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[MX] Example - How to bring up the routing protocol via GRE over GRE on MX routers

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Article ID: KB36271 KB Last Updated: 27 Oct 2020Version: 1.0 Summary:

This article demonstrates how to bring up a routing protocol via GRE over GRE on MX routers with the help of an example for users who might want to do so.

 

Solution:

Lab Configuration

  • user@MX80-A is MX80 with logical system R1 and R3.

  • user@MX80-B is MX80 with logical system R2 and R4.

  • Both routers are running Junos OS Release 19.2R1.8.

Topology 

R3(xe0/0/3) ------ (xe0/0/0)R1(xe0/0/2) ------ (xe0/0/2)R2(xe0/0/0) ------ (xe0/0/1)R4

Lo0 3.3.3.3/32             Lo0 1.1.1.1/32                          Lo0 2.2.2.2/32                Lo0 4.4.4.4/32

Steps

  1. Create the GRE port gr-0/0/0 on R1 and R2, the target logical topology, as shown below:

R3(xe0/0/3)-----(xe0/0/0)R1(gr-0/0/0)---------------(gr-0/0/0)R2(xe0/0/0)-----(xe0/0/1)R4

  • GRE interface on R1

labroot@MX80-A> show interfaces gr-0/0/0    
Physical interface: gr-0/0/0, Enabled, Physical link is Up
  Interface index: 174, SNMP ifIndex: 555
  Type: GRE, Link-level type: GRE, MTU: Unlimited, Speed: 100000mbps
  Device flags   : Present Running
  Interface flags: Point-To-Point SNMP-Traps
  Input rate     : 688 bps (1 pps)
  Output rate    : 360 bps (0 pps)

  Logical interface gr-0/0/0.0 (Index 342) (SNMP ifIndex 1062)
    Flags: Up Point-To-Point SNMP-Traps 0x0 IP-Header 2.2.2.2:1.1.1.1:47:df:64:00000000000a000a Encapsulation: GRE-NULL
    Copy-tos-to-outer-ip-header: Off, Copy-tos-to-outer-ip-header-transit: Off
    Gre keepalives configured: Off, Gre keepalives adjacency state: down
    Input packets : 59
    Output packets: 60
    Protocol inet, MTU: 1476
    Max nh cache: 0, New hold nh limit: 0, Curr nh cnt: 0, Curr new hold cnt: 0, NH drop cnt: 0
      Flags: Sendbcast-pkt-to-re
      Addresses, Flags: Is-Preferred Is-Primary
        Destination: 172.16.1/24, Local: 172.16.1.1, Broadcast: 172.16.1.255
  • GRE interface on R2
user@MX80-B> show interfaces gr-0/0/0 
Physical interface: gr-0/0/0, Enabled, Physical link is Up
  Interface index: 174, SNMP ifIndex: 620
  Type: GRE, Link-level type: GRE, MTU: Unlimited, Speed: 100000mbps
  Device flags   : Present Running
  Interface flags: Point-To-Point SNMP-Traps
  Input rate     : 688 bps (0 pps)
  Output rate    : 360 bps (0 pps)

  Logical interface gr-0/0/0.0 (Index 341) (SNMP ifIndex 938)
    Flags: Up Point-To-Point SNMP-Traps 0x0 IP-Header 1.1.1.1:2.2.2.2:47:df:64:0000000000090009 Encapsulation: GRE-NULL
    Copy-tos-to-outer-ip-header: Off, Copy-tos-to-outer-ip-header-transit: Off
    Gre keepalives configured: Off, Gre keepalives adjacency state: down
    Input packets : 67
    Output packets: 69
    Protocol inet, MTU: 1476
    Max nh cache: 0, New hold nh limit: 0, Curr nh cnt: 0, Curr new hold cnt: 0, NH drop cnt: 0
      Flags: Sendbcast-pkt-to-re
      Addresses, Flags: Is-Preferred Is-Primary
        Destination: 172.16.1/24, Local: 172.16.1.2, Broadcast: 172.16.1.255
  • Ping test between R1 and R2 via GRE interface gr-0/0/0
user@MX80-A> ping 172.16.1.2 source 172.16.1.1 logical-system R1 count 2 
PING 172.16.1.2 (172.16.1.2): 56 data bytes
64 bytes from 172.16.1.2: icmp_seq=0 ttl=64 time=1.533 ms
64 bytes from 172.16.1.2: icmp_seq=1 ttl=64 time=0.959 ms

  1. Apply the routing protocol OSPF to ensure reachability between R3 and R4 via the GRE port and OSPF.

  • OSPF neighbor between R1 and R2 via GRE port

user@MX80-A> show ospf neighbor logical-system R1 
Address          Interface              State     ID               Pri  Dead
172.16.1.2       gr-0/0/0.0             Full      2.2.2.2          128    31
13.1.1.3         xe-0/0/0.0             Full      3.3.3.3          128    31

user@MX80-B> show ospf neighbor logical-system R2 
Address          Interface              State     ID               Pri  Dead
172.16.1.1       gr-0/0/0.0             Full      1.1.1.1          128    35
24.1.1.4         xe-0/0/0.0             Full      4.4.4.4          128    39

  • Ping test between R3 and R4 through the physical port and OSPF

user@MX80-A> ping 24.1.1.4 source 13.1.1.3 logical-system R3 count 2 

PING 24.1.1.4 (24.1.1.4): 56 data bytes

64 bytes from 24.1.1.4: icmp_seq=0 ttl=62 time=16.184 ms

64 bytes from 24.1.1.4: icmp_seq=1 ttl=62 time=1.055 ms

  1. Create another GRE port gr-1/0/0 on R3 and R4, the target logical topology, as shown below:

  R3(gr-1/0/0)----------------------------(gr-1/0/0)R4

Lo0.0 3.3.3.3/32                                      Lo0.0 4.4.4.4/32
  • GRE interface on R3
user@MX80-A> show interfaces gr-1/0/0 
Physical interface: gr-1/0/0, Enabled, Physical link is Up
  Interface index: 183, SNMP ifIndex: 1053
  Type: GRE, Link-level type: GRE, MTU: Unlimited, Speed: 100000mbps
  Device flags   : Present Running
  Interface flags: Point-To-Point SNMP-Traps
  Input rate     : 384 bps (0 pps)
  Output rate    : 0 bps (0 pps)

  Logical interface gr-1/0/0.0 (Index 341) (SNMP ifIndex 1061)
    Flags: Up Point-To-Point SNMP-Traps 0x0 IP-Header 24.1.1.4:13.1.1.3:47:df:64:00000000000b000b Encapsulation: GRE-NULL
    Copy-tos-to-outer-ip-header: Off, Copy-tos-to-outer-ip-header-transit: Off
    Gre keepalives configured: Off, Gre keepalives adjacency state: down
    Input packets : 90
    Output packets: 88
    Protocol inet, MTU: 1476
    Max nh cache: 0, New hold nh limit: 0, Curr nh cnt: 0, Curr new hold cnt: 0, NH drop cnt: 0
      Flags: Sendbcast-pkt-to-re
      Addresses, Flags: Is-Preferred Is-Primary
        Destination: 192.168.1/24, Local: 192.168.1.1, Broadcast: 192.168.1.255
    Protocol iso, MTU: 1476
      Flags: Is-Primary
  • GRE interface on R4
user@MX80-B> show interfaces gr-1/0/0 
Physical interface: gr-1/0/0, Enabled, Physical link is Up
  Interface index: 183, SNMP ifIndex: 929
  Type: GRE, Link-level type: GRE, MTU: Unlimited, Speed: 100000mbps
  Device flags   : Present Running
  Interface flags: Point-To-Point SNMP-Traps
  Input rate     : 0 bps (0 pps)
  Output rate    : 0 bps (0 pps)

  Logical interface gr-1/0/0.0 (Index 342) (SNMP ifIndex 939)
    Flags: Up Point-To-Point SNMP-Traps 0x0 IP-Header 13.1.1.3:24.1.1.4:47:df:64:0000000000080008 Encapsulation: GRE-NULL
    Copy-tos-to-outer-ip-header: Off, Copy-tos-to-outer-ip-header-transit: Off
    Gre keepalives configured: Off, Gre keepalives adjacency state: down
    Input packets : 94
    Output packets: 98
    Protocol inet, MTU: 1476
    Max nh cache: 0, New hold nh limit: 0, Curr nh cnt: 0, Curr new hold cnt: 0, NH drop cnt: 0
      Flags: Sendbcast-pkt-to-re
      Addresses, Flags: Is-Preferred Is-Primary
        Destination: 192.168.1/24, Local: 192.168.1.2, Broadcast: 192.168.1.255
    Protocol iso, MTU: 1476
      Flags: Is-Primary
  • Ping test between R3 and R4 via GRE interface gr-1/0/0
user@MX80-A> ping 192.168.1.2 source 192.168.1.1 logical-system R3 count 2 
PING 192.168.1.2 (192.168.1.2): 56 data bytes
64 bytes from 192.168.1.2: icmp_seq=0 ttl=64 time=1.158 ms
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=17.056 ms
  • ISIS neighbor between R3 and R4 via the GRE port
user@MX80-A> show isis adjacency logical-system R3 
Interface             System         L State        Hold (secs) SNPA
gr-1/0/0.0            jtac-MX80-r075-R4 2 Up                 26

user@MX80-B> show isis adjacency logical-system R4 
Interface             System         L State        Hold (secs) SNPA
gr-1/0/0.0            jtac-MX80-r073-R3 2 Up                 26
  • Ping test between R3 and R4 via the GRE port gr-1/0/0
user@MX80-A> ping 4.4.4.4 source 3.3.3.3 logical-system R3 count 2 
PING 4.4.4.4 (4.4.4.4): 56 data bytes
64 bytes from 4.4.4.4: icmp_seq=0 ttl=64 time=1.137 ms
64 bytes from 4.4.4.4: icmp_seq=1 ttl=64 time=1.031 ms

The full configuration for reference is given below:

R1

set logical-systems R1 interfaces xe-0/0/2 unit 0 family inet address 12.1.1.1/24
set logical-systems R1 interfaces gr-0/0/0 unit 0 tunnel source 1.1.1.1
set logical-systems R1 interfaces gr-0/0/0 unit 0 tunnel destination 2.2.2.2
set logical-systems R1 interfaces gr-0/0/0 unit 0 family inet address 172.16.1.1/24
set logical-systems R1 interfaces xe-0/0/0 unit 0 family inet address 13.1.1.1/24
set logical-systems R1 interfaces lo0 unit 1 family inet address 1.1.1.1/32
set logical-systems R1 protocols ospf area 0.0.0.0 interface xe-0/0/0.0 interface-type p2p
set logical-systems R1 protocols ospf area 0.0.0.0 interface gr-0/0/0.0 interface-type p2p
set logical-systems R1 routing-options static route 2.2.2.2/32 next-hop 12.1.1.2

R2

set logical-systems R2 interfaces xe-0/0/2 unit 0 family inet address 12.1.1.2/24
set logical-systems R2 interfaces gr-0/0/0 unit 0 tunnel source 2.2.2.2
set logical-systems R2 interfaces gr-0/0/0 unit 0 tunnel destination 1.1.1.1
set logical-systems R2 interfaces gr-0/0/0 unit 0 family inet address 172.16.1.2/24
set logical-systems R2 interfaces xe-0/0/0 unit 0 family inet address 24.1.1.2/24
set logical-systems R2 interfaces lo0 unit 2 family inet address 2.2.2.2/32
set logical-systems R2 protocols ospf area 0.0.0.0 interface gr-0/0/0.0 interface-type p2p
set logical-systems R2 protocols ospf area 0.0.0.0 interface xe-0/0/0.0 interface-type p2p
set logical-systems R2 routing-options static route 1.1.1.1/32 next-hop 12.1.1.1

R3

set logical-systems R3 interfaces gr-1/0/0 unit 0 tunnel source 13.1.1.3
set logical-systems R3 interfaces gr-1/0/0 unit 0 tunnel destination 24.1.1.4
set logical-systems R3 interfaces gr-1/0/0 unit 0 family inet address 192.168.1.1/24
set logical-systems R3 interfaces gr-1/0/0 unit 0 family iso
set logical-systems R3 interfaces xe-0/0/3 unit 0 family inet address 13.1.1.3/24
set logical-systems R3 interfaces lo0 unit 3 family inet address 3.3.3.3/32
set logical-systems R3 interfaces lo0 unit 3 family iso address 49.0001.3333.3333.3333.00
set logical-systems R3 protocols isis level 1 disable
set logical-systems R3 protocols isis interface gr-1/0/0.0 point-to-point
set logical-systems R3 protocols isis interface lo0.3 passive
set logical-systems R3 protocols ospf area 0.0.0.0 interface xe-0/0/3.0 interface-type p2p

R4

set logical-systems R4 interfaces gr-1/0/0 unit 0 tunnel source 24.1.1.4
set logical-systems R4 interfaces gr-1/0/0 unit 0 tunnel destination 13.1.1.3
set logical-systems R4 interfaces gr-1/0/0 unit 0 family inet address 192.168.1.2/24
set logical-systems R4 interfaces gr-1/0/0 unit 0 family iso
set logical-systems R4 interfaces xe-0/0/1 unit 0 family inet address 24.1.1.4/24
set logical-systems R4 interfaces lo0 unit 4 family inet address 4.4.4.4/32
set logical-systems R4 interfaces lo0 unit 4 family iso address 49.0001.4444.4444.4444.00
set logical-systems R4 protocols isis level 1 disable
set logical-systems R4 protocols isis interface gr-1/0/0.0 point-to-point
set logical-systems R4 protocols isis interface lo0.4 passive
set logical-systems R4 protocols ospf area 0.0.0.0 interface xe-0/0/1.0 interface-type p2p

 

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