Merge pull request #977 from fett0/sr-mpls-correction

Segment-rounting : Add documentation about segment-routing mpls on VyOS

5 files changed, 638 insertions, 0 deletions

diff --git a/docs/_static/images/vyos-sr-isis.png b/docs/_static/images/vyos-sr-isis.png
new file mode 100644
index 00000000..62430919
--- /dev/null
+++ b/docs/_static/images/vyos-sr-isis.png
diff --git a/docs/configexamples/index.rst b/docs/configexamples/index.rst
index a53a86c6..b3610d3a 100644
--- a/docs/configexamples/index.rst
+++ b/docs/configexamples/index.rst
@@ -20,6 +20,7 @@ This chapter contains various configuration examples:
    inter-vrf-routing-vrf-lite
    openvpn-ldap
    qos
+   segment-routing-isis
    nmp
 
 
diff --git a/docs/configexamples/segment-routing-isis.rst b/docs/configexamples/segment-routing-isis.rst
new file mode 100644
index 00000000..d9bc439b
--- /dev/null
+++ b/docs/configexamples/segment-routing-isis.rst
@@ -0,0 +1,279 @@
+:lastproofread: 2023-04-10
+
+.. _examples-segment-routing-isis:
+
+#############################
+Segment-routing IS-IS example
+#############################
+
+When utilizing VyOS in an environment with Cisco IOS-XR gear you can use this 
+blue print as an initial setup to get MPLS ISIS-SR working between those two 
+devices.The lab was build using :abbr:`EVE-NG (Emulated Virtual
+Environment NG)`.
+
+.. figure:: /_static/images/vyos-sr-isis.png
+   :alt: ISIS-SR network
+
+   ISIS-SR example network
+
+The below configuration is used as example where we keep focus on 
+VyOS-P1/VyOS-P2/XRv-P3 which we share the settings.
+
+
+Configuration
+=============
+
+- VyOS-P1:
+
+.. code-block:: none
+
+  set interfaces dummy dum0 address '192.0.2.1/32'
+  set interfaces ethernet eth1 address '192.0.2.5/30'
+  set interfaces ethernet eth1 mtu '8000'
+  set interfaces ethernet eth3 address '192.0.2.21/30'
+  set interfaces ethernet eth3 mtu '8000'
+  set protocols isis interface dum0 passive
+  set protocols isis interface eth1 network point-to-point
+  set protocols isis interface eth3 network point-to-point
+  set protocols isis level 'level-2'
+  set protocols isis log-adjacency-changes
+  set protocols isis metric-style 'wide'
+  set protocols isis net '49.0000.0000.0000.0001.00'
+  set protocols isis segment-routing maximum-label-depth '8'
+  set protocols isis segment-routing prefix 192.0.2.1/32 index value '1'
+  set protocols mpls interface 'eth1'
+  set protocols mpls interface 'eth3'
+  set system host-name 'P1-VyOS'
+
+- XRv-P3:
+
+.. code-block:: none
+
+  hostname P3-VyOS
+  interface Loopback0
+   ipv4 address 192.0.2.3 255.255.255.255
+  !
+  interface GigabitEthernet0/0/0/1
+   mtu 8014
+   ipv4 address 192.0.2.6 255.255.255.252
+  !
+  interface GigabitEthernet0/0/0/2
+   mtu 8014
+   ipv4 address 192.0.2.18 255.255.255.252
+  !
+  router isis VyOS
+   is-type level-2-only
+   net 49.0000.0000.0000.0003.00
+   log adjacency changes
+   address-family ipv4 unicast
+    metric-style wide
+    segment-routing mpls
+   !
+   interface Loopback0
+    passive
+    address-family ipv4 unicast
+     prefix-sid index 3
+    !
+   !
+   interface GigabitEthernet0/0/0/1
+    point-to-point
+    address-family ipv4 unicast
+    !
+   !
+   interface GigabitEthernet0/0/0/2
+    point-to-point
+    address-family ipv4 unicast
+    !
+   !
+  !
+
+- VyOS-P2:
+
+.. code-block:: none
+  
+  set interfaces dummy dum0 address '192.0.2.2/32'
+  set interfaces ethernet eth2 address '192.0.2.17/30'
+  set interfaces ethernet eth2 mtu '8000'
+  set interfaces ethernet eth3 address '192.0.2.26/30'
+  set interfaces ethernet eth3 mtu '8000'
+  set protocols isis interface dum0 passive
+  set protocols isis interface eth2 network point-to-point
+  set protocols isis interface eth3 network point-to-point
+  set protocols isis level 'level-2'
+  set protocols isis log-adjacency-changes
+  set protocols isis metric-style 'wide'
+  set protocols isis net '49.0000.0000.0000.0002.00'
+  set protocols isis segment-routing maximum-label-depth '8'
+  set protocols isis segment-routing prefix 192.0.2.2/32 index value '2'
+  set protocols mpls interface 'eth2'
+  set protocols mpls interface 'eth3'
+  set system host-name 'P2-VyOS'
+
+This gives us MPLS segment routing enabled and labels forwarding :
+
+.. code-block:: none
+  
+   vyos@P1-VyOS:~$ show mpls table
+   Inbound Label  Type        Nexthop               Outbound Label
+   -----------------------------------------------------------------
+   15000          SR (IS-IS)  192.0.2.6             implicit-null
+   15001          SR (IS-IS)  192.0.2.22            implicit-null
+   15002          SR (IS-IS)  fe80::5200:ff:fe04:3  implicit-null
+   16002          SR (IS-IS)  192.0.2.6             16002
+   16003          SR (IS-IS)  192.0.2.6             implicit-null
+   16011          SR (IS-IS)  192.0.2.22            implicit-null
+  
+   vyos@P2-VyOS:~$ show mpls table
+   Inbound Label  Type        Nexthop     Outbound Label
+   -------------------------------------------------------
+   15000          SR (IS-IS)  192.0.2.18  implicit-null
+   16001          SR (IS-IS)  192.0.2.18  16001
+   16003          SR (IS-IS)  192.0.2.18  implicit-null
+   16011          SR (IS-IS)  192.0.2.18  16011
+
+   RP/0/0/CPU0:P3-VyOS#show mpls forwarding
+   Tue Mar 28 17:47:18.928 UTC
+   Local  Outgoing    Prefix             Outgoing     Next Hop        Bytes
+   Label  Label       or ID              Interface                    Switched
+   ------ ----------- ------------------ ------------ --------------- ------------
+   16001  Pop         SR Pfx (idx 1)     Gi0/0/0/1    192.0.2.5       0
+   16002  Pop         SR Pfx (idx 2)     Gi0/0/0/2    192.0.2.17      0
+   16011  16011       SR Pfx (idx 11)    Gi0/0/0/1    192.0.2.5       0
+   24000  Pop         SR Adj (idx 1)     Gi0/0/0/1    192.0.2.5       0
+   24001  Pop         SR Adj (idx 3)     Gi0/0/0/1    192.0.2.5       0
+   24002  Pop         SR Adj (idx 1)     Gi0/0/0/2    192.0.2.17      0
+   24003  Pop         SR Adj (idx 3)     Gi0/0/0/2    192.0.2.17      0
+
+
+VyOS is able to check MSD per devices: 
+
+.. code-block:: none
+
+   vyos@P1-VyOS:~$ show isis segment-routing node
+   Area VyOS:
+   IS-IS L1 SR-Nodes:
+  
+   IS-IS L2 SR-Nodes:
+  
+   System ID       SRGB           SRLB            Algorithm  MSD
+   ---------------------------------------------------------------
+   0000.0000.0001  16000 - 23999  15000 - 15999   SPF        8
+   0000.0000.0002  16000 - 23999  15000 - 15999   SPF        8
+   0000.0000.0003  16000 - 23999  0 - 4294967295  SPF        10
+   0000.0000.0011  16000 - 23999  15000 - 15999   SPF        8
+
+   vyos@P2-VyOS:~$ show isis segment-routing node
+   Area VyOS:
+    IS-IS L1 SR-Nodes:
+   
+    IS-IS L2 SR-Nodes:
+   
+    System ID       SRGB           SRLB            Algorithm  MSD
+    ---------------------------------------------------------------
+    0000.0000.0001  16000 - 23999  15000 - 15999   SPF        8
+    0000.0000.0002  16000 - 23999  15000 - 15999   SPF        8
+    0000.0000.0003  16000 - 23999  0 - 4294967295  SPF        10
+    0000.0000.0011  16000 - 23999  15000 - 15999   SPF        8
+
+Here is the routing tables showing the MPLS segment routing label operations:
+
+.. code-block:: none
+
+   vyos@P1-VyOS:~$ show ip route isis
+   Codes: K - kernel route, C - connected, S - static, R - RIP,
+          O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
+          T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
+          f - OpenFabric,
+          > - selected route, * - FIB route, q - queued, r - rejected, b - backup
+          t - trapped, o - offload failure
+   
+   I>* 192.0.2.2/32 [115/30] via 192.0.2.6, eth1, label 16002, weight 1, 1d03h18m
+   I>* 192.0.2.3/32 [115/10] via 192.0.2.6, eth1, label implicit-null, weight 1, 1d03h18m
+   I   192.0.2.4/30 [115/20] via 192.0.2.6, eth1 inactive, weight 1, 1d03h18m
+   I>* 192.0.2.11/32 [115/20] via 192.0.2.22, eth3, label implicit-null, weight 1, 1d02h47m
+   I>* 192.0.2.16/30 [115/20] via 192.0.2.6, eth1, weight 1, 1d03h18m
+   I   192.0.2.20/30 [115/20] via 192.0.2.22, eth3 inactive, weight 1, 1d02h48m
+   I>* 192.0.2.24/30 [115/30] via 192.0.2.6, eth1, weight 1, 1d03h18m
+   
+   
+   vyos@P2-VyOS:~$ show ip route isis
+   Codes: K - kernel route, C - connected, S - static, R - RIP,
+          O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
+          T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
+          f - OpenFabric,
+          > - selected route, * - FIB route, q - queued, r - rejected, b - backup
+          t - trapped, o - offload failure
+   
+   I>* 192.0.2.1/32 [115/30] via 192.0.2.18, eth2, label 16001, weight 1, 1d03h17m
+   I>* 192.0.2.3/32 [115/10] via 192.0.2.18, eth2, label implicit-null, weight 1, 1d03h17m
+   I>* 192.0.2.4/30 [115/20] via 192.0.2.18, eth2, weight 1, 1d03h17m
+   I>* 192.0.2.11/32 [115/40] via 192.0.2.18, eth2, label 16011, weight 1, 1d02h47m
+   I   192.0.2.16/30 [115/20] via 192.0.2.18, eth2 inactive, weight 1, 1d03h17m
+   I>* 192.0.2.20/30 [115/30] via 192.0.2.18, eth2, weight 1, 1d03h17m
+   
+   RP/0/0/CPU0:P3-VyOS#show route isis
+   Tue Mar 28 18:19:16.417 UTC
+   
+   i L2 192.0.2.1/32 [115/20] via 192.0.2.5, 1d03h, GigabitEthernet0/0/0/1
+   i L2 192.0.2.2/32 [115/20] via 192.0.2.17, 1d03h, GigabitEthernet0/0/0/2
+   i L2 192.0.2.11/32 [115/30] via 192.0.2.5, 1d02h, GigabitEthernet0/0/0/1
+   i L2 192.0.2.20/30 [115/20] via 192.0.2.5, 1d03h, GigabitEthernet0/0/0/1
+   i L2 192.0.2.24/30 [115/20] via 192.0.2.17, 1d03h, GigabitEthernet0/0/0/2
+
+Information about prefix-sid and label-operation from VyOS
+
+.. code-block:: none
+
+   vyos@P1-VyOS:~$ show isis route prefix-sid
+   Area VyOS:
+   IS-IS L2 IPv4 routing table:
+   
+    Prefix         Metric  Interface  Nexthop    SID  Label Op.
+    ----------------------------------------------------------------------
+    192.0.2.1/32   0       -          -          -    -
+    192.0.2.2/32   30      eth1       192.0.2.6  2    Swap(16002, 16002)
+    192.0.2.3/32   10      eth1       192.0.2.6  3    Pop(16003)
+    192.0.2.4/30   20      eth1       192.0.2.6  -    -
+    192.0.2.16/30  20      eth1       192.0.2.6  -    -
+    192.0.2.20/30  0       -          -          -    -
+    192.0.2.24/30  30      eth1       192.0.2.6  -    -
+
+    vyos@P2-VyOS:~$ show isis route prefix-sid
+    Area VyOS:
+    IS-IS L2 IPv4 routing table:
+    
+     Prefix         Metric  Interface  Nexthop     SID  Label Op.
+     -----------------------------------------------------------------------
+     192.0.2.1/32   30      eth2       192.0.2.18  1    Swap(16001, 16001)
+     192.0.2.2/32   0       -          -           -    -
+     192.0.2.3/32   10      eth2       192.0.2.18  3    Pop(16003)
+     192.0.2.4/30   20      eth2       192.0.2.18  -    -
+     192.0.2.16/30  20      eth2       192.0.2.18  -    -
+     192.0.2.20/30  30      eth2       192.0.2.18  -    -
+     192.0.2.24/30  0       -          -           -    -
+
+Ping between VyOS-P1 / VyOS-P2 to confirm reachability:
+
+.. code-block:: none
+
+   vyos@P1-VyOS:~$ ping 192.0.2.2 source-address 192.0.2.1
+   PING 192.0.2.2 (192.0.2.2) from 192.0.2.1 : 56(84) bytes of data.
+   64 bytes from 192.0.2.2: icmp_seq=1 ttl=63 time=3.47 ms
+   64 bytes from 192.0.2.2: icmp_seq=2 ttl=63 time=2.06 ms
+   64 bytes from 192.0.2.2: icmp_seq=3 ttl=63 time=3.90 ms
+   64 bytes from 192.0.2.2: icmp_seq=4 ttl=63 time=3.87 ms
+   ^C
+   --- 192.0.2.2 ping statistics ---
+   4 packets transmitted, 4 received, 0% packet loss, time 3004ms
+   rtt min/avg/max/mdev = 2.064/3.326/3.903/0.748 ms
+
+   vyos@P2-VyOS:~$ ping 192.0.2.1 source-address 192.0.2.2
+   PING 192.0.2.1 (192.0.2.1) from 192.0.2.2 : 56(84) bytes of data.
+   64 bytes from 192.0.2.1: icmp_seq=1 ttl=63 time=2.91 ms
+   64 bytes from 192.0.2.1: icmp_seq=2 ttl=63 time=3.23 ms
+   64 bytes from 192.0.2.1: icmp_seq=3 ttl=63 time=2.91 ms
+   64 bytes from 192.0.2.1: icmp_seq=4 ttl=63 time=2.85 ms
+   ^C
+   --- 192.0.2.1 ping statistics ---
+   4 packets transmitted, 4 received, 0% packet loss, time 3005ms
+   rtt min/avg/max/mdev = 2.846/2.972/3.231/0.151 ms
\ No newline at end of file
diff --git a/docs/configuration/protocols/index.rst b/docs/configuration/protocols/index.rst
index 682390d5..29dc230f 100644
--- a/docs/configuration/protocols/index.rst
+++ b/docs/configuration/protocols/index.rst
@@ -14,6 +14,7 @@ Protocols
    igmp
    isis
    mpls
+   segment-routing
    ospf
    rip
    rpki
diff --git a/docs/configuration/protocols/segment-routing.rst b/docs/configuration/protocols/segment-routing.rst
new file mode 100644
index 00000000..5ee710e9
--- /dev/null
+++ b/docs/configuration/protocols/segment-routing.rst
@@ -0,0 +1,357 @@
+.. _segment-routing:
+
+###############
+Segment Routing
+###############
+
+Segment Routing (SR) is a network architecture that is similar to source-routing
+. In this architecture, the ingress router adds a list of segments, known as 
+SIDs, to the packet as it enters the network. These segments represent different 
+portions of the network path that the packet will take.
+
+The SR segments are portions of the network path taken by the packet, and are 
+called SIDs. At each node, the first SID of the list is read, executed as a 
+forwarding function, and may be popped to let the next node read the next SID of 
+the list. The SID list completely determines the path where the packet is 
+forwarded.
+
+Segment Routing can be applied to an existing MPLS-based data plane and defines
+a control plane network architecture. In MPLS networks, segments are encoded as
+MPLS labels and are added at the ingress router. These MPLS labels are then 
+exchanged and populated by Interior Gateway Protocols (IGPs) like IS-IS or OSPF 
+which are running on most ISPs.
+
+
+.. note:: Segment routing defines a control plane network architecture and
+  can be applied to an existing MPLS based dataplane. In the MPLS networks,
+  segments are encoded as MPLS labels and are imposed at the ingress router.
+  MPLS labels are exchanged and populated by IGPs like IS-IS.Segment Routing
+  as per RFC8667 for MPLS dataplane. It supports IPv4, IPv6 and ECMP and has
+  been tested against Cisco & Juniper routers.however,this deployment is still
+  EXPERIMENTAL for FRR.
+ 
+
+IS-IS SR Configuration
+----------------------
+
+Segment routing (SR) is used by the IGP protocols to interconnect network
+devices, below configuration shows how to enable SR on IS-IS:
+
+
+.. note:: ``Known limitations:`` 
+
+  No support for level redistribution (L1 to L2 or L2 to L1)
+
+  No support for binding SID
+
+  No support for SRLB
+
+  Only one SRGB and default SPF Algorithm is supported
+
+
+
+.. cfgcmd::  set protocols isis segment-routing global-block high-label-value 
+  <label-value>
+
+  Set the Segment Routing Global Block i.e. the label range used by MPLS to 
+  store label in the MPLS FIB for Prefix SID. Note that the block size may 
+  not exceed 65535.
+
+.. cfgcmd:: set protocols isis segment-routing global-block low-label-value 
+  <label-value>
+
+  Set the Segment Routing Global Block i.e. the low label range used by MPLS to 
+  store label in the MPLS FIB for Prefix SID. Note that the block size may 
+  not exceed 65535.
+ 
+.. cfgcmd:: set protocols isis segment-routing local-block high-label-value 
+  <label-value>
+
+  Set the Segment Routing Local Block i.e. the label range used by MPLS to 
+  store label in the MPLS FIB for Prefix SID. Note that the block size may 
+  not exceed 65535.Segment Routing Local Block, The negative command always 
+  unsets both.
+
+.. cfgcmd:: set protocols isis segment-routing local-block <low-label-value 
+  <label-value>
+
+  Set the Segment Routing Local Block i.e. the low label range used by MPLS to 
+  store label in the MPLS FIB for Prefix SID. Note that the block size may 
+  not exceed 65535.Segment Routing Local Block, The negative command always 
+  unsets both.
+
+.. cfgcmd:: set protocols isis segment-routing maximum-label-depth <1-16>
+
+  Set the Maximum Stack Depth supported by the router. The value depend of
+  the MPLS dataplane.
+
+.. cfgcmd:: set protocols isis segment-routing prefix <address> index value 
+  <0-65535>
+   
+  A segment ID that contains an IP address prefix calculated by an IGP in the
+  service provider core network. Prefix SIDs are globally unique, this value
+  indentify it 
+
+.. cfgcmd:: set protocols isis segment-routing prefix <address> index
+   <no-php-flag | explicit-null| n-flag-clear>
+
+   this option allows to configure prefix-sid on SR. The ‘no-php-flag’ means NO 
+   Penultimate Hop Popping that allows SR node to request to its neighbor to 
+   not pop the label. The ‘explicit-null’ flag allows SR node to request to its 
+   neighbor to send IP packet with the EXPLICIT-NULL label. The ‘n-flag-clear’ 
+   option can be used to explicitly clear the Node flag that is set by default 
+   for Prefix-SIDs associated to loopback addresses. This option is necessary 
+   to configure Anycast-SIDs.
+
+
+.. opcmd:: show isis segment-routing node
+ 
+   Show detailed information about all learned Segment Routing Nodes
+
+.. opcmd:: show isis route prefix-sid
+
+   Show detailed information about prefix-sid and label learned
+
+.. note:: more information related IGP  - :ref:`routing-isis`
+
+   
+
+OSPF SR  Configuration
+----------------------
+
+Segment routing (SR) is used by the IGP protocols to interconnect network
+devices, below configuration shows how to enable SR on OSPF:
+
+.. cfgcmd:: set protocols ospf parameters opaque-lsa
+
+  Enable the Opaque-LSA capability (rfc2370), necessary to transport label 
+  on IGP
+
+
+.. cfgcmd:: set protocols ospf segment-routing global-block high-label-value 
+  <label-value>
+
+  Set the Segment Routing Global Block i.e. the label range used by MPLS to 
+  store label in the MPLS FIB for Prefix SID. Note that the block size may 
+  not exceed 65535.
+
+.. cfgcmd:: set protocols ospf segment-routing global-block low-label-value 
+  <label-value>
+
+  Set the Segment Routing Global Block i.e. the low label range used by MPLS to 
+  store label in the MPLS FIB for Prefix SID. Note that the block size may 
+  not exceed 65535.
+
+.. cfgcmd:: set protocols ospf segment-routing local-block high-label-value 
+  <label-value>
+
+  Set the Segment Routing Local Block i.e. the label range used by MPLS to 
+  store label in the MPLS FIB for Prefix SID. Note that the block size may 
+  not exceed 65535.Segment Routing Local Block, The negative command always 
+  unsets both.
+
+.. cfgcmd:: set protocols ospf segment-routing local-block <low-label-value 
+  <label-value>
+
+  Set the Segment Routing Local Block i.e. the low label range used by MPLS to 
+  store label in the MPLS FIB for Prefix SID. Note that the block size may 
+  not exceed 65535.Segment Routing Local Block, The negative command always 
+  unsets both.
+
+.. cfgcmd:: set protocols ospf segment-routing maximum-label-depth <1-16>
+
+  Set the Maximum Stack Depth supported by the router. The value depend of
+  the MPLS dataplane.
+
+.. cfgcmd:: set protocols ospf segment-routing prefix <address> index value 
+  <0-65535>
+   
+  A segment ID that contains an IP address prefix calculated by an IGP in the
+  service provider core network. Prefix SIDs are globally unique, this value
+  indentify it 
+
+.. cfgcmd:: set protocols ospf segment-routing prefix <address> index
+   <no-php-flag | explicit-null| n-flag-clear>
+
+   this option allows to configure prefix-sid on SR. The ‘no-php-flag’ means NO 
+   Penultimate Hop Popping that allows SR node to request to its neighbor to 
+   not pop the label. The ‘explicit-null’ flag allows SR node to request to its 
+   neighbor to send IP packet with the EXPLICIT-NULL label. The ‘n-flag-clear’ 
+   option can be used to explicitly clear the Node flag that is set by default 
+   for Prefix-SIDs associated to loopback addresses. This option is necessary 
+   to configure Anycast-SIDs.
+
+.. note:: more information related IGP  - :ref:`routing-ospf`
+
+Configuration Example
+---------------------
+
+we described the configuration SR ISIS / SR OSPF using 2 connected with them to
+share label information.
+
+Enable IS-IS with Segment Routing (Experimental)
+================================================
+
+**Node 1:**
+
+.. code-block:: none
+
+  set interfaces loopback lo address '192.168.255.255/32'
+  set interfaces ethernet eth1 address '192.0.2.1/24'
+
+  set protocols isis interface eth1
+  set protocols isis interface lo
+  set protocols isis net '49.0001.1921.6825.5255.00'
+  set protocols isis segment-routing global-block high-label-value '599'
+  set protocols isis segment-routing global-block low-label-value '550'
+  set protocols isis segment-routing prefix 192.168.255.255/32 index value '1'
+  set protocols isis segment-routing prefix 192.168.255.255/32 index explicit-null
+  set protocols mpls interface 'eth1'
+  
+**Node 2:**
+
+.. code-block:: none
+
+  set interfaces loopback lo address '192.168.255.254/32'
+  set interfaces ethernet eth1 address '192.0.2.2/24'
+
+  set protocols isis interface eth1
+  set protocols isis interface lo
+  set protocols isis net '49.0001.1921.6825.5254.00'
+  set protocols isis segment-routing global-block high-label-value '599'
+  set protocols isis segment-routing global-block low-label-value '550'
+  set protocols isis segment-routing prefix 192.168.255.254/32 index value '2'
+  set protocols isis segment-routing prefix 192.168.255.254/32 index explicit-null
+  set protocols mpls interface 'eth1'
+  
+  
+  
+This gives us MPLS segment routing enabled and labels for far end loopbacks:
+
+.. code-block:: none
+
+  Node-1@vyos:~$ show mpls table
+   Inbound Label  Type        Nexthop                Outbound Label
+   ----------------------------------------------------------------------
+   552            SR (IS-IS)  192.0.2.2              IPv4 Explicit Null <-- Node-2 loopback learned on Node-1
+   15000          SR (IS-IS)  192.0.2.2              implicit-null
+   15001          SR (IS-IS)  fe80::e87:6cff:fe09:1  implicit-null
+   15002          SR (IS-IS)  192.0.2.2              implicit-null
+   15003          SR (IS-IS)  fe80::e87:6cff:fe09:1  implicit-null
+
+  Node-2@vyos:~$ show mpls table
+   Inbound Label  Type        Nexthop               Outbound Label
+   ---------------------------------------------------------------------
+   551            SR (IS-IS)  192.0.2.1             IPv4 Explicit Null <-- Node-1 loopback learned on Node-2
+   15000          SR (IS-IS)  192.0.2.1             implicit-null
+   15001          SR (IS-IS)  fe80::e33:2ff:fe80:1  implicit-null
+   15002          SR (IS-IS)  192.0.2.1             implicit-null
+   15003          SR (IS-IS)  fe80::e33:2ff:fe80:1  implicit-null
+
+Here is the routing tables showing the MPLS segment routing label operations:
+
+.. code-block:: none
+
+  Node-1@vyos:~$ show ip route isis
+  Codes: K - kernel route, C - connected, S - static, R - RIP,
+         O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
+         T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
+         f - OpenFabric,
+         > - selected route, * - FIB route, q - queued, r - rejected, b - backup
+         t - trapped, o - offload failure
+
+  I   192.0.2.0/24 [115/20] via 192.0.2.2, eth1 inactive, weight 1, 00:07:48
+  I>* 192.168.255.254/32 [115/20] via 192.0.2.2, eth1, label IPv4 Explicit Null, weight 1, 00:03:39
+
+  Node-2@vyos:~$ show ip route isis
+  Codes: K - kernel route, C - connected, S - static, R - RIP,
+         O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
+         T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
+         f - OpenFabric,
+         > - selected route, * - FIB route, q - queued, r - rejected, b - backup
+         t - trapped, o - offload failure
+
+  I   192.0.2.0/24 [115/20] via 192.0.2.1, eth1 inactive, weight 1, 00:07:46
+  I>* 192.168.255.255/32 [115/20] via 192.0.2.1, eth1, label IPv4 Explicit Null, weight 1, 00:03:43
+
+
+Enable OSPF with Segment Routing (Experimental):
+================================================
+
+**Node 1**
+
+.. code-block:: none
+
+  set interfaces loopback lo address 10.1.1.1/32
+  set interfaces ethernet eth0 address 192.168.0.1/24
+  set protocols ospf area 0 network '192.168.0.0/24'
+  set protocols ospf area 0 network '10.1.1.1/32'
+  set protocols ospf parameters opaque-lsa
+  set protocols ospf parameters router-id '10.1.1.1'
+  set protocols ospf segment-routing global-block high-label-value '1100'
+  set protocols ospf segment-routing global-block low-label-value '1000'
+  set protocols ospf segment-routing prefix 10.1.1.1/32 index explicit-null
+  set protocols ospf segment-routing prefix 10.1.1.1/32 index value '1'
+
+**Node 2**
+
+.. code-block:: none
+
+  set interfaces loopback lo address 10.1.1.2/32
+  set interfaces ethernet eth0 address 192.168.0.2/24
+  set protocols ospf area 0 network '192.168.0.0/24'
+  set protocols ospf area 0 network '10.1.1.2/32'
+  set protocols ospf parameters opaque-lsa
+  set protocols ospf parameters router-id '10.1.1.2'
+  set protocols ospf segment-routing global-block high-label-value '1100'
+  set protocols ospf segment-routing global-block low-label-value '1000'
+  set protocols ospf segment-routing prefix 10.1.1.2/32 index explicit-null
+  set protocols ospf segment-routing prefix 10.1.1.2/32 index value '2'
+
+
+This gives us MPLS segment routing enabled and labels for far end loopbacks:
+
+.. code-block:: none
+
+  Node-1@vyos:~$ show mpls table
+   Inbound Label  Type       Nexthop      Outbound Label
+   -----------------------------------------------------------
+   1002           SR (OSPF)  192.168.0.2  IPv4 Explicit Null  <-- Node-2 loopback learned on Node-1
+   15000          SR (OSPF)  192.168.0.2  implicit-null
+   15001          SR (OSPF)  192.168.0.2  implicit-null
+
+  Node-2@vyos:~$ show mpls table
+   Inbound Label  Type       Nexthop      Outbound Label
+   -----------------------------------------------------------
+   1001           SR (OSPF)  192.168.0.1  IPv4 Explicit Null  <-- Node-1 loopback learned on Node-2
+   15000          SR (OSPF)  192.168.0.1  implicit-null
+   15001          SR (OSPF)  192.168.0.1  implicit-null
+
+Here is the routing tables showing the MPLS segment routing label operations:
+
+.. code-block:: none
+
+  Node-1@vyos:~$ show ip route ospf
+  Codes: K - kernel route, C - connected, S - static, R - RIP,
+         O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
+         T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
+         f - OpenFabric,
+         > - selected route, * - FIB route, q - queued, r - rejected, b - backup
+         t - trapped, o - offload failure
+
+  O   10.1.1.1/32 [110/0] is directly connected, lo, weight 1, 00:03:43
+  O>* 10.1.1.2/32 [110/1] via 192.168.0.2, eth0, label IPv4 Explicit Null, weight 1, 00:03:32
+  O   192.168.0.0/24 [110/1] is directly connected, eth0, weight 1, 00:03:43
+
+  Node-2@vyos:~$ show ip route ospf
+  Codes: K - kernel route, C - connected, S - static, R - RIP,
+         O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
+         T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
+         f - OpenFabric,
+         > - selected route, * - FIB route, q - queued, r - rejected, b - backup
+         t - trapped, o - offload failure
+
+  O>* 10.1.1.1/32 [110/1] via 192.168.0.1, eth0, label IPv4 Explicit Null, weight 1, 00:03:36
+  O   10.1.1.2/32 [110/0] is directly connected, lo, weight 1, 00:03:51
+  O   192.168.0.0/24 [110/1] is directly connected, eth0, weight 1, 00:03:51
+