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diff --git a/docs/configuration/protocols/segment-routing.md b/docs/configuration/protocols/segment-routing.md new file mode 100644 index 00000000..af47d343 --- /dev/null +++ b/docs/configuration/protocols/segment-routing.md @@ -0,0 +1,359 @@ +(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 +identify 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 +identify 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:** + +```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:** + +```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: + +```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: + +```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** + +```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** + +```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: + +```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: + +```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 +``` |