BGP ORIGIN Attribute

What Is ORIGIN?

ORIGIN (type code 1) is a well-known mandatory path attribute that shows how the route entered BGP (BGP Path Attributes and Best Path Selection). The value is one octet, set by the router that brought the route into BGP, and RFC 4271 section 5.1.1 says no other speaker should change it.

The Three Values

Value	Name	Meaning
0	`IGP`	A BGP speaker put the route into BGP explicitly, as a route interior to its own AS.
1	`EGP`	Learned from EGP (RFC 904), the predecessor of BGP. EGP is no longer used, so this never appears in practice.
2	`Incomplete`	The route entered BGP some other way. Routes injected by redistribution fall here.

In show bgp the value appears as a single character at the end of each line (i / e / ?). Inside an UPDATE it is a one-octet number (0 / 1 / 2); the character in show is that value condensed to one letter.

The i in the third column of *>i is the status code for “internal” (learned over iBGP) and has nothing to do with the i at the end of the line.

Which Operation Produces Which Value

How the route enters BGP	`ORIGIN`
Declared explicitly with `network`	`IGP` (`i`)
Generated as an aggregate with `aggregate-address`	`IGP` if every component is `IGP`. If at least one component is `Incomplete` the aggregate is `Incomplete`; if none is `Incomplete` but at least one is `EGP` it is `EGP` (RFC 4271 9.2.2.2, BGP route aggregation)
Redistributed from another protocol, a static route or a connected route	`Incomplete` (`?`)

network is the administrator declaring routes one by one, hence IGP; redistribute pours in another protocol’s routes, whose provenance BGP cannot see, hence Incomplete.

Where It Sits in Best Path Selection

ORIGIN is compared at the fifth step of best path selection, and the lower value wins (IGP < EGP < Incomplete). In practice LOCAL_PREF or AS_PATH length usually decides first, so ORIGIN matters only when everything above it is tied - for instance when the same prefix is injected at two places in the AS, once with network and once with redistribute.

Levelling ORIGIN to IGP When Advertising to eBGP

Routes originated in your own AS with network are IGP from the start. With redistribute even local routes end up as a mix of i and ?, which can affect best path selection in the neighboring AS. One way to avoid that is a route policy that levels the value to IGP on the way out to eBGP.

Rewriting ORIGIN erases the information about how the route entered BGP, and RFC 4271 section 5.1.1 says other speakers should not change it. Keep it to cases where the mix of ? actually causes trouble, and be careful not to apply it to routes received from other ASes (transit routes).

The simple form levels every route sent to that peer.

IOS XR: level ORIGIN to IGP for every route
route-policy EBGP-OUT
  set origin igp
  pass
end-policy
!
router bgp <AS number>
 neighbor <eBGP peer address>
  address-family ipv4 unicast
   route-policy EBGP-OUT out
  !
 !
!

IOS XE: level ORIGIN to IGP for every route
route-map EBGP-OUT permit 10
 set origin igp
!
router bgp <AS number>
 address-family ipv4
  neighbor <eBGP peer address> activate
  neighbor <eBGP peer address> route-map EBGP-OUT out

The pass on IOS XR and the permit 10 on IOS XE both mean “let every route through”; without them nothing is advertised at all.

This form also hits transit routes. To limit it to routes originated in your own AS, match an empty AS_PATH (^$). The local AS number is prepended after the route policy runs, so from an outbound policy’s point of view a locally originated route has an empty AS_PATH.

IOS XR: level ORIGIN only for locally originated routes
as-path-set LOCAL-ORIGIN
  ios-regex '^$'
end-set
!
route-policy EBGP-OUT
  if as-path in LOCAL-ORIGIN then
    set origin igp
  endif
  pass
end-policy

IOS XE: level ORIGIN only for locally originated routes
ip as-path access-list 1 permit ^$
!
route-map EBGP-OUT permit 10
 match as-path 1
 set origin igp
!
route-map EBGP-OUT permit 20

The empty permit 20 on IOS XE lets the non-matching routes through; without it everything that is not locally originated is dropped.

Verification on Real Devices

Six XRd 26.1.1 routers confirm (1) that ORIGIN decides the best path when everything above it is tied, and (2) what differs between rewriting every route and limiting the rewrite with ^$.

Router	AS	Role
R1	65001	Advertises `192.168.99.0/24` with `network` (`ORIGIN` is `i`); Loopback99 holds the prefix
R2	65001	Observation point. Receives R1’s `i` and R3’s `?` at the same time
R3	65001	Advertises the same `192.168.99.0/24` with `redistribute static` (`ORIGIN` is `?`). eBGP with R4
R4	65002	Receives from R3. The peer used for the outbound policy tests
R5	65003	One AS further out, to see whether the rewrite travels that far
R6	65004	Source of the transit routes: `192.168.6.0/24` via `network` (`i`) and `192.168.66.0/24` via `redistribute static` (`?`)

AS 65001 runs OSPF area 0, with a full mesh of iBGP sessions between the Loopback0s. R3’s static route points at R1’s Loopback0 (10.0.0.1) recursively, so even when R3’s path wins, traffic still reaches R1’s Loopback99.

STEP	Change	What to check
0	none (initial state)	Steps 1 to 4 are tied, so `ORIGIN` decides at step 5 (`i` wins)
1	`no network 192.168.99.0/24` on R1	The `i` route disappears and R2’s best becomes `?`; R4, R5 and R6 show `?` at the end of the line too
2	Restore `network` on R1	Back to the STEP 0 state
3	`EBGP-OUT-ALL` on R3 (`set origin igp` for every route)	Not only the local route: the transit route is rewritten to `i` as well
4	`EBGP-OUT-LOCAL` on R3 (`^$` only, final state)	Only the locally originated route becomes `i`; the transit route stays `?`

In every STEP R4 and R5 send 50 pings and a traceroute to 192.168.99.1, which also records which path carried the traffic.

STEP 0: ORIGIN Decides the Best Path

In R2’s BGP table only 192.168.99.0/24 has two lines, ending in i (from R1) and ? (from R3).

R2 show bgp (STEP 0)
RP/0/RP0/CPU0:R2#show bgp
Sun Sep 27 12:33:27.495 UTC
BGP router identifier 10.0.0.2, local AS number 65001
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000000   RD version: 11
BGP main routing table version 11
BGP NSR Initial initsync version 3 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*>i192.168.1.0/24     10.0.0.1                 0    100      0 i
*> 192.168.2.0/24     0.0.0.0                  0         32768 i
*>i192.168.3.0/24     10.0.0.3                 0    100      0 i
*>i192.168.4.0/24     10.3.4.4                 0    100      0 65002 i
*>i192.168.5.0/24     10.3.4.4                      100      0 65002 65003 i
*>i192.168.6.0/24     10.1.6.6                 0    100      0 65004 i
*>i192.168.66.0/24    10.1.6.6                 0    100      0 65004 ?
*>i192.168.99.0/24    10.0.0.1                 0    100      0 i
* i                   10.0.0.1                 0    100      0 ?

Processed 8 prefixes, 9 paths

The detailed output shows that steps 1 to 4 are all tied. The NEXT_HOP and the IGP metric are the same; the only difference is ORIGIN.

R2 show bgp 192.168.99.0/24 (STEP 0)
RP/0/RP0/CPU0:R2#show bgp 192.168.99.0/24
Sun Sep 27 12:33:28.055 UTC
BGP routing table entry for 192.168.99.0/24
Versions:
  Process           bRIB/RIB   SendTblVer
  Speaker                  8            8
Last Modified: Sep 27 12:25:36.023 for 00:07:52
Paths: (2 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    10.0.0.1 (metric 2) from 10.0.0.1 (10.0.0.1)
      Origin IGP, metric 0, localpref 100, valid, internal, best, group-best
      Received Path ID 0, Local Path ID 1, version 8
  Path #2: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    10.0.0.1 (metric 2) from 10.0.0.3 (10.0.0.3)
      Origin incomplete, metric 0, localpref 100, valid, internal
      Received Path ID 0, Local Path ID 0, version 0

Order	Criterion	Path #1 (from R1)	Path #2 (from R3)	Result
1	`WEIGHT`	0	0	tied
2	`LOCAL_PREF`	100	100	tied
3	Locally originated	both learned over iBGP	both learned over iBGP	tied
4	`AS_PATH` length	0 (originated inside the AS)	0 (originated inside the AS)	tied
5	`ORIGIN`	`IGP`	`Incomplete`	Path #1 wins

Because R3’s static route points at R1’s Loopback0, the NEXT_HOP is 10.0.0.1 on both paths. Whichever is chosen, traffic goes to the same router, R1, and the pings from R4 in AS 65002 to 192.168.99.1 get through.

R2 show route bgp (STEP 0)
RP/0/RP0/CPU0:R2#show route bgp
Sun Sep 27 12:33:27.791 UTC

B    192.168.1.0/24 [200/0] via 10.0.0.1, 00:07:52
B    192.168.3.0/24 [200/0] via 10.0.0.3, 00:08:03
B    192.168.4.0/24 [200/0] via 10.3.4.4, 00:08:03
B    192.168.5.0/24 [200/0] via 10.3.4.4, 00:08:03
B    192.168.6.0/24 [200/0] via 10.1.6.6, 00:07:51
B    192.168.66.0/24 [200/0] via 10.1.6.6, 00:07:51
B    192.168.99.0/24 [200/0] via 10.0.0.1, 00:07:52

R4 ping / traceroute 192.168.99.1 (STEP 0)
RP/0/RP0/CPU0:R4#ping 192.168.99.1 source 192.168.4.1 count 50 timeout 1
Sun Sep 27 12:34:51.497 UTC
Type escape sequence to abort.
Sending 50, 100-byte ICMP Echos to 192.168.99.1 timeout is 1 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (50/50), round-trip min/avg/max = 6/11/52 ms
RP/0/RP0/CPU0:R4#traceroute 192.168.99.1 source 192.168.4.1 probe 3 timeout 1 maxttl 6
Sun Sep 27 12:34:53.105 UTC

Type escape sequence to abort.
Tracing the route to 192.168.99.1

 1  10.3.4.3 6 msec  5 msec  4 msec 
 2  10.1.3.1 10 msec  *  10 msec 

STEP 1: Removing the `i` Route Makes the `?` Route Win

The network statement is removed from R1, which deletes the i route.

R1 removing network (STEP 1, R1 commit)
RP/0/RP0/CPU0:R1#show configuration commit changes last 1
Sun Sep 27 12:37:03.574 UTC
!! Building configuration...
!! IOS XR Configuration 26.1.1
router bgp 65001
 address-family ipv4 unicast
  no network 192.168.99.0/24
 !
!
end

R2 is left with R3’s Origin incomplete path, and in the neighboring AS 65004 (R6) the end of the line changes from i to ?.

R2 show bgp 192.168.99.0/24 (STEP 0)
RP/0/RP0/CPU0:R2#show bgp 192.168.99.0/24
Sun Sep 27 12:33:28.055 UTC
BGP routing table entry for 192.168.99.0/24
Versions:
  Process           bRIB/RIB   SendTblVer
  Speaker                  8            8
Last Modified: Sep 27 12:25:36.023 for 00:07:52
Paths: (2 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    10.0.0.1 (metric 2) from 10.0.0.1 (10.0.0.1)
      Origin IGP, metric 0, localpref 100, valid, internal, best, group-best
      Received Path ID 0, Local Path ID 1, version 8
  Path #2: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    10.0.0.1 (metric 2) from 10.0.0.3 (10.0.0.3)
      Origin incomplete, metric 0, localpref 100, valid, internal
      Received Path ID 0, Local Path ID 0, version 0

R2 show bgp 192.168.99.0/24 (STEP 1)
RP/0/RP0/CPU0:R2#show bgp 192.168.99.0/24
Sun Sep 27 12:39:55.014 UTC
BGP routing table entry for 192.168.99.0/24
Versions:
  Process           bRIB/RIB   SendTblVer
  Speaker                 12           12
Last Modified: Sep 27 12:37:39.023 for 00:02:16
Paths: (1 available, best #1)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Not advertised to any peer
  Local, (received & used)
    10.0.0.1 (metric 2) from 10.0.0.3 (10.0.0.3)
      Origin incomplete, metric 0, localpref 100, valid, internal, best, group-best
      Received Path ID 0, Local Path ID 1, version 12

R6 show bgp (STEP 0)
RP/0/RP0/CPU0:R6#show bgp
Sun Sep 27 12:36:27.824 UTC
BGP router identifier 10.0.0.6, local AS number 65004
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000000   RD version: 10
BGP main routing table version 10
BGP NSR Initial initsync version 4 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*> 192.168.1.0/24     10.1.6.1                 0             0 65001 i
*> 192.168.2.0/24     10.1.6.1                               0 65001 i
*> 192.168.3.0/24     10.1.6.1                               0 65001 i
*> 192.168.4.0/24     10.1.6.1                               0 65001 65002 i
*> 192.168.5.0/24     10.1.6.1                               0 65001 65002 65003 i
*> 192.168.6.0/24     0.0.0.0                  0         32768 i
*> 192.168.66.0/24    0.0.0.0                  0         32768 ?
*> 192.168.99.0/24    10.1.6.1                 0             0 65001 i

Processed 8 prefixes, 8 paths

R6 show bgp (STEP 1)
RP/0/RP0/CPU0:R6#show bgp
Sun Sep 27 12:42:58.136 UTC
BGP router identifier 10.0.0.6, local AS number 65004
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000000   RD version: 11
BGP main routing table version 11
BGP NSR Initial initsync version 4 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*> 192.168.1.0/24     10.1.6.1                 0             0 65001 i
*> 192.168.2.0/24     10.1.6.1                               0 65001 i
*> 192.168.3.0/24     10.1.6.1                               0 65001 i
*> 192.168.4.0/24     10.1.6.1                               0 65001 65002 i
*> 192.168.5.0/24     10.1.6.1                               0 65001 65002 65003 i
*> 192.168.6.0/24     0.0.0.0                  0         32768 i
*> 192.168.66.0/24    0.0.0.0                  0         32768 ?
*> 192.168.99.0/24    10.1.6.1                               0 65001 ?

Processed 8 prefixes, 8 paths

The capture on the R1 - R6 link shows ORIGIN as a number. No.4 in STEP 1 is INCOMPLETE (2), and No.3 after network is restored in STEP 2 is IGP (0).

STEP 1 R1 - R6 No.4 UPDATE (R1 to R6) tshark -V (excerpt)
Border Gateway Protocol - UPDATE Message
<snip>
        Path Attribute - MP_REACH_NLRI
<snip>
            Next hop: 10.1.6.1
<snip>
                192.168.99.0/24
<snip>
        Path Attribute - ORIGIN: INCOMPLETE
<snip>
            Origin: INCOMPLETE (2)
        Path Attribute - AS_PATH: 65001 
<snip>
                AS4: 65001

STEP 2 R1 - R6 No.3 UPDATE (R1 to R6) tshark -V (excerpt)
Border Gateway Protocol - UPDATE Message
<snip>
        Path Attribute - MP_REACH_NLRI
<snip>
            Next hop: 10.1.6.1
<snip>
                192.168.99.0/24
<snip>
        Path Attribute - ORIGIN: IGP
<snip>
            Origin: IGP (0)
        Path Attribute - AS_PATH: 65001 
<snip>
                AS4: 65001
        Path Attribute - MULTI_EXIT_DISC: 0

Download the pcap of the packet in the tshark output above (STEP 1 No.4, ORIGIN 2)

Download the pcap of the packet in the tshark output above (STEP 2 No.3, ORIGIN 0)

Restoring network on R1 in STEP 2 brings R2’s best path back to Origin IGP. The remaining STEPs start from that state.

STEP 3: Rewriting ORIGIN for Every Route in an Outbound Policy

A policy that sets IGP on every route is applied to the eBGP session from R3 to R4.

R3 applying EBGP-OUT-ALL (STEP 3, R3 commit)
RP/0/RP0/CPU0:R3#show configuration commit changes last 1
Sun Sep 27 12:50:01.577 UTC
!! Building configuration...
!! IOS XR Configuration 26.1.1
route-policy EBGP-OUT-ALL
  set origin igp
  pass
end-policy
!
router bgp 65001
 neighbor 10.3.4.4
  address-family ipv4 unicast
   route-policy EBGP-OUT-ALL out
  !
 !
!
end

The end of each line in what R3 advertises to R4, before (STEP 2), after (STEP 3) and once limited with ^$ (STEP 4).

R3 show bgp neighbors 10.3.4.4 advertised-routes (STEP 2)
RP/0/RP0/CPU0:R3#show bgp neighbors 10.3.4.4 advertised-routes
Sun Sep 27 12:47:10.448 UTC
Network            Next Hop        From            AS Path
192.168.1.0/24     10.3.4.3        10.0.0.1        65001i
192.168.2.0/24     10.3.4.3        10.0.0.2        65001i
192.168.3.0/24     10.3.4.3        Local           65001i
192.168.6.0/24     10.3.4.3        10.0.0.1        65001 65004i
192.168.66.0/24    10.3.4.3        10.0.0.1        65001 65004?
192.168.99.0/24    10.3.4.3        Local           65001?

Processed 6 prefixes, 6 paths

R3 show bgp neighbors 10.3.4.4 advertised-routes (STEP 3)
RP/0/RP0/CPU0:R3#show bgp neighbors 10.3.4.4 advertised-routes
Sun Sep 27 12:53:39.252 UTC
Network            Next Hop        From            AS Path
192.168.1.0/24     10.3.4.3        10.0.0.1        65001i
192.168.2.0/24     10.3.4.3        10.0.0.2        65001i
192.168.3.0/24     10.3.4.3        Local           65001i
192.168.6.0/24     10.3.4.3        10.0.0.1        65001 65004i
192.168.66.0/24    10.3.4.3        10.0.0.1        65001 65004i
192.168.99.0/24    10.3.4.3        Local           65001i

Processed 6 prefixes, 6 paths

R3 show bgp neighbors 10.3.4.4 advertised-routes (STEP 4)
RP/0/RP0/CPU0:R3#show bgp neighbors 10.3.4.4 advertised-routes
Sun Sep 27 13:00:07.773 UTC
Network            Next Hop        From            AS Path
192.168.1.0/24     10.3.4.3        10.0.0.1        65001i
192.168.2.0/24     10.3.4.3        10.0.0.2        65001i
192.168.3.0/24     10.3.4.3        Local           65001i
192.168.6.0/24     10.3.4.3        10.0.0.1        65001 65004i
192.168.66.0/24    10.3.4.3        10.0.0.1        65001 65004?
192.168.99.0/24    10.3.4.3        Local           65001i

Processed 6 prefixes, 6 paths

In STEP 3 the locally originated 192.168.99.0/24 becomes i as intended, but the transit route 192.168.66.0/24 is rewritten from ? to i as well. It looks the same from AS 65003 (R5) beyond R4.

R5 show bgp (STEP 3)
RP/0/RP0/CPU0:R5#show bgp
Sun Sep 27 12:55:11.954 UTC
BGP router identifier 10.0.0.5, local AS number 65003
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000000   RD version: 12
BGP main routing table version 12
BGP NSR Initial initsync version 3 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*> 192.168.1.0/24     10.4.5.4                               0 65002 65001 i
*> 192.168.2.0/24     10.4.5.4                               0 65002 65001 i
*> 192.168.3.0/24     10.4.5.4                               0 65002 65001 i
*> 192.168.4.0/24     10.4.5.4                 0             0 65002 i
*> 192.168.5.0/24     0.0.0.0                  0         32768 i
*> 192.168.6.0/24     10.4.5.4                               0 65002 65001 65004 i
*> 192.168.66.0/24    10.4.5.4                               0 65002 65001 65004 i
*> 192.168.99.0/24    10.4.5.4                               0 65002 65001 i

Processed 8 prefixes, 8 paths

The capture confirms it: in No.3 of STEP 3 the ORIGIN of 192.168.66.0/24 is IGP (0).

STEP 3 R3 - R4 No.3 UPDATE (R3 to R4, 192.168.66.0/24) tshark -V (excerpt)
Border Gateway Protocol - UPDATE Message
<snip>
        Path Attribute - MP_REACH_NLRI
<snip>
            Next hop: 10.3.4.3
<snip>
                192.168.66.0/24
<snip>
        Path Attribute - ORIGIN: IGP
<snip>
            Origin: IGP (0)
        Path Attribute - AS_PATH: 65001 65004 
<snip>
                AS4: 65001
                AS4: 65004

Download the pcap of the packet in the tshark output above (STEP 3 No.3, transit route at 0)

STEP 4: Levelling Only the Locally Originated Routes

Adding ^$ as a condition limits the rewrite to routes originated in this AS.

R3 applying EBGP-OUT-LOCAL (STEP 4, R3 commit)
RP/0/RP0/CPU0:R3#show configuration commit changes last 1
Sun Sep 27 12:56:30.352 UTC
!! Building configuration...
!! IOS XR Configuration 26.1.1
as-path-set LOCAL-ORIGIN
  ios-regex '^$'
end-set
!
no route-policy EBGP-OUT-ALL
route-policy EBGP-OUT-LOCAL
  if as-path in LOCAL-ORIGIN then
    set origin igp
  endif
  pass
end-policy
!
router bgp 65001
 neighbor 10.3.4.4
  address-family ipv4 unicast
   route-policy EBGP-OUT-LOCAL out
  !
 !
!
end

The transit route is back to ?. In the same No.3 UPDATE, only 192.168.66.0/24 carries INCOMPLETE (2).

STEP 4 R3 - R4 No.3 UPDATE (R3 to R4, 192.168.66.0/24) tshark -V (excerpt)
Border Gateway Protocol - UPDATE Message
<snip>
        Path Attribute - MP_REACH_NLRI
<snip>
            Next hop: 10.3.4.3
<snip>
                192.168.66.0/24
<snip>
        Path Attribute - ORIGIN: INCOMPLETE
<snip>
            Origin: INCOMPLETE (2)
        Path Attribute - AS_PATH: 65001 65004 
<snip>
                AS4: 65001
                AS4: 65004

Download the pcap of the packet in the tshark output above (STEP 4 No.3, transit route at 2)

R4’s table shows the split as well: 192.168.99.0/24 is i while 192.168.66.0/24 is ?.

R4 show bgp (STEP 4)
RP/0/RP0/CPU0:R4#show bgp
Sun Sep 27 13:00:53.285 UTC
BGP router identifier 10.0.0.4, local AS number 65002
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0xe0000000   RD version: 13
BGP main routing table version 13
BGP NSR Initial initsync version 4 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*> 192.168.1.0/24     10.3.4.3                               0 65001 i
*> 192.168.2.0/24     10.3.4.3                               0 65001 i
*> 192.168.3.0/24     10.3.4.3                 0             0 65001 i
*> 192.168.4.0/24     0.0.0.0                  0         32768 i
*> 192.168.5.0/24     10.4.5.5                 0             0 65003 i
*> 192.168.6.0/24     10.3.4.3                               0 65001 65004 i
*> 192.168.66.0/24    10.3.4.3                               0 65001 65004 ?
*> 192.168.99.0/24    10.3.4.3                 0             0 65001 i

Processed 8 prefixes, 8 paths

advertised-routes displays 65001 in the AS path, but that is prepended after the policy runs. The policy sees an empty AS_PATH, which matches ^$, while 192.168.66.0/24 already carried 65004 and does not match.

192.168.1.0/24 and 192.168.2.0/24 match ^$ too, but they were already IGP, so nothing visibly changes.

Verification Configs and show Output

Each STEP captures the following files from all six routers, one file per router and kind. The verification config is the ..._run.txt (final state: STEP 4).

File	Contents
`..._show.txt`	`show version` / `show interface description` / `show route` / `show bgp` / `show bgp summary` / `show route bgp` / `show bgp` for `192.168.99.0/24`, `192.168.6.0/24` and `192.168.66.0/24` / `show bgp neighbors` / per-peer `advertised-routes`, `routes` and `received routes` / `show bgp update-group` / `show bgp process` / `show rpl route-policy`. R1 to R3 also include `show ospf neighbor` / `show route ospf`; R1 and R3 include `show route 192.168.99.0/24` (R3 also `show cef`)
`..._log.txt`	`show logging` limited to that STEP
`..._run.txt`	`show running-config` at that STEP (the verification config for that STEP)
`..._ping.txt`	50 pings and a traceroute from R4 and R5 to `192.168.99.1`
`..._trace.txt`	`show bgp trace neighbor` and `show bgp trace error`
`..._commit.cfg`	The configuration actually committed in that STEP (only the routers that were changed)

STEP 0: initial state (an i route and a ? route)

Router	show output	syslog	running-config	ping	trace	Committed config
R1	show	log	run	—	trace	—
R2	show	log	run	—	trace	—
R3	show	log	run	—	trace	—
R4	show	log	run	ping	trace	—
R5	show	log	run	ping	trace	—
R6	show	log	run	—	trace	—

STEP 1: remove network 192.168.99.0/24 from R1

Router	show output	syslog	running-config	ping	trace	Committed config
R1	show	log	run	—	trace	commit
R2	show	log	run	—	trace	—
R3	show	log	run	—	trace	—
R4	show	log	run	ping	trace	—
R5	show	log	run	ping	trace	—
R6	show	log	run	—	trace	—

STEP 2: restore network on R1

Router	show output	syslog	running-config	ping	trace	Committed config
R1	show	log	run	—	trace	commit
R2	show	log	run	—	trace	—
R3	show	log	run	—	trace	—
R4	show	log	run	ping	trace	—
R5	show	log	run	ping	trace	—
R6	show	log	run	—	trace	—

STEP 3: apply EBGP-OUT-ALL on R3 (level every route to IGP)

Router	show output	syslog	running-config	ping	trace	Committed config
R1	show	log	run	—	trace	—
R2	show	log	run	—	trace	—
R3	show	log	run	—	trace	commit
R4	show	log	run	ping	trace	—
R5	show	log	run	ping	trace	—
R6	show	log	run	—	trace	—

STEP 4: apply EBGP-OUT-LOCAL on R3 (^$ only, final state)

Router	show output	syslog	running-config	ping	trace	Committed config
R1	show	log	run	—	trace	—
R2	show	log	run	—	trace	—
R3	show	log	run	—	trace	commit
R4	show	log	run	ping	trace	—
R5	show	log	run	ping	trace	—
R6	show	log	run	—	trace	—

Packet captures were taken per STEP.

STEP	R3 - R4	R4 - R5	R1 - R6
0	pcap	pcap	pcap
1	pcap	pcap	pcap
2	pcap	pcap	pcap
3	pcap	pcap	pcap
4	pcap	pcap	pcap

References

Source	Title	Summary
RFC 4271	A Border Gateway Protocol 4 (BGP-4)	Section 4.3 defines the three `ORIGIN` values, 5.1.1 how it is generated and that it should not be changed, 9.1.2.2 the comparison in best path selection and 9.2.2.2 the value for aggregates.
RFC 904	Exterior Gateway Protocol Formal Specification	The protocol the `EGP` value refers to; no longer used.
IANA	Border Gateway Protocol (BGP) Parameters	Registry of numbers used in BGP, including path attribute type codes.