01-26-2015 08:26 PM - edited 03-01-2019 02:51 PM
Dear All
Good morning everyone!
Need your assistant to solve this problem as below:
Description: There are four AS in this diagram. Assume that we’re in AS30. AS40 and AS50 are our upstream and AS10 is our downstream. There are two routers in AS10 using iBGP. And each router in that AS10 is connected to R3 at AS30.
In R3 currentlly, all traffic destinate to R1 will be via R1, and all destination to R2 wil be via R2.
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 192.168.31.1 0 0 10 i
* 192.168.32.2 2 0 10 i
*> 1.1.2.0/24 192.168.31.1 0 0 10 i
* 192.168.32.2 2 0 10 i
*> 1.1.3.0/24 192.168.31.1 0 0 10 i
* 192.168.32.2 2 0 10 i
* 2.2.1.0/24 192.168.31.1 2 0 10 i
*> 192.168.32.2 0 0 10 i
* 2.2.2.0/24 192.168.31.1 2 0 10 i
*> 192.168.32.2 0 0 10 i
*> 4.4.4.4/32 192.168.34.4 0 0 40 i
*> 5.5.5.5/32 192.168.35.5 0 0 50 i
R4#traceroute 1.1.1.1 source 4.4.4.4
Type escape sequence to abort.
Tracing the route to 1.1.1.1
1 192.168.34.3 100 msec 12 msec 92 msec
2 192.168.31.1 96 msec 132 msec 88 msec
R4#traceroute 2.2.2.2 source 4.4.4.4
Type escape sequence to abort.
Tracing the route to 2.2.2.2
1 192.168.34.3 96 msec 56 msec 72 msec
2 192.168.32.2 128 msec 48 msec 92 msec
R5#traceroute 2.2.2.2 source 5.5.5.5
Type escape sequence to abort.
Tracing the route to 2.2.2.2
1 192.168.35.3 104 msec 96 msec 80 msec
2 192.168.32.2 92 msec 76 msec 64 msec
R5#traceroute 1.1.1.1 source 5.5.5.5
Type escape sequence to abort.
Tracing the route to 1.1.1.1
1 192.168.35.3 96 msec 88 msec 164 msec
2 192.168.31.1 112 msec 88 msec 32 msec
Objective:
I've used route-map to set next hob IP to match my objectives and the result is fine.
I would like to ask if there is another method besides this policy based routing to archive it.
Your comment would be much appreciated.
01-27-2015 05:18 AM
I'm not sure whether this will work or not, haven't try it myself.
but try to use as-prepend and apply the route-map to desired BGP neighbor.
Please inform me whether this work or not
access-list 1 permit 1.1.0.0 0.0.255.255
access-list 2 permit 2.2.0.0 0.0.255.255
!
route-map AS40AS10 permit 10
match ip address 2
set as-path prepend 30 30 30 30
!
route-map AS40AS10 permit 20
match ip address 1
!
route-map AS50AS10 permit 10
match ip address 1
set as-path prepend 30 30 30 30
!
route-map AS50AS10 permit 20
match ip address 2
!
router bgp 30
neighbor 4.4.4.4 route-map AS40AS10 out
neighbor 5.5.5.5 route-map AS50AS10 out
!
R4 will have path like 0 30 30 30 30 30 to reach R2 network and,
R5 will have path 0 30 30 30 30 30 to reach R1 network. If not, try clear ip bgp proc on R4 & R5
i hope it works
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