[Cisco] Unequal load-sharing w/ BGP dmz-link

Unequal load-sharing w/ BGP dmz-link

+------ bw 1024k ----[R2]--------->[R4]
|
[R1]
|
+------ bw 512k -----[R3]--------->[R4]

BGP routing
R1 ---> AS1
R2,R3,R4 ---> AS234

OSPF routing
R2,R3,R4 area 0

R1 --> R2 = 1024k
R1 --> R3 = 512k

R4 load share between R2 and R3
!===================================================
[R1 Configuration]
interface Serial2/0.12 point-to-point
des ** Connect to R2 **
bandwidth 1024
ip address 160.1.12.1 255.255.255.0
frame-relay interface-dlci 102
!
interface Serial2/0.13 point-to-point
des ** Connect to R3 **
bandwidth 512
ip address 160.1.13.1 255.255.255.0
frame-relay interface-dlci 103
!
router bgp 1
bgp log-neighbor-changes
neighbor 160.1.12.2 remote-as 234
neighbor 160.1.13.3 remote-as 234
!
address-family ipv4
neighbor 160.1.12.2 activate
neighbor 160.1.13.3 activate
no auto-summary
no synchronization
network 10.1.1.0 mask 255.255.255.0
exit-address-family
!
!====================================================
[R2 Configuration]
interface Serial2/0.12 point-to-point
des ** Connect to R1 **
bandwidth 1024
ip address 160.1.12.2 255.255.255.0
frame-relay interface-dlci 201
!
interface Serial2/0.24 point-to-point
des ** Connect to R4 **
ip address 160.1.24.2 255.255.255.0
frame-relay interface-dlci 204
!
router ospf 1
log-adjacency-changes
network 0.0.0.0 255.255.255.255 area 0
!
router bgp 234
bgp log-neighbor-changes
neighbor 160.1.12.1 remote-as 1
neighbor 160.1.24.4 remote-as 234
!
address-family ipv4
neighbor 160.1.12.1 activate
neighbor 160.1.12.1 default-originate
neighbor 160.1.12.1 dmzlink-bw
neighbor 160.1.24.4 activate
neighbor 160.1.24.4 next-hop-self
neighbor 160.1.24.4 send-community both
no auto-summary
no synchronization
bgp dmzlink-bw
exit-address-family
!
!====================================================
[R3 Configuration]

interface Serial1/0.13 point-to-point
des ** Connect to R1 **
bandwidth 512
ip address 160.1.13.3 255.255.255.0
frame-relay interface-dlci 301
!
interface Serial1/0.34 point-to-point
des ** Connect to R4 **
ip address 160.1.34.3 255.255.255.0
frame-relay interface-dlci 304
!
router ospf 1
log-adjacency-changes
network 0.0.0.0 255.255.255.255 area 0
!
router bgp 234
bgp log-neighbor-changes
neighbor 160.1.13.1 remote-as 1
neighbor 160.1.34.4 remote-as 234
!
address-family ipv4
neighbor 160.1.13.1 activate
neighbor 160.1.13.1 default-originate
neighbor 160.1.13.1 dmzlink-bw
neighbor 160.1.34.4 activate
neighbor 160.1.34.4 send-community both
neighbor 160.1.34.4 next-hop-self
no auto-summary
no synchronization
bgp dmzlink-bw
exit-address-family
!
!====================================================
[R4 Configuration]
interface Serial1/0.24 point-to-point
des ** Connect to R2 **
ip address 160.1.24.4 255.255.255.0
frame-relay interface-dlci 402
!
interface Serial1/0.34 point-to-point
des ** Connect to R3 **
ip address 160.1.34.4 255.255.255.0
frame-relay interface-dlci 403
!
router bgp 234
bgp log-neighbor-changes
neighbor 160.1.24.2 remote-as 234
neighbor 160.1.34.3 remote-as 234
maximum-paths ibgp 2
!
address-family ipv4
neighbor 160.1.24.2 activate
neighbor 160.1.24.2 send-community both
neighbor 160.1.24.2 route-reflector-client
neighbor 160.1.34.3 activate
neighbor 160.1.34.3 send-community both
neighbor 160.1.34.3 route-reflector-client
maximum-paths ibgp 2
no auto-summary
no synchronization
bgp dmzlink-bw
exit-address-family
!
!====================================================

[R2]
R2#sh ip bgp 10.1.1.0
BGP routing table entry for 10.1.1.0/24, version 6
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Advertised to update-groups:
2
1
160.1.12.1 from 160.1.12.1 (10.1.11.1)
Origin IGP, metric 0, localpref 100, valid, external, best
DMZ-Link Bw 128 kbytes
R2#sh ip route 10.1.1.0
Routing entry for 10.1.1.0/24
Known via "bgp 234", distance 20, metric 0
Tag 1, type external
Last update from 160.1.12.1 01:06:53 ago
Routing Descriptor Blocks:
* 160.1.12.1, from 160.1.12.1, 01:06:53 ago
Route metric is 0, traffic share count is 1
AS Hops 1
Route tag 1


[R3]
R3#sh ip bgp 10.1.1.0
BGP routing table entry for 10.1.1.0/24, version 7
Paths: (2 available, best #2, table Default-IP-Routing-Table)
Advertised to update-groups:
2
1
160.1.24.2 (metric 128) from 160.1.34.4 (10.1.44.4)
Origin IGP, metric 0, localpref 100, valid, internal
Originator: 10.1.22.2, Cluster list: 10.1.44.4
1
160.1.13.1 from 160.1.13.1 (10.1.11.1)
Origin IGP, metric 0, localpref 100, valid, external, best
DMZ-Link Bw 64 kbytes
R3#sh ip route 10.1.1.0
Routing entry for 10.1.1.0/24
Known via "bgp 234", distance 20, metric 0
Tag 1, type external
Last update from 160.1.13.1 01:18:28 ago
Routing Descriptor Blocks:
* 160.1.13.1, from 160.1.13.1, 01:18:28 ago
Route metric is 0, traffic share count is 1
AS Hops 1
Route tag 1


[R4]
R4#sh ip bgp 10.1.1.0
BGP routing table entry for 10.1.1.0/24, version 8
Paths: (2 available, best #1, table Default-IP-Routing-Table)
Multipath: iBGP
Advertised to update-groups:
1
1, (Received from a RR-client)
160.1.24.2 from 160.1.24.2 (10.1.22.2)
Origin IGP, metric 0, localpref 100, valid, internal, multipath, best
DMZ-Link Bw 128 kbytes
1, (Received from a RR-client)
160.1.34.3 from 160.1.34.3 (10.1.33.3)
Origin IGP, metric 0, localpref 100, valid, internal, multipath
DMZ-Link Bw 64 kbytes
R4#sh ip route 10.1.1.0
Routing entry for 10.1.1.0/24
Known via "bgp 234", distance 200, metric 0
Tag 1, type internal
Last update from 160.1.34.3 00:07:48 ago
Routing Descriptor Blocks:
160.1.34.3, from 160.1.34.3, 00:07:48 ago
Route metric is 0, traffic share count is 19
AS Hops 1
Route tag 1
* 160.1.24.2, from 160.1.24.2, 00:07:48 ago
Route metric is 0, traffic share count is 40
AS Hops 1
Route tag 1

R4#sh ip cef 10.1.1.0 internal
10.1.1.0/24, version 35, epoch 0, per-packet sharing
0 packets, 0 bytes
via 160.1.34.3, 0 dependencies, recursive
traffic share 19, current path
next hop 160.1.34.3, Serial1/0.34 via 160.1.34.0/24
valid adjacency
via 160.1.24.2, 0 dependencies, recursive
traffic share 40
next hop 160.1.24.2, Serial1/0.24 via 160.1.24.0/24
valid adjacency

0 packets, 0 bytes switched through the prefix
tmstats: external 0 packets, 0 bytes
internal 0 packets, 0 bytes
Load distribution: 0 1 0 1 0 1 0 1 0 1 1 1 1 1 1 1 (refcount 1)

Hash OK Interface Address Packets
1 Y Serial1/0.34 point2point 0
2 Y Serial1/0.24 point2point 0
3 Y Serial1/0.34 point2point 0
4 Y Serial1/0.24 point2point 0
5 Y Serial1/0.34 point2point 0
6 Y Serial1/0.24 point2point 0
7 Y Serial1/0.34 point2point 0
8 Y Serial1/0.24 point2point 0
9 Y Serial1/0.34 point2point 0
10 Y Serial1/0.24 point2point 0
11 Y Serial1/0.24 point2point 0
12 Y Serial1/0.24 point2point 0
13 Y Serial1/0.24 point2point 0
14 Y Serial1/0.24 point2point 0
15 Y Serial1/0.24 point2point 0
16 Y Serial1/0.24 point2point 0
refcount 6
R4#