JunOS BGP/LAG/OSPF

In this Tutorial We will be discussing how to setup an External Border Gateway Protocol (EBGP) between two routers.

Prerequisites

To complete this tutorial, you will need:

• A laptop running Linux or MacOS. for this tutorial I will be using a laptop running Ubuntu 16
• A console cable. Since all the new laptops today don't come with a console port, you will need a USB to Console adapter
• The program "Screen"

If you don't have "screen" install it with the command below

sudo apt-get install screen

Goal 1: BGP

Goal 1 is to setup the network like in the above image.

We have 2 offices. One in Texas and the other one in San Fransisco. Both offices have a Juniper MX80 router. The Texas router cr1-tx is in AS 17 and the San Fransico router cr1-sfo is in AS 29. We need to setup an External Border Gateway Protocol (EBGP) to connect both offices. If we were to connect 2 router in the same AS, we was going to use an IBGP (Internal Border Gateway Protocol) such as OSPF. We will discuss about this in another tutorial.

Router Setup

We are going to perform the basic setup of the router like we did for the switches in [[JunOS Basics[1]]

The process is the same. Please refer to the link above

• Access the router
• Setup the root password
• Setup the device name
• Create a privilege user
• setup Management interface and enable SSH

Note: for the management setup, since we are using a router the management interface on the MX80 is not me0 like on the switch. The management interface is fxp0. See below for the how the management interface is setup.

root@cr1-tx# show interfaces 
fxp0 {
    description mgmt;
    unit 0 {
        family inet {
            address 10.192.0.103/24;
        }
    }
}

After setting up all the basic on both routers, it is time to process to the EBGP setup.

EBGP Setup

On cr1-tx

We are going to use the interface xe-0/0/0 which is a 10Gbs interfaces.

Step 1: Set interface description

set interfaces xe-0/0/0 description to-cr1-sfo

• Check before committing

root@cr1-tx# show | compare                                        
[edit interfaces]
+   xe-0/0/0 {
+       description to-cr1-sfo;
+   }

Step 2: Assign an IP address to the interface

set interfaces xe-0/0/0 unit 0 family inet address 10.10.10.1/30

• Check before committing

root@cr1-tx# show | compare 
[edit interfaces xe-0/0/0]
+    unit 0 {
+        family inet {
+            address 10.10.10.1/30;
+        }
+    }

Step 3: Set the Autonomous system (AS) number To set the AS number we need to be in the routing-options level for that type in

edit routing-options 

[edit routing-options]
root@cr1-tx# set autonomous-system 17 

step 4 : Create the BGP group/ add external neighbor address

To do this we need to be in the protocols bgp group external-peers level

Type "exit" to leave the routing-options level and then type in

[edit]
root@cr1-tx# edit protocols bgp group external-peers

[edit protocols bgp group external-peers]
root@cr1-tx# set neighbor 10.10.10.2   

Step 5: Specify external AS number

[edit protocols bgp group external-peers]
root@cr1-tx# set peer-as 29 

Step 6: Set the peer type

[edit protocols bgp group external-peers]
root@cr1-tx# set type external 

Type " exit"

Checking

[edit]
root@cr1-tx# show interfaces 
xe-0/0/0 {
    description to-cr1-sfo;
    unit 0 {
        family inet {
            address 10.10.10.1/30;
        }
    }
}

[edit]
root@cr1-tx# show protocols 
bgp {
    group external-peers {
        type external;
        peer-as 29;
        neighbor 10.10.10.2;
    }
}

[edit]
root@cr1-tx# show routing-options 
autonomous-system 17;

If everything looks good, you can commit

Verification

In operation mode,do show run neighbor

root@cr1-tx> show bgp neighbor 
Peer: 10.10.10.2 AS 29         Local: unspecified AS 17   
  Type: External    State: Idle           Flags: <PeerInterfaceError>
  Last State: NoState       Last Event: NoEvent
  Last Error: None
  Options: <Preference PeerAS Refresh>
  Holdtime: 90 Preference: 170
  Number of flaps: 0

We can see from the output the Local= unspecified and the state is Idle Last State: NoState Last Event: NoEvent. The reason being that we haven't setup cr1-sfo yet.

On cr1-sfo

We are going to use the interface xe-0/0/0 which is a 10Gbs interfaces.

Step 1: Set interface description

[edit]
root@cr1-sfo# set interfaces xe-0/0/0 description to-cr1-sfo

Step 2: Assign an IP address to the interface

set interfaces xe-0/0/0 unit 0 family inet address 10.10.10.2/30

• Check before committing

root@cr1-sfo# show | compare 
[edit interfaces]
+   xe-0/0/0 {
+       description to-cr1-sfo;
+       unit 0 {
+           family inet {
+               address 10.10.10.2/30;
+           }
+       }
+   }

Step 3: Set the Autonomous system (AS) number

To set the AS number we need to be in the routing-options level for that type in

edit routing-options

[edit routing-options]
root@cr1-tx# set autonomous-system 29 

step 4 : Create the BGP group/ add external neighbor address

To do this we need to be in the protocols bgp group external-peers level

Type "exit" to leave the routing-options level and then type in

[edit]
root@cr1-tx# edit protocols bgp group external-peers

[edit protocols bgp group external-peers]
root@cr1-tx# set neighbor 10.10.10.1   

Step 5: Specify external AS number

[edit protocols bgp group external-peers]
root@cr1-tx# set peer-as 17 

Step 6: Set the peer type

[edit protocols bgp group external-peers]
root@cr1-tx# set type external 

Type " exit"

Checking

[edit]
root@cr1-sfo# show interfaces 
xe-0/0/0 {
    description cr1-sfo;
    unit 0 {
        family inet {
            address 10.10.10.2/30;
        }
    }
}

[edit]
root@cr1-sfo# show protocols 
bgp {
    group external-peers {
        type external;
        peer-as 17;
        neighbor 10.10.10.1;
    }
} 

[edit]
root@cr1-sfo# show routing-options 
autonomous-system 29;

Now that we have cr1-sfo setup let us go back to cr1-tx and run again "show bgp neighbor"

Verification

• On cr1-tx

root@cr1-tx> show bgp neighbor 
Peer: 10.10.10.2+55085 AS 29   Local: 10.10.10.1+179 AS 17   
 Type: External    State: Established    Flags: <Sync>
 Last State: OpenConfirm   Last Event: RecvKeepAlive
 Last Error: None
 Options: <Preference PeerAS Refresh>
 Holdtime: 90 Preference: 170
 Number of flaps: 0
 Peer ID: 10.10.10.2      Local ID: 10.10.10.1        Active Holdtime: 90
 Keepalive Interval: 30         Group index: 0    Peer index: 0   
 BFD: disabled, down
 Local Interface: xe-0/0/0.0                       
 NLRI for restart configured on peer: inet-unicast
 NLRI advertised by peer: inet-unicast
 NLRI for this session: inet-unicast
 Peer supports Refresh capability (2)
 Stale routes from peer are kept for: 300
 Peer does not support Restarter functionality
 NLRI that restart is negotiated for: inet-unicast
 NLRI of received end-of-rib markers: inet-unicast
 NLRI of all end-of-rib markers sent: inet-unicast
 Peer supports 4 byte AS extension (peer-as 29)
 Peer does not support Addpath
 Table inet.0 Bit: 10000
   RIB State: BGP restart is complete
   Send state: in sync
   Active prefixes:              0
   Received prefixes:            0
   Accepted prefixes:            0
   Suppressed due to damping:    0
   Advertised prefixes:          0
 Last traffic (seconds): Received 10   Sent 6    Checked 65  
 Input messages:  Total 5      Updates 1       Refreshes 0     Octets 139
 Output messages: Total 5      Updates 0       Refreshes 0     Octets 158
 Output Queue[0]: 0

• On cr1-sfo

root@cr1-sfo> show bgp neighbor 
Peer: 10.10.10.1+179 AS 17     Local: 10.10.10.2+55085 AS 29   
 Type: External    State: Established    Flags: <Sync>
 Last State: OpenConfirm   Last Event: RecvKeepAlive
 Last Error: None
 Options: <Preference PeerAS Refresh>
 Holdtime: 90 Preference: 170
 Number of flaps: 0
 Peer ID: 10.10.10.1      Local ID: 10.10.10.2        Active Holdtime: 90
 Keepalive Interval: 30         Group index: 0    Peer index: 0   
 BFD: disabled, down
 Local Interface: xe-0/0/0.0                       
 NLRI for restart configured on peer: inet-unicast
 NLRI advertised by peer: inet-unicast
 NLRI for this session: inet-unicast
 Peer supports Refresh capability (2)
 Stale routes from peer are kept for: 300
 Peer does not support Restarter functionality
 NLRI that restart is negotiated for: inet-unicast
 NLRI of received end-of-rib markers: inet-unicast
 NLRI of all end-of-rib markers sent: inet-unicast
 Peer supports 4 byte AS extension (peer-as 17)
 Peer does not support Addpath
 Table inet.0 Bit: 10000
   RIB State: BGP restart is complete
   Send state: in sync
   Active prefixes:              0
   Received prefixes:            0
   Accepted prefixes:            0
   Suppressed due to damping:    0
   Advertised prefixes:          0
 Last traffic (seconds): Received 2    Sent 18   Checked 23  
 Input messages:  Total 15     Updates 1       Refreshes 0     Octets 289
 Output messages: Total 16     Updates 0       Refreshes 0     Octets 367
 Output Queue[0]: 0

We have setup peering between cr1-tx and cr1-sfo.

BGP verification commands

show bgp neighbor

show bgp group 

show bgp summary

Goal 2: LAC

Link aggregation enables you to group interfaces to form a single link layer interface; also knows as a LAG (Link Aggregation Group).

In goal 2, we are going to setup Link Aggregation group (LAG) with Link Aggregation Control Protocol (LACP) between cr1 and cr2 using interfaces xe-1/0/0 and xe-1/2/0 on both routers.

This needs to be done on both routers

On cr1

• Step 1: Create the aggregation Ethernet Interface(s)

In "Edit" or "configuration mode", run:

set chassis aggregated-devices ethernet device-count 1

This will create 1 aggregated ethernet interface (ae0) because of the number 1 after device-count. If device-count was = 3, this will create 3 ae's (ae0, ae1 and ae3). commit the changes

[edit]
root@cr1-tx# run show interfaces terse | match ae                      
ae0                     up    down

• Step 2: Specify the number of interfaces

edit]
root@cr1-tx# set interfaces xe-1/0/0  gigether-options 802.3ad ae0 
root@cr1-tx# set interfaces xe-1/2/0  gigether-options 802.3ad ae0 

Note: If you was using a 1G interface, replace gigether-options with ether-options

• Step 3: Specify an interface family and interface properties

root@cr1-tx# set interfaces ae0 unit 0 family inet address 10.192.0.105/24 
root@cr1-tx# set interfaces ae0 aggregated-ether-options lacp active

commit and verify.

[edit]
root@cr1-tx# run show interfaces terse | match ae   
xe-1/0/0.0              up    up   aenet    --> ae0.0
xe-1/2/0.0              up    up   aenet    --> ae0.0
ae0                     up    down
ae0.0                   up    down inet     192.168.0.1/30

We see both ae0 and ae0.0 are showing down. This is because we haven't configured cr2 yet.

On cr2

Perform the same steps on cr2 and change the IP address to 10.192.0.106. Below is the configuration of cr2 before commit

root@cr2-tx# show | compare 
[edit interfaces]
+   xe-1/0/0 {
+       gigether-options {
+           802.3ad ae0;
+       }
+   }
+   xe-1/2/0 {
+       gigether-options {
+           802.3ad ae0;
+       }
+   }
+   ae0 {
+       aggregated-ether-options {
+           lacp {
+               active;
+           }
+       }
+       unit 0 {
+           family inet {
+               address 192.168.0.2/30;
+           }
+       }
+   }

Verification

[edit]
root@cr1-tx# run show interfaces terse | match ae    
xe-1/0/0.0              up    up   aenet    --> ae0.0
xe-1/2/0.0              up    up   aenet    --> ae0.0
ae0                     up    up
ae0.0                   up    up   inet     192.168.0.1/30

[edit]
root@cr2-tx# run show interfaces terse | match ae 
xe-1/0/0.0              up    up   aenet    --> ae0.0
xe-1/2/0.0              up    up   aenet    --> ae0.0
ae0                     up    up
ae0.0                   up    up   inet     192.168.0.2/30

Testing

From cr1-tx ping 192.168.0.2

root@cr1-tx> ping 192.168.0.2 
PING 192.168.0.2 (192.168.0.2): 56 data bytes
64 bytes from 192.168.0.2: icmp_seq=0 ttl=64 time=0.832 ms
64 bytes from 192.168.0.2: icmp_seq=1 ttl=64 time=0.759 ms
64 bytes from 192.168.0.2: icmp_seq=2 ttl=64 time=0.758 ms

From cr2-tx ping 192.168.0.1

root@cr2-tx> ping 192.168.0.1 
PING 192.168.0.1 (192.168.0.1): 56 data bytes
64 bytes from 192.168.0.1: icmp_seq=0 ttl=64 time=0.779 ms
64 bytes from 192.168.0.1: icmp_seq=1 ttl=64 time=0.704 ms
64 bytes from 192.168.0.1: icmp_seq=2 ttl=64 time=16.159 ms

Goal 3

In goal 2 we used 2 interfaces on each router to set a LAC (ae0). In Goal 3 we are going to setup OSPF on the ae0 interface.