34.34.4
4 2 312
316 3 0
0 04:41:21 1
4 2 312
316 3 0
0 04:41:21 1
R3#sh ip bgp
BGP table version is 3, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid,
> best, i – internal,
> best, i – internal,
r
RIB-failure, S Stale, m multipath, b backup-path, x best-external
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
*>i10.1.1.0/24
13.13.13.1 0 100
0 i
13.13.13.1 0 100
0 i
*> 20.1.1.0/24
34.34.34.4
0 2 i
34.34.34.4
0 2 i
R4:-
R4#sh ip bgp summ
BGP router identifier 4.4.4.4, local AS number 2
BGP table version is 4, main routing table version 4
2 network entries using 256 bytes of memory
2 path entries using 104 bytes of memory
2/2 BGP path/bestpath attribute entries using 248 bytes
of memory
of memory
1 BGP AS-PATH 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 632 total bytes of memory
BGP activity 2/0 prefixes, 2/0 paths, scan interval 60
secs
secs
Neighbor
V AS MsgRcvd
MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
V AS MsgRcvd
MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
34.34.34.3
4 1 323
319 4 0
0 04:47:19 1
4 1 323
319 4 0
0 04:47:19 1
46.46.46.6
4 2 321
320 4 0
0 04:47:20 1
4 2 321
320 4 0
0 04:47:20 1
R4#sh ip bgp
BGP table version is 4, local router ID is 4.4.4.4
Status codes: s suppressed, d damped, h history, * valid,
> best, i – internal,
> best, i – internal,
r
RIB-failure, S Stale, m multipath, b backup-path, x best-external
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
*> 10.1.1.0/24
34.34.34.3
0 1 i
34.34.34.3
0 1 i
*>i20.1.1.0/24
46.46.46.6 0 100
0 i
46.46.46.6 0 100
0 i
R4#
R5:-
R5#sh ip bgp summ
BGP router identifier 5.5.5.5, local AS number 2
BGP table version is 3, main routing table version 3
2 network entries using 256 bytes of memory
2 path entries using 104 bytes of memory
2/2 BGP path/bestpath attribute entries using 248 bytes
of memory
of memory
1 BGP AS-PATH 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 632 total bytes of memory
BGP activity 2/0 prefixes, 2/0 paths, scan interval 60
secs
secs
Neighbor
V AS MsgRcvd MsgSent TblVer
InQ OutQ Up/Down State/PfxRcd
V AS MsgRcvd MsgSent TblVer
InQ OutQ Up/Down State/PfxRcd
25.25.25.2
4 1 321
320 3 0
0 04:47:42 1
4 1 321
320 3 0
0 04:47:42 1
56.56.56.6
4 2 319
320 3 0
0 04:47:43 1
4 2 319
320 3 0
0 04:47:43 1
R5#sh ip bgp
BGP table version is 3, local router ID is 5.5.5.5
Status codes: s suppressed, d damped, h history, * valid,
> best, i – internal,
> best, i – internal,
r
RIB-failure, S Stale, m multipath, b backup-path, x best-external
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
*> 10.1.1.0/24
25.25.25.2
0 1 i
25.25.25.2
0 1 i
*>i20.1.1.0/24
56.56.56.6 0 100
0 i
56.56.56.6 0 100
0 i
R5#
R6:-
R6#sh ip bgp summ
BGP router identifier 6.6.6.6, local AS number 2
BGP table version is 4, main routing table version 4
2 network entries using 256 bytes of memory
3 path entries using 156 bytes of memory
2/2 BGP path/bestpath attribute entries using 248 bytes
of memory
of memory
1 BGP AS-PATH 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 684 total bytes of memory
BGP activity 2/0 prefixes, 3/0 paths, scan interval 60
secs
secs
Neighbor
V AS MsgRcvd
MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
V AS MsgRcvd
MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
46.46.46.4
4 2 321
322 4 0
0 04:48:27 1
4 2 321
322 4 0
0 04:48:27 1
56.56.56.5
4 2 320
319 4 0
0 04:48:28 1
4 2 320
319 4 0
0 04:48:28 1
R6#sh ip bgp
BGP table version is 4, local router ID is 6.6.6.6
Status codes: s suppressed, d damped, h history, * valid,
> best, i – internal,
> best, i – internal,
r
RIB-failure, S Stale, m multipath, b backup-path, x best-external
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
*>i10.1.1.0/24
46.46.46.4 0 100
0 1 i
46.46.46.4 0 100
0 1 i
* i
56.56.56.5 0 100
0 1 i
56.56.56.5 0 100
0 1 i
*> 20.1.1.0/24
0.0.0.0 0 32768 i
0.0.0.0 0 32768 i
R6#
PC1:-
PC1> trace 20.1.1.10
trace to 20.1.1.10, 8 hops max, press Ctrl+C to stop
1 10.1.1.1
40.000 ms 10.000 ms 10.000 ms
40.000 ms 10.000 ms 10.000 ms
2 13.13.13.3
30.000 ms 30.000 ms 30.000 ms
30.000 ms 30.000 ms 30.000 ms
3 34.34.34.4
50.000 ms 50.000 ms 50.000 ms
50.000 ms 50.000 ms 50.000 ms
4 46.46.46.6
90.000 ms 80.000 ms 70.000 ms
90.000 ms 80.000 ms 70.000 ms
5 *20.1.1.10
150.000 ms (ICMP type:3, code:3, Destination port unreachable)
150.000 ms (ICMP type:3, code:3, Destination port unreachable)
PC2:-
PC2> trace 10.1.1.10
trace to 10.1.1.10, 8 hops max, press Ctrl+C to stop
1 20.1.1.1
10.000 ms 10.000 ms 10.000 ms
10.000 ms 10.000 ms 10.000 ms
2 46.46.46.4
30.000 ms 30.000 ms 30.000 ms
30.000 ms 30.000 ms 30.000 ms
3 34.34.34.3
40.000 ms 50.000 ms 50.000 ms
40.000 ms 50.000 ms 50.000 ms
4 13.13.13.1
60.000 ms 60.000 ms 60.000 ms
60.000 ms 60.000 ms 60.000 ms
5 *10.1.1.10
70.000 ms (ICMP type:3, code:3, Destination port unreachable)
70.000 ms (ICMP type:3, code:3, Destination port unreachable)