Case 1...
Config in R3
router bgp 101
bgp log-neighbor-changes
network 33.0.0.0
neighbor 1.1.1.1 remote-as 101
neighbor 1.1.1.1 update-source Loopback0
..........
R3#
No auto-summary is configured so BGP will require exact Network mask which is present in the routing table.
So in this case 33.0.0.0/8 will not be advertise in the BGP update.
R1#sh ip bgp
BGP table version is 21,
local router ID is 1.1.1.1
!!!!!!!
Network Next Hop Metric LocPrf Weight Path
* i 4.4.4.4/32 4.4.4.4
0 100
0 201 i
* i 44.4.4.4/32 4.4.4.4 0 100
0 201 i
*>i 55.5.5.5/32 5.5.5.5 0 100
0 i
* i 66.6.6.6/32 6.6.6.6 0 100
0 1.301 i
*>
6.6.6.6 0 0 1.301 i
R1#
Now Auto-summary will be configured.
Config in R3....
R3#sh run | sec bgp
router bgp 101
bgp log-neighbor-changes
network 33.0.0.0
neighbor 1.1.1.1 remote-as 101
neighbor 1.1.1.1 update-source Loopback0
............
auto-summary
Network 33.0.0.0/8 classfull
advertised . Auto-summary will do
this .
see in R1
R1#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
* i 4.4.4.4/32 4.4.4.4 0 100
0 201 i
*>i 33.0.0.0 3.3.3.3 0 100
0 i Classful network for 33.0.0.0/8 will be advertised.
* i 44.4.4.4/32 4.4.4.4 0 100
0 201 i
*>i 55.5.5.5/32 5.5.5.5 0 100
0 i
*>
66.6.6.6/32 6.6.6.6 0 0 1.301 i
* i 6.6.6.6 0 100
0 1.301 i
R1#
Case 2
if any individual network is advertised , in Auto-summary case it will be advertised too.
R3(config)#router bgp 101
R3(config-router)#net 39.1.1.0 mask 255.255.255.0
Sh ip bgp
*>i 39.0.0.0 3.3.3.3 0 100 0 ?
*>i 39.1.1.0/24 3.3.3.3 0 100 0 i
No comments:
Post a Comment