MPLS TE FRR

Issue

In this example we will go through Normal MPLS TE configuration to establish connectivity between our CEs: R1 and R5 and then we will implement FRR and see how we can maintain our network using this feature

ISIS area 0 is the IGP used inside the backbone and static routing is the protocol implemented on CE-PE connections

Configuration

R1

R1#sh run int f1/0

interface FastEthernet1/0

 ip address 192.1.12.1 255.255.255.0

 speed 100

 duplex full

R1#sh run int lo0

interface Loopback0

 ip address 1.1.1.1 255.255.255.255

R1#sh run | sec ip route

ip route 0.0.0.0 0.0.0.0 192.1.12.2

R2

R2#sh run int f1/0

interface FastEthernet1/0

 vrf forwarding MSSK

 ip address 192.1.12.2 255.255.255.0

 speed 100

 duplex full

R2#sh run int f1/1

interface FastEthernet1/1

 ip address 192.1.23.2 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R2#sh run int f2/0

interface FastEthernet2/0

 ip address 192.1.26.2 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R2#sh run int lo0

interface Loopback0

 ip address 2.2.2.2 255.255.255.255

mpls traffic-eng tunnels

R2#sh run | sec ip expli

ip explicit-path name TO_R4 enable

 next-address 3.3.3.3

 next-address 7.7.7.7

 next-address 4.4.4.4

R2#sh run int tun0

interface Tunnel0

 ip unnumbered Loopback0

 tunnel mode mpls traffic-eng

 tunnel destination 4.4.4.4

 tunnel mpls traffic-eng autoroute announce

 tunnel mpls traffic-eng path-option 1 explicit name TO_R4

 tunnel mpls traffic-eng fast-reroute

router isis

 net 49.0001.0000.0000.0002.00

 is-type level-2-only

 metric-style wide

 passive-interface Loopback0

 mpls traffic-eng router-id Loopback0

 mpls traffic-eng level-2

R2#sh run | sec router bgp

router bgp 100

 bgp log-neighbor-changes

 no bgp default ipv4-unicast

 neighbor 4.4.4.4 remote-as 100

 neighbor 4.4.4.4 update-source Loopback0

 !

 address-family ipv4

 exit-address-family

 !

 address-family vpnv4

  neighbor 4.4.4.4 activate

  neighbor 4.4.4.4 send-community both

 exit-address-family

 !

 address-family ipv4 vrf MSSK

  network 1.1.1.1 mask 255.255.255.255

  network 192.1.12.0

 exit-address-family

R2#sh run | sec vrf def

vrf definition MSSK

 rd 100:1

 route-target export 100:1

 route-target import 100:1

 !

 address-family ipv4

 exit-address-family

ip route 1.1.1.1 255.255.255.255 192.1.12.1

R3

R3#sh run int f1/0

interface FastEthernet1/0

 ip address 192.1.23.3 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R3#sh run int f1/1

interface FastEthernet1/1

 ip address 192.1.34.3 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R3#sh run int f2/0

interface FastEthernet2/0

 ip address 192.1.36.3 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R3#sh run int f2/1

interface FastEthernet2/1

 ip address 192.1.37.3 255.255.255.0

 ip router isis

 shutdown

 speed 100

 duplex full

 mpls traffic-eng tunnels

 mpls traffic-eng backup-path Tunnel0

 ip rsvp bandwidth

R3#sh run int lo0

interface Loopback0

 ip address 3.3.3.3 255.255.255.255

R3#sh run | sec router isis

router isis

 net 49.0001.0000.0000.0003.00

 is-type level-2-only

 metric-style wide

 passive-interface Loopback0

 mpls traffic-eng router-id Loopback0

 mpls traffic-eng level-2

mpls traffic-eng tunnels

R3#sh run | sec ip expli

ip explicit-path name EX enable

 exclude-address 192.1.37.7

 exclude-address 192.1.37.3

R3#sh run int tun0

interface Tunnel0

 ip unnumbered Loopback0

 tunnel mode mpls traffic-eng

 tunnel destination 7.7.7.7

 tunnel mpls traffic-eng path-option 1 explicit name EX

R4

R4#sh run int f1/0

interface FastEthernet1/0

 vrf forwarding MSSK

 ip address 192.1.45.4 255.255.255.0

 speed 100

 duplex full

R4#sh run int f1/1

interface FastEthernet1/1

 ip address 192.1.34.4 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R4#sh run int f2/0

interface FastEthernet2/0

 ip address 192.1.47.4 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R4#sh run int lo0

interface Loopback0

 ip address 4.4.4.4 255.255.255.255

R4#sh run | sec router isis

router isis

 net 49.0001.0000.0000.0004.00

 is-type level-2-only

 metric-style wide

 passive-interface Loopback0

 mpls traffic-eng router-id Loopback0

 mpls traffic-eng level-2

R4#sh run | sec router bgp

router bgp 100

 bgp log-neighbor-changes

 no bgp default ipv4-unicast

 neighbor 2.2.2.2 remote-as 100

 neighbor 2.2.2.2 update-source Loopback0

 !

 address-family ipv4

 exit-address-family

 !

 address-family vpnv4

  neighbor 2.2.2.2 activate

  neighbor 2.2.2.2 send-community both

 exit-address-family

 !

 address-family ipv4 vrf MSSK

  network 5.5.5.5 mask 255.255.255.255

  network 192.1.45.0

 exit-address-family

mpls traffic-eng tunnels

R4#sh run | sec vrf def

vrf definition MSSK

 rd 100:1

 route-target export 100:1

 route-target import 100:1

 !

 address-family ipv4

 exit-address-family

R4#sh run int tun0

interface Tunnel0

 ip unnumbered Loopback0

 tunnel mode mpls traffic-eng

 tunnel destination 2.2.2.2

 tunnel mpls traffic-eng autoroute announce

 tunnel mpls traffic-eng path-option 1 explicit name TO_R2

 tunnel mpls traffic-eng fast-reroute

R4#sh run | sec ip expli

ip explicit-path name TO_R2 enable

 next-address 7.7.7.7

 next-address 6.6.6.6

 next-address 2.2.2.2

R4#sh run | sec ip route

ip route vrf MSSK 5.5.5.5 255.255.255.255 192.1.45.5

R5

R5#sh run int f1/0

interface FastEthernet1/0

 ip address 192.1.45.5 255.255.255.0

 speed 100

 duplex full

R5#sh run int lo0

interface Loopback0

 ip address 5.5.5.5 255.255.255.255

R5#sh run | sec ip route

ip route 0.0.0.0 0.0.0.0 192.1.45.4

R6

R6#sh run int f1/0

interface FastEthernet1/0

 ip address 192.1.26.6 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R6#sh run int f1/1

interface FastEthernet1/1

 ip address 192.1.67.6 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R6#sh run int f2/0

interface FastEthernet2/0

 ip address 192.1.36.6 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R6#sh run int lo0

interface Loopback0

 ip address 6.6.6.6 255.255.255.255

mpls traffic-eng tunnels

R6#sh run | sec router isis

router isis

 net 49.0001.0000.0000.0006.00

 is-type level-2-only

 metric-style wide

 passive-interface Loopback0

 mpls traffic-eng router-id Loopback0

 mpls traffic-eng level-2

R7

R7#sh run int f1/0

interface FastEthernet1/0

 ip address 192.1.47.7 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R7#sh run int f1/1

interface FastEthernet1/1

 ip address 192.1.67.7 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 mpls traffic-eng backup-path Tunnel0

 ip rsvp bandwidth

R7#sh run int f2/0

interface FastEthernet2/0

 ip address 192.1.37.7 255.255.255.0

 ip router isis

 speed 100

 duplex full

 mpls traffic-eng tunnels

 ip rsvp bandwidth

R7#sh run int lo0

interface Loopback0

 ip address 7.7.7.7 255.255.255.255

mpls traffic-eng tunnels

R7#sh run | sec router isis

router isis

 net 49.0001.0000.0000.0007.00

 is-type level-2-only

 metric-style wide

 passive-interface Loopback0

 mpls traffic-eng router-id Loopback0

 mpls traffic-eng level-2

R7#sh run int tun0

interface Tunnel0

 ip unnumbered Loopback0

 tunnel mode mpls traffic-eng

 tunnel destination 6.6.6.6

 tunnel mpls traffic-eng path-option 1 explicit name EX

R7#sh run | sec ip expli

ip explicit-path name EX enable

 exclude-address 192.1.67.6

 exclude-address 192.1.67.7

 

Verification

R1#sh ip route 0.0.0.0

Routing entry for 0.0.0.0/0, supernet

  Known via "static", distance 1, metric 0, candidate default path

  Routing Descriptor Blocks:

  * 192.1.12.2

      Route metric is 0, traffic share count is 1

R1#ping 5.5.5.5 source lo0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 24/28/44 ms

R1#traceroute 5.5.5.5 source lo0

Type escape sequence to abort.

Tracing the route to 5.5.5.5

VRF info: (vrf in name/id, vrf out name/id)

  1 192.1.12.2 4 msec 4 msec 4 msec

  2 192.1.23.3 [MPLS: Labels 17/16 Exp 0] 28 msec 24 msec 24 msec

  3 192.1.37.7 [MPLS: Labels 17/16 Exp 0] 28 msec 24 msec 24 msec

  4 192.1.45.4 [MPLS: Label 16 Exp 0] 24 msec 20 msec 20 msec

  5 192.1.45.5 28 msec 24 msec *

As can be seen that the packet is following the explicit path configured

Now, on R2 we can see that the Fast Reroute Protection is requested

R2#sh mpls traffic-eng tunnels protection

P2P TUNNELS:

R2_t0

  LSP Head, Tunnel0, Admin: up, Oper: up

  Src 2.2.2.2, Dest 4.4.4.4, Instance 200

  Fast Reroute Protection: Requested

    Outbound: Unprotected: no backup tunnel assigned

      LSP signalling info:

        Original: out i/f: Fa1/1, label: 17, nhop: 192.1.23.3

                  nnhop: 7.7.7.7; nnhop rtr id: 7.7.7.7

  Path Protection: None

P2MP TUNNELS:

Now, let us shutdown the interface connecting R3 to R7 (Which is supposed to be a link in the explicit path)

R3(config)#interface fastEthernet 2/1

R3(config-if)#shutdown

Now, let us trace again from R1 to R5 loopback 0 interface

R1#traceroute 5.5.5.5 source lo0

Type escape sequence to abort.

Tracing the route to 5.5.5.5

VRF info: (vrf in name/id, vrf out name/id)

  1 192.1.12.2 16 msec 4 msec 4 msec

  2 192.1.23.3 [MPLS: Labels 17/16 Exp 0] 28 msec 28 msec 24 msec

  3 192.1.34.4 [MPLS: Labels 18/17/16 Exp 0] 44 msec 24 msec 28 msec

  4 192.1.47.7 [MPLS: Labels 17/16 Exp 0] 28 msec 24 msec 28 msec

  5 192.1.45.4 [MPLS: Label 16 Exp 0] 24 msec 24 msec 24 msec

  6 192.1.45.5 28 msec 24 msec *

We can see that an additional label has been added as the link which is supposed to be in the explicit path is now broken

Also noticed that the packet get back again to R4 even though it can be logically asked why not to go to R4 directly? Because the packet is following the explicit path

R3#sh mpls traffic-eng fast-reroute database

P2P Headend FRR information:

Protected tunnel               In-label Out intf/label   FRR intf/label   Status

---------------------------    -------- --------------   --------------   ------

P2P LSP midpoint frr information:

LSP identifier                 In-label Out intf/label   FRR intf/label   Status

---------------------------    -------- --------------   --------------   ------

2.2.2.2 0 [200]                17       Fa2/1:17         Tu0:17           active

P2MP Sub-LSP FRR information:

*Sub-LSP identifier

src_lspid[subid]->dst_tunid    In-label Out intf/label   FRR intf/label   Status

---------------------------    -------- --------------   --------------   ------

* Sub-LSP identifier format: <TunSrc>_<LSP_ID>[SubgroupID]-><TunDst>_<Tun_ID>

  Note: Sub-LSP identifier may be truncated.

  Use 'detail' display for the complete key