AR100, AR120, AR150, AR160, AR200, AR1200, AR2200, AR3200, and AR3600 V200R010 CLI-based Configuration Guide - IP Unicast Routing

This document describes the concepts and configuration procedures of IP Service features on the device, and provides the configuration examples.

Example for Configuring AS_Path Filters

Networking Requirements

On the network shown in Figure 9-30, Router B establishes EBGP connections with Routers A and C. The user wants to disable the devices in AS 10 from communicating with devices in AS 30.

Figure 9-30 Networking diagram for configuring AS_Path filters

Configuration Roadmap

The configuration roadmap is as follows:

Establish EBGP connections between Routers A and B and between Routers B and C and configure these devices to import direct routes so that the ASs can communicate with each other through these EBGP connections.
Configure AS_Path filters on Router B and use filtering rules to prevent AS 20 from advertising routes of AS 30 to AS 10 or routes of AS 10 to AS 30.

Procedure

Configure an IP address for each interface.

# Configure IP addresses for all interfaces of Router A.

<Huawei> system-view
[Huawei] sysname RouterA
[RouterA] interface gigabitethernet 1/0/0
[RouterA-GigabitEthernet1/0/0] ip address 9.1.1.1 255.255.255.0
[RouterA-GigabitEthernet1/0/0] quit
[RouterA] interface gigabitethernet 2/0/0
[RouterA-GigabitEthernet2/0/0] ip address 200.1.2.1 255.255.255.0
[RouterA-GigabitEthernet2/0/0] quit

The configurations of RouterB and RouterC are similar to the configuration of RouterA, and are not mentioned here.

Establish EBGP connections.

# Configure Router A.

[RouterA] bgp 10

[RouterA-bgp] router-id 1.1.1.1

[RouterA-bgp] peer 200.1.2.2 as-number 20

[RouterA-bgp] import-route direct

# Configure Router B.

[RouterB] bgp 20

[RouterB-bgp] router-id 2.2.2.2

[RouterB-bgp] peer 200.1.2.1 as-number 10

[RouterB-bgp] peer 200.1.3.2 as-number 30

[RouterB-bgp] import-route direct

[RouterB-bgp] quit

# Configure Router C.

[RouterC] bgp 30

[RouterC-bgp] router-id 3.3.3.3

[RouterC-bgp] peer 200.1.3.1 as-number 20

[RouterC-bgp] import-route direct

[RouterC-bgp] quit

# View routes advertised by Router B. Routes advertised by Router B to Router C are used as an example. You can see that Router B advertises the direct route imported by AS 10.

<RouterB> display bgp routing-table peer 200.1.3.2 advertised-routes

 BGP Local router ID is 2.2.2.2
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete


 Total Number of Routes: 5
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>   9.1.1.0/24        200.1.3.1                           0      20 10?
 *>   10.1.1.0/24        200.1.3.1                             0      20 30?
 *>   200.1.2.0          200.1.3.1       0                     0      20?
 *>   200.1.2.1/32       200.1.3.1       0                     0      20?
 *>   200.1.3.0/24       200.1.3.1       0                     0      20?

View the routing table of Router C. You can see that Router C has learned the direct route from Router B.

<RouterC> display bgp routing-table

 BGP Local router ID is 3.3.3.3
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete

 Total Number of Routes: 9
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>   9.1.1.0/24        200.1.3.1                            0      20 10?
 *>   10.1.1.0/24        0.0.0.0         0                     0      ?
 *>   10.1.1.1/32        0.0.0.0         0                     0      ?
 *>   127.0.0.0          0.0.0.0         0                     0      ?
 *>   127.0.0.1/32       0.0.0.0         0                     0      ?
 *>   200.1.2.0          200.1.3.1       0                     0      20?
 *>   200.1.3.0/24       0.0.0.0         0                     0      ?
 *                       200.1.3.1       0                     0      20?
 *>   200.1.3.2/32       0.0.0.0         0                     0      ?

Configure AS_Path filters on Router B and apply the AS_Path filters to routes to be advertised by Router B.
# Create AS_Path filter 1 to deny the routes carrying AS number 30. The regular expression "_30_" indicates any AS list that contains AS 30 and "*" matches any character.
```
[RouterB] ip as-path-filter path-filter1 deny _30_
```
```
[RouterB] ip as-path-filter path-filter1 permit .*
```
# Create AS_Path filter 2 to deny the routes carrying AS 10.
```
[RouterB] ip as-path-filter path-filter2 deny _10_
```
```
[RouterB] ip as-path-filter path-filter2 permit .*
```
# Apply the AS_Path filters to routes to be advertised by Router B.
```
[RouterB] bgp 20
```
```
[RouterB-bgp] peer 200.1.2.1 as-path-filter path-filter1 export
```
```
[RouterB-bgp] peer 200.1.3.2 as-path-filter path-filter2 export
```
```
[RouterB-bgp] quit
```

# View routes advertised by Router B.

# View routes advertised by Router B to AS 30. You can see that Router B does not advertise the direct route imported by AS 10.

<RouterB> display bgp routing-table peer 200.1.3.2 advertised-routes

 BGP Local router ID is 2.2.2.2
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete


 Total Number of Routes: 2
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>   200.1.2.0          200.1.3.1       0                     0      20?
 *>   200.1.3.0/24       200.1.3.1       0                     0      20?

The route does not exist in the BGP routing table of Router C.

<RouterC> display bgp routing-table

 BGP Local router ID is 3.3.3.3
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete

 Total Number of Routes: 8
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>   10.1.1.0/24        0.0.0.0         0                     0      ?
 *>   10.1.1.1/32        0.0.0.0         0                     0      ?
 *>   127.0.0.0          0.0.0.0         0                     0      ?
 *>   127.0.0.1/32       0.0.0.0         0                     0      ?
 *>   200.1.2.0          200.1.3.1       0                     0      20?
 *>   200.1.3.0/24       0.0.0.0         0                     0      ?
 *                       200.1.3.1       0                     0      20?
 *>   200.1.3.2/32       0.0.0.0         0                     0      ?

# View routes advertised by Router B to AS 10. You can see that Router B does not advertise the direct route imported by AS 30.

<RouterB> display bgp routing-table peer 200.1.2.1 advertised-routes

 BGP Local router ID is 2.2.2.2
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete


 Total Number of Routes: 2
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>   200.1.2.0          200.1.2.2       0                     0      20?
 *>   200.1.3.0/24       200.1.2.2       0                     0      20?

The route does not exist in the BGP routing table of Router A.

<RouterA> display bgp routing-table

 BGP Local router ID is 1.1.1.1
 Status codes: * - valid, > - best, d - damped,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete

 Total Number of Routes: 8
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>   9.1.1.0/24         0.0.0.0         0                     0      ?
 *>   9.1.1.1/32         0.0.0.0         0                     0      ?
 *>   127.0.0.0          0.0.0.0         0                     0      ?
 *>   127.0.0.1/32       0.0.0.0         0                     0      ?
 *>   200.1.2.0          0.0.0.0         0                     0      ?
 *                       200.1.2.2       0                     0      20?
 *>   200.1.2.1/32       0.0.0.0         0                     0      ?
 *>   200.1.3.0/24       200.1.2.2       0                     0      20?

Configuration Files

Configuration file of Router A

 sysname RouterA

interface GigabitEthernet1/0/0

 ip address 9.1.1.1 255.255.255.0

interface GigabitEthernet2/0/0

 ip address 200.1.2.1 255.255.255.0

bgp 10

 router-id 1.1.1.1

 peer 200.1.2.2 as-number 20

 ipv4-family unicast

  undo synchronization

  import-route direct

  peer 200.1.2.2 enable

return

Configuration file of Router B

 sysname RouterB

interface GigabitEthernet1/0/0

 ip address 200.1.3.1 255.255.255.0

interface GigabitEthernet2/0/0

 ip address 200.1.2.2 255.255.255.0

bgp 20

 router-id 2.2.2.2

 peer 200.1.2.1 as-number 10

 peer 200.1.3.2 as-number 30

 ipv4-family unicast

  undo synchronization

  import-route direct

  peer 200.1.2.1 enable

  peer 200.1.2.1 as-path-filter path-filter1 export

  peer 200.1.3.2 enable

  peer 200.1.3.2 as-path-filter path-filter2 export

 ip as-path-filter path-filter1 deny _30_

 ip as-path-filter path-filter1 permit .*

 ip as-path-filter path-filter2 deny _10_

 ip as-path-filter path-filter2 permit .*

return

Configuration file of Router C

 sysname RouterC

interface GigabitEthernet1/0/0

 ip address 10.1.1.1 255.255.255.0

interface GigabitEthernet2/0/0

 ip address 200.1.3.2 255.255.255.0

bgp 30

 router-id 3.3.3.3

 peer 200.1.3.1 as-number 20

 ipv4-family unicast

  undo synchronization

  import-route direct

  peer 200.1.3.1 enable

return

Translation

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Update Date：2023-08-07

Document ID：EDOC1100034072

Downloads：1387

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