Origin

Three types of Origin attributes are available:

IGP: indicates that routes are added to the BGP routing table using the network command. IGP has the highest priority.
EGP: indicates that routes are learned through the EGP protocol. EGP has the second highest priority.

The switch can receive and send BGP routes with EGP as the Origin. However, the switch does not support the EGP protocol; therefore, to set the Origin of routes to EGP, you need to run the apply origin { egp { as-number-plain | as-number-dot } | igp | incomplete } command to configure an apply clause for a route-policy.
Incomplete: indicates that routes are added to the BGP routing table using the import-route command. Incomplete has the lowest priority.

The routes imported using the network command are more specific than those imported using the import-route command. Therefore, IGP takes precedence over Incomplete in route selection. In Figure 1, Switch A and Switch B are EBGP peers, and Switch B, Switch C, and Switch D are IBGP peers.

Figure 1 Networking diagram with Origin configurations

The configurations on Switch D are as follows:

#
bgp 65001
 #
 ipv4-family unicast
  network 10.1.4.0 255.255.255.252                       //Advertise the route 10.1.4.0/30.
#

The configurations on Switch C are as follows:

#
bgp 65001
 #
 ipv4-family unicast
  import-route direct                                   //Import direct routes.
#

Run the display bgp routing-table [ ip-address ] command to check the configurations.

# Display the routing table of Switch B.

[HUAWEIB] display bgp routing-table

 BGP Local router ID is 10.1.1.2
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete


 Total Number of Routes: 3
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

   i  10.1.2.0/30        10.1.2.2        0          100        0      ?
 *>i  10.1.4.0/30        10.1.3.2        0          100        0      i
 * i                     10.1.2.2        0          100        0      ?

The preceding command output shows that two active routes 10.1.4.0/30 are available in the routing table.

[HUAWEIB] display bgp routing-table 10.1.4.0

 
 BGP local router ID : 10.1.1.2
 Local AS number : 65001
 Paths:   2 available, 1 best, 1 select
 BGP routing table entry information of 10.1.4.0/30:
 From: 10.1.3.2 (10.1.3.2)
 Route Duration: 01h14m48s
 Relay IP Nexthop: 0.0.0.0
 Relay IP Out-Interface: GigabitEthernet0/0/2
 Original nexthop: 10.1.3.2
 Qos information : 0x0
 AS-path Nil, origin igp, MED 0, localpref 100, pref-val 0, valid, internal, best, select, active, pre 255
 Advertised to such 1 peers:
    10.1.1.1

 BGP routing table entry information of 10.1.4.0/30:
 From: 10.1.2.2 (10.1.2.2)
 Route Duration: 01h13m20s
 Relay IP Nexthop: 0.0.0.0
 Relay IP Out-Interface: GigabitEthernet0/0/0
 Original nexthop: 10.1.2.2
 Qos information : 0x0
 AS-path Nil, origin incomplete, MED 0, localpref 100, pref-val 0, valid, internal, pre 255, not preferred for Origin
 Not advertised to any peer yet

The preceding command output shows that the route learned from Switch D is selected because it is imported using the network command and its Origin priority is higher than that of the route learned from Switch C. Table 1 describes the attribute comparison of the routes learned from Switch C and Switch D.

**Table 1** Attribute comparison of the routes learned from Switch C and Switch D
Route Attribute	Route Learned from Switch C	Route Learned from Switch D	Comparison
PrefVal	0	0	The same.
Local_Pref	100	100	The same.
Route type	Learned from a peer	Learned from a peer	The same.
AIGP	-	-	The same.
AS_Path	-	-	The same length.
Origin	Incomplete	IGP	The route learned from Switch D is optimal.

The Origin attribute can be modified using a route-policy. In the following example, a route-policy is configured on Switch B to modify the Origin attribute, and the detailed configurations are as follows:

#
bgp 65001
 #
 ipv4-family unicast
  peer 10.1.3.2 route-policy for_d import              //Apply import policy named for_d to the routes learned from 10.1.3.2 and use for_d to modify the Origin value.
#
route-policy for_d permit node 10                      //Define the route-policy named for_d.
 apply origin incomplete                               //Set the Origin type to Incomplete.

Run the display bgp routing-table [ ip-address ] command to check the configurations.

# Display the routing table of Switch B.

[HUAWEIB] display bgp routing-table

 BGP Local router ID is 10.1.1.2
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete


 Total Number of Routes: 3
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

   i  10.1.2.0/30        10.1.2.2        0          100        0      ?
 *>i  10.1.4.0/30        10.1.2.2        0          100        0      ?
 * i                     10.1.3.2        0          100        0      ?

The preceding command output shows that the route learned from Switch C becomes the optimal route.

[HUAWEIB] display bgp routing-table 10.1.4.0

 BGP local router ID : 10.1.1.2
 Local AS number : 65001
 Paths:   2 available, 1 best, 1 select
 BGP routing table entry information of 10.1.4.0/30:
 From: 10.1.2.2 (10.1.2.2)
 Route Duration: 01h28m19s
 Relay IP Nexthop: 0.0.0.0
 Relay IP Out-Interface: GigabitEthernet0/0/0
 Original nexthop: 10.1.2.2
 Qos information : 0x0
 AS-path Nil, origin incomplete, MED 0, localpref 100, pref-val 0, valid, internal, best, select, active, pre 255
 Advertised to such 1 peers:
    10.1.1.1

 BGP routing table entry information of 10.1.4.0/30:
 From: 10.1.3.2 (10.1.3.2)
 Route Duration: 00h03m18s
 Relay IP Nexthop: 0.0.0.0
 Relay IP Out-Interface: GigabitEthernet0/0/2
 Original nexthop: 10.1.3.2
 Qos information : 0x0
 AS-path Nil, origin incomplete, MED 0, localpref 100, pref-val 0, valid, internal, pre 255, not preferred for router ID
 Not advertised to any peer yet

The preceding command output shows that the route learned from Switch C becomes the optimal route because it has a smaller router ID than the route learned from Switch D. Table 2 shows the attribute comparison of the routes learned from Switch C and Switch D.

**Table 2** Attribute comparison of the routes learned from Switch C and Switch D
Route Attribute	Route Learned from Switch C	Route Learned from Switch D	Comparison
PrefVal	0	0	The same.
Local_Pref	100	100	The same.
Route type	Learned from a peer	Learned from a peer	The same.
AIGP	-	-	The same.
AS_Path	-	-	The same.
Origin	Incomplete	Incomplete	The same.
MED	0	0	The same.
Peer type	IBGP	IBGP	The same.
IGP cost	-	-	The same.
Cluster_List	-	-	The same.
Router ID	10.1.2.2	10.1.3.2	The route learned from Switch C is optimal.