Origin Attribute
The origin is a mandatory attribute that defines the origin of the path information. The origin attribute can assume three values:
IGP: Network Layer Reachability Information (NLRI) is interior to the originating AS. This normally happens when we use the bgp network command or when IGP is redistributed into BGP, then the origin of the path info will be IGP. This is indicated with an "i" in the BGP table.
EGP: NLRI is learned via EGP (Exterior Gateway Protocol). This is indicated with an "e" in the BGP table.
INCOMPLETE: NLRI is unknown or learned via some other means. This usually occurs when we redistribute a static route into BGP and the origin of the route will be incomplete. This is indicated with an "?" in the BGP table.
RTA will reach 170.10.0.0 via: 300 i (which means the next AS path is 300 and the origin of the route is IGP).The origin is a mandatory attribute that defines the origin of the path information. The origin attribute can assume three values:
IGP: Network Layer Reachability Information (NLRI) is interior to the originating AS. This normally happens when we use the bgp network command or when IGP is redistributed into BGP, then the origin of the path info will be IGP. This is indicated with an "i" in the BGP table.
EGP: NLRI is learned via EGP (Exterior Gateway Protocol). This is indicated with an "e" in the BGP table.
INCOMPLETE: NLRI is unknown or learned via some other means. This usually occurs when we redistribute a static route into BGP and the origin of the route will be incomplete. This is indicated with an "?" in the BGP table.
RTA#
router bgp 100
neighbor 190.10.50.1 remote−as 100
neighbor 170.10.20.2 remote−as 300
network 150.10.0.0
redistribute static
ip route 190.10.0.0 255.255.0.0 null0
RTB#
router bgp 100
neighbor 150.10.30.1 remote−as 100
network 190.10.50.0
RTE#
router bgp 300
neighbor 170.10.20.1 remote−as 100
network 170.10.0.0
RTA will also reach 190.10.50.0 via: i (which means, the entry is in the same AS and the origin is IGP).
RTE will reach 150.10.0.0 via: 100 i (the next AS is 100 and the origin is IGP).
RTE will also reach 190.10.0.0 via: 100 ? (the next AS is 100 and the origin is incomplete "?", coming from a static route).
2 Comments:
All redistributed routes are (?) no matter what type of route was redistributed. If a static route was redistributed or if an IGP was redistributed, the origin for both is a (?). The network command and the network command only will be an (i). You don't really see (e) anymore.
There are many mistakes in particular lab, first of all you are required to apply IGP on R1, R2 and R3 otherwise blackhole is created and networks will be unreachable.
Moreover, there is not a requirement to put static route of 190 network at R1 as that can be learn through IGP but need to advertise 170 so that R3 can learn it through IGP. Also, need to define next-hop-self for iBGP peer at R1 otherwise next hope won't be updated.
R1#sh run | begin router
router ospf 1
log-adjacency-changes
network 150.10.30.0 0.0.0.255 area 0
!
router bgp 100
no synchronization
bgp log-neighbor-changes
network 170.10.20.0 mask 255.255.255.0
neighbor 170.10.20.4 remote-as 300
neighbor 175.10.40.3 remote-as 100
neighbor 175.10.40.3 next-hop-self
no auto-summary
R2#router ospf 1
log-adjacency-changes
network 150.10.30.0 0.0.0.255 area 0
network 175.10.40.0 0.0.0.255 area 0
R3#sh run | begin router
router ospf 1
log-adjacency-changes
network 175.10.40.0 0.0.0.255 area 0
network 190.10.50.0 0.0.0.255 area 0
!
router bgp 100
no synchronization
bgp log-neighbor-changes
network 190.10.50.0 mask 255.255.255.0
neighbor 150.10.30.1 remote-as 100
no auto-summary
R4#sh run | begin router
router bgp 300
no synchronization
bgp log-neighbor-changes
network 170.10.0.0 mask 255.255.255.0
neighbor 170.10.20.1 remote-as 100
no auto-summary
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