3

What does Local mean in this output?

R4#show ip bgp 10.6.0.0/24  
BGP routing table entry for 10.6.0.0/24, version 19  
Paths: (1 available, best #1, table Default-IP-Routing-Table)  
  Advertised to update-groups:  
        2  
  **Local**    192.168.0.6 (metric 156160) from 192.168.0.5 (192.168.0.5)  
      Origin IGP, metric 0, localpref 100, valid, internal, best  
      Originator: 192.168.0.6, Cluster list: 192.168.0.5
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6

The Local keyword highlighted in your question means the prefix is sourced locally in that router's AS (i.e. there is no AS path).

Consider two configurations, where the routers have a BGP session with each other, and DEN-EDGE-01 is announcing 10.204.1.1/32. 

Announce:10.204.1.1/32
DEN-EDGE-01----------------DEN-EDGE-02
172.16.1.203               172.16.1.204

Peering within the same ASN: Local keyword shown

DEN-EDGE-01 in AS100 is configured to send 10.204.1.1...

router bgp 100
 no synchronization
 bgp log-neighbor-changes
 network 10.204.1.1 mask 255.255.255.255
 ! Send 10.204.1.1 to DEN-EDGE-02
 neighbor 172.16.2.204 remote-as 100
 no auto-summary

DEN-EDGE-02 in AS100 is configured with...

router bgp 100
 no synchronization
 bgp log-neighbor-changes
 ! Just receive routes from DEN-EDGE-01
 neighbor 172.16.2.203 remote-as 100
 no auto-summary
!

When I receive 10.204.1.1 on DEN-EDGE-02, there is no AS-path, only Local

DEN-EDGE-02#sh ip bgp 10.204.1.1
BGP routing table entry for 10.204.1.1/32, version 2
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Flag: 0x820
  Not advertised to any peer
  Local   <------------
    172.16.2.203 from 172.16.2.203 (172.16.2.203)
      Origin IGP, metric 0, localpref 100, valid, internal, best
DEN-EDGE-02#

Peering with a different ASN: AS path shown

Now we reconfigure both routers... one in AS100 and the other in AS200. DEN-EDGE-01 in AS100 is configured to send 10.204.1.1...

router bgp 100
 no synchronization
 bgp log-neighbor-changes
 network 10.204.1.1 mask 255.255.255.255
 ! Send 10.204.1.1 to DEN-EDGE-02
 neighbor 172.16.2.204 remote-as 200
 no auto-summary

DEN-EDGE-02 in AS200 is configured with...

router bgp 200
 no synchronization
 bgp log-neighbor-changes
 ! Just receive routes from DEN-EDGE-01
 neighbor 172.16.2.203 remote-as 100
 no auto-summary
!

When I receive 10.204.1.1 on DEN-EDGE-02, now we see a real AS-path, because DEN-EDGE-01 is in a different AS.

DEN-EDGE-02#sh ip bgp 10.204.1.1
BGP routing table entry for 10.204.1.1/32, version 2
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Flag: 0x820
  Not advertised to any peer
  100   <------------
    172.16.2.203 from 172.16.2.203 (172.16.2.203)
      Origin IGP, metric 0, localpref 100, valid, external, best
DEN-EDGE-02#
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