====== SRv6 Global VRF (RFC 9252) with FRRouting & Containerlab ======

===== Introduction & Summary =====
This document outlines the deployment of a pure **Segment Routing over IPv6 (SRv6)** fabric using FRRouting (FRR 10.6+) and Linux. 

Unlike traditional deployments that rely on L3VPNs (VRFs) to carry customer traffic, this architecture implements **RFC 9252 (BGP Based L3 Service over SRv6)** directly in the **Global Routing Table (Default VRF)**. It supports both Global IPv4 and Global IPv6 over an SRv6 core.

**Key Achievements of this Lab:**
  * No VRFs required on the PE routers.
  * BGP dynamically allocates SRv6 SIDs (End.DT4 and End.DT6) for global connected/redistributed routes.
  * IS-IS is used as the IPv6 underlay.
  * Custom MTU handling to accommodate SRv6 encapsulation overhead without impacting standard 1500-byte client MTUs.

===== Key Findings & Important Workarounds =====
Implementing Global SRv6 (RFC 9252) natively in Linux/FRR without VRFs exposes a conflict between FRRouting's dynamic SID allocation and the Linux kernel's security model. Below are the critical "gotchas" discovered:

==== 1. The Kernel Decapsulation Conflict (End.DT4 vs Table 254) ====
When doing global IPv4 over SRv6, BGP assigns the ''End.DT4'' behavior to the IPv4 prefix. However, the Linux Kernel's ''seg6local'' engine strictly expects ''End.DT4'' (IPv4 decapsulation) to point to an explicit VRF table. When FRR attempts to install this instruction into the global routing table (''table 254''), the kernel throws an ''EINVAL'' error, and FRR marks the SRv6 instruction as Rejected (''B>r'').
  * **The Fix:** Bypass the kernel's SRv6 engine entirely using native Linux local routing.
  * By routing the entire SRv6 Locator block to the ''local'' routing table, the native Linux IPv6 stack will intercept the packets. It sees the Next Header is IPv4 (4), automatically strips the outer IPv6 SRv6 header, and routes the inner IPv4 payload natively, completely bypassing the ''End.DT4'' kernel restriction.
  * Add this to the startup script of every PE router:
<code bash>
ip -6 route add local 2001:db8:b::/48 dev lo
</code>

==== 2. BGP Encapsulation Relax ====
Standard BGP ''ipv4 unicast'' and ''ipv6 unicast'' address families silently drop SRv6 Prefix-SID attributes (Attribute 40) because they are typically reserved for L3VPNs. 
  * **The Fix:** Explicitly tell BGP to attach and accept SRv6 SIDs on global routes using the ''relax'' keyword on PEs and Route Reflectors:
<code text>
neighbor RR encapsulation-srv6-relax
</code>

==== 3. MTU and SRv6 Overhead ====
SRv6 adds exactly **64 bytes of overhead** (40 bytes for the outer IPv6 header + 24 bytes for the Segment Routing Header containing 1 SID).
  * **The Fix:** To allow clients to send standard 1500-byte payloads without fragmentation, the core links (between P and PE routers) must have their MTU increased to at least **1564 bytes**.


----

===== Containerlab Topology =====
<code yaml>
name: srv6-1060

mgmt:
  network: clab-mgmt-net
  ipv4-subnet: 172.99.20.0/24
  ipv6-subnet: ""

topology:
  nodes:
    rr1:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - rr1/daemons:/etc/frr/daemons
        - rr1/frr.conf:/etc/frr/frr.conf
        - rr1/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1

    rr2:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - rr2/daemons:/etc/frr/daemons
        - rr2/frr.conf:/etc/frr/frr.conf
        - rr2/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1

    p1:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - p1/daemons:/etc/frr/daemons
        - p1/frr.conf:/etc/frr/frr.conf
        - p1/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth3.seg6_enabled=1

    p2:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - p2/daemons:/etc/frr/daemons
        - p2/frr.conf:/etc/frr/frr.conf
        - p2/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth3.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth4.seg6_enabled=1

    p3:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - p3/daemons:/etc/frr/daemons
        - p3/frr.conf:/etc/frr/frr.conf
        - p3/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth3.seg6_enabled=1

    p4:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - p4/daemons:/etc/frr/daemons
        - p4/frr.conf:/etc/frr/frr.conf
        - p4/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth3.seg6_enabled=1

    p5:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - p5/daemons:/etc/frr/daemons
        - p5/frr.conf:/etc/frr/frr.conf
        - p5/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth3.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth4.seg6_enabled=1

    p6:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - p6/daemons:/etc/frr/daemons
        - p6/frr.conf:/etc/frr/frr.conf
        - p6/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth3.seg6_enabled=1
        
    pe1:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - pe1/daemons:/etc/frr/daemons
        - pe1/frr.conf:/etc/frr/frr.conf
        - pe1/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - sleep 4
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv4.conf.sr0.forwarding=1
        - sysctl -w net.ipv6.conf.sr0.forwarding=1
        - sysctl -w net.ipv6.conf.sr0.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - ip -6 route add local 2001:db8:b::/48 dev lo

    pe4:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - pe4/daemons:/etc/frr/daemons
        - pe4/frr.conf:/etc/frr/frr.conf
        - pe4/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - sleep 4
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv4.conf.sr0.forwarding=1
        - sysctl -w net.ipv6.conf.sr0.forwarding=1
        - sysctl -w net.ipv6.conf.sr0.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - ip -6 route add local 2001:db8:e::/48 dev lo

    pe3:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - pe3/daemons:/etc/frr/daemons
        - pe3/frr.conf:/etc/frr/frr.conf
        - pe3/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - sleep 4
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv4.conf.sr0.forwarding=1
        - sysctl -w net.ipv6.conf.sr0.forwarding=1
        - sysctl -w net.ipv6.conf.sr0.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - ip -6 route add local 2001:db8:d::/48 dev lo

    pe6:
      kind: linux
      image: quay.io/frrouting/frr:10.6.1
      cmd: bash -c "ip link add sr0 type dummy; ip link set sr0 up; /usr/lib/frr/frrinit.sh start && tail -f /dev/null"
      sysctls:
        net.ipv4.ip_forward: 1
        net.ipv4.conf.all.forwarding: 1
        net.ipv6.conf.all.forwarding: 1
        net.ipv6.conf.default.forwarding: 1
        net.ipv6.seg6_flowlabel: 1
        net.ipv6.conf.default.seg6_enabled: 1
        net.ipv6.conf.all.seg6_enabled: 1
        net.vrf.strict_mode: 0
        net.ipv6.conf.all.accept_source_route: 1
      binds:
        - pe6/daemons:/etc/frr/daemons
        - pe6/frr.conf:/etc/frr/frr.conf
        - pe6/vtysh.conf:/etc/frr/vtysh.conf
      exec:
        - sleep 4
        - ip link add dummy0 type dummy
        - ip link set dummy0 up
        - ip link add sr0 type dummy
        - ip link set sr0 up
        - sysctl -w net.ipv4.conf.sr0.forwarding=1
        - sysctl -w net.ipv6.conf.sr0.forwarding=1
        - sysctl -w net.ipv6.conf.sr0.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth1.seg6_enabled=1
        - sysctl -w net.ipv6.conf.eth2.seg6_enabled=1
        - ip -6 route add local 2001:db8:10::/48 dev lo

    clienta1-1:
      kind: linux
      image: alpine:latest
      exec:
        - apk add iputils-ping
        - ip -4 addr add 192.168.131.2/24 dev eth1
        - ip link set dev eth1 up
        - ip -4 route del default
        - ip -4 route add 0.0.0.0/0 via 192.168.131.1
        - ip -6 address add fdd8:8b9e:07c5::2/64 dev eth1
        - ip -6 route add ::/0 via fdd8:8b9e:07c5::1
         
    clienta1-3:
      kind: linux
      image: alpine:latest
      exec:
        - apk add iputils-ping
        - ip -4 addr add 192.168.133.2/24 dev eth1
        - ip link set dev eth1 up
        - ip -4 route del default
        - ip -4 route add 0.0.0.0/0 via 192.168.133.1
        - ip -6 address add fdf2:f16f:a002::2/64 dev eth1
        - ip -6 route add ::/0 via fdf2:f16f:a002::1

    clienta1-4:
      kind: linux
      image: alpine:latest
      exec:
        - apk add iputils-ping
        - ip -4 addr add 192.168.134.2/24 dev eth1
        - ip link set dev eth1 up
        - ip -4 route del default
        - ip -4 route add 0.0.0.0/0 via 192.168.134.1
        - ip -6 address add fde4:1b4c:2ef0::2/64 dev eth1
        - ip -6 route add ::/0 via fde4:1b4c:2ef0::1

    clienta1-6:
      kind: linux
      image: alpine:latest
      exec:
        - apk add iputils-ping
        - ip -4 addr add 192.168.136.2/24 dev eth1
        - ip link set dev eth1 up
        - ip -4 route del default
        - ip -4 route add 0.0.0.0/0 via 192.168.136.1
        - ip -6 address add fdcb:a001:3440::2/64 dev eth1
        - ip -6 route add ::/0 via fdcb:a001:3440::1

  links:
    - endpoints: ["p1:eth1", "p2:eth1"]
      mtu: 1564
    - endpoints: ["p1:eth2", "p4:eth2"]
      mtu: 1564
    - endpoints: ["p2:eth2", "p3:eth2"]
      mtu: 1564
    - endpoints: ["p2:eth3", "p5:eth3"]
      mtu: 1564
    - endpoints: ["p3:eth1", "p6:eth1"]
      mtu: 1564
    - endpoints: ["p6:eth2", "p5:eth2"]
      mtu: 1564
    - endpoints: ["p5:eth1", "p4:eth1"]
      mtu: 1564
    - endpoints: ["p1:eth3", "pe1:eth1"]
      mtu: 1564
    - endpoints: ["p4:eth3", "pe4:eth1"]
      mtu: 1564
    - endpoints: ["p3:eth3", "pe3:eth1"]
      mtu: 1564
    - endpoints: ["p6:eth3", "pe6:eth1"]
      mtu: 1564
    - endpoints: ["p2:eth4", "rr1:eth1"]
      mtu: 1564
    - endpoints: ["p5:eth4", "rr2:eth1"]
      mtu: 1564
    - endpoints: ["pe1:eth2", "clienta1-1:eth1"]
      mtu: 1500
    - endpoints: ["pe3:eth2", "clienta1-3:eth1"]
      mtu: 1500
    - endpoints: ["pe4:eth2", "clienta1-4:eth1"]
      mtu: 1500
    - endpoints: ["pe6:eth2", "clienta1-6:eth1"]
      mtu: 1500
</code>

===== PE Configurations =====

==== PE1 ====
<code - pe1 config>
frr version 10.6.1_git
frr defaults traditional
hostname pe1
!
ip prefix-list LAN_IPV4 seq 10 permit 192.168.131.0/24
!
ipv6 prefix-list LAN_IPV6 seq 10 permit fdd8:8b9e:7c5::/64
!
route-map GLOBAL_IPV4-OUT permit 10
 match ip address prefix-list LAN_IPV4
exit
!
route-map GLOBAL_IPV4-OUT deny 999
exit
!
route-map GLOBAL_IPV6-OUT permit 10
 match ipv6 address prefix-list LAN_IPV6
exit
!
route-map GLOBAL_IPV6-OUT deny 999
exit
!
ip router-id 172.16.0.11
!
interface eth1
 description "to p1 - eth3"
 ipv6 address 2001:db8:1a::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to clienta-1 - eth1"
 ip address 192.168.131.1/24
 ipv6 address fdd8:8b9e:7c5::1/64
exit
!
interface lo
 ipv6 address 2001:db8:b::1/128
 ipv6 router isis SR
 isis passive
exit
!
router bgp 65577
 neighbor RR peer-group
 neighbor RR remote-as 65577
 neighbor RR password cisco123
 neighbor RR update-source 2001:db8:b::1
 neighbor RR capability extended-nexthop
 neighbor 2001:db8:101::1 peer-group RR
 neighbor 2001:db8:102::1 peer-group RR
 !
 segment-routing srv6
  locator locator0
 exit
 !
 address-family ipv4 unicast
  redistribute connected route-map GLOBAL_IPV4-OUT
  neighbor RR encapsulation-srv6-relax
  sid export auto
 exit-address-family
 !
 address-family ipv6 unicast
  redistribute connected route-map GLOBAL_IPV6-OUT
  neighbor RR activate
  neighbor RR encapsulation-srv6-relax
  sid export auto
 exit-address-family
exit
!
router isis SR
 net 49.0000.0000.0000.0011.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  locators
   locator locator0
    prefix 2001:db8:b::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>


==== PE3 ====
<code - pe3 config>
frr version 10.6.1_git
frr defaults traditional
hostname pe3
!
ip prefix-list LAN_IPV4 seq 10 permit 192.168.133.0/24
!
ipv6 prefix-list LAN_IPV6 seq 10 permit fdf2:f16f:a002::/64
!
route-map GLOBAL_IPV4-OUT permit 10
 match ip address prefix-list LAN_IPV4
exit
!
route-map GLOBAL_IPV4-OUT deny 999
exit
!
route-map GLOBAL_IPV6-OUT permit 10
 match ipv6 address prefix-list LAN_IPV6
exit
!
route-map GLOBAL_IPV6-OUT deny 999
exit
!
ip router-id 172.16.0.13
!
interface eth1
 description "to p3 - eth3"
 ipv6 address 2001:db8:3a::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to clienta-3 - eth1"
 ip address 192.168.133.1/24
 ipv6 address fdf2:f16f:a002::1/64
exit
!
interface lo
 ipv6 address 2001:db8:d::1/128
 ipv6 router isis SR
 isis passive
exit
!
router bgp 65577
 neighbor RR peer-group
 neighbor RR remote-as 65577
 neighbor RR password cisco123
 neighbor RR update-source 2001:db8:d::1
 neighbor RR capability extended-nexthop
 neighbor 2001:db8:101::1 peer-group RR
 neighbor 2001:db8:102::1 peer-group RR
 !
 segment-routing srv6
  locator locator0
 exit
 !
 address-family ipv4 unicast
  redistribute connected route-map GLOBAL_IPV4-OUT
  neighbor RR encapsulation-srv6-relax
  sid export auto
 exit-address-family
 !
 address-family ipv6 unicast
  redistribute connected route-map GLOBAL_IPV6-OUT
  neighbor RR activate
  neighbor RR encapsulation-srv6-relax
  sid export auto
 exit-address-family
exit
!
router isis SR
 net 49.0000.0000.0000.0013.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  locators
   locator locator0
    prefix 2001:db8:d::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>


==== PE4 ====
<code - pe4 config>
frr version 10.6.1_git
frr defaults traditional
hostname pe4
!
ip prefix-list LAN_IPV4 seq 10 permit 192.168.134.0/24
!
ipv6 prefix-list LAN_IPV6 seq 10 permit fde4:1b4c:2ef0::/64
!
route-map GLOBAL_IPV4-OUT permit 10
 match ip address prefix-list LAN_IPV4
exit
!
route-map GLOBAL_IPV4-OUT deny 999
exit
!
route-map GLOBAL_IPV6-OUT permit 10
 match ipv6 address prefix-list LAN_IPV6
exit
!
route-map GLOBAL_IPV6-OUT deny 999
exit
!
ip router-id 172.16.0.14
!
interface eth1
 description "to p4 - eth3"
 ipv6 address 2001:db8:4a::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to clienta-4 - eth1"
 ip address 192.168.134.1/24
 ipv6 address fde4:1b4c:2ef0::1/64
exit
!
interface lo
 ipv6 address 2001:db8:e::1/128
 ipv6 router isis SR
 isis passive
exit
!
router bgp 65577
 neighbor RR peer-group
 neighbor RR remote-as 65577
 neighbor RR password cisco123
 neighbor RR update-source 2001:db8:e::1
 neighbor RR capability extended-nexthop
 neighbor 2001:db8:101::1 peer-group RR
 neighbor 2001:db8:102::1 peer-group RR
 !
 segment-routing srv6
  locator locator0
 exit
 !
 address-family ipv4 unicast
  redistribute connected route-map GLOBAL_IPV4-OUT
  neighbor RR encapsulation-srv6-relax
  sid export auto
 exit-address-family
 !
 address-family ipv6 unicast
  redistribute connected route-map GLOBAL_IPV6-OUT
  neighbor RR activate
  neighbor RR encapsulation-srv6-relax
  sid export auto
 exit-address-family
exit
!
router isis SR
 net 49.0000.0000.0000.0014.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  locators
   locator locator0
    prefix 2001:db8:e::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>


==== PE6 ====
<code - pe6 config>
frr version 10.6.1_git
frr defaults traditional
hostname pe6
!
ip prefix-list LAN_IPV4 seq 10 permit 192.168.136.0/24
!
ipv6 prefix-list LAN_IPV6 seq 10 permit fdcb:a001:3440::/64
!
route-map GLOBAL_IPV4-OUT permit 10
 match ip address prefix-list LAN_IPV4
exit
!
route-map GLOBAL_IPV4-OUT deny 999
exit
!
route-map GLOBAL_IPV6-OUT permit 10
 match ipv6 address prefix-list LAN_IPV6
exit
!
route-map GLOBAL_IPV6-OUT deny 999
exit
!
ip router-id 172.16.0.16
!
interface eth1
 description "to p6 - eth3"
 ipv6 address 2001:db8:6a::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to clienta-6 - eth1"
 ip address 192.168.136.1/24
 ipv6 address fdcb:a001:3440::1/64
exit
!
interface lo
 ipv6 address 2001:db8:10::1/128
 ipv6 router isis SR
 isis passive
exit
!
router bgp 65577
 neighbor RR peer-group
 neighbor RR remote-as 65577
 neighbor RR password cisco123
 neighbor RR update-source 2001:db8:10::1
 neighbor RR capability extended-nexthop
 neighbor 2001:db8:101::1 peer-group RR
 neighbor 2001:db8:102::1 peer-group RR
 !
 segment-routing srv6
  locator locator0
 exit
 !
 address-family ipv4 unicast
  redistribute connected route-map GLOBAL_IPV4-OUT
  neighbor RR encapsulation-srv6-relax
  sid export auto
 exit-address-family
 !
 address-family ipv6 unicast
  redistribute connected route-map GLOBAL_IPV6-OUT
  neighbor RR activate
  neighbor RR encapsulation-srv6-relax
  sid export auto
 exit-address-family
exit
!
router isis SR
 net 49.0000.0000.0000.0016.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  locators
   locator locator0
    prefix 2001:db8:10::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>

===== P configurations =====

==== P1 ====
<code - p1 config>
frr version 10.5.1_git
frr defaults traditional
hostname p1
!
ip router-id 172.16.0.1
!
interface eth1
 description "to p2 - eth1"
 ipv6 address 2001:db8:12::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to p4 - eth2"
 ipv6 address 2001:db8:14::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth3
 description "to pe1 - eth3"
 ipv6 address 2001:db8:1a::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth4
 description "to gw1 - eth1"
 ipv6 address 2001:db8:f11::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface lo
 ipv6 address 2001:db8:1::1/128
 ipv6 router isis SR
 isis passive
exit
!
router isis SR
 net 49.0000.0000.0000.0001.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  static-sids
   sid 2001:db8:1::1/128 locator locator0 behavior uN
  exit
  !
 exit
 !
 srv6
  locators
   locator locator0
    prefix 2001:db8:1::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>

==== P2 ====
<code - p2 config>
frr version 10.5.1_git
frr defaults traditional
hostname p2
!
ip router-id 172.16.0.2
!
interface eth1
 description "to p1 - eth1"
 ipv6 address 2001:db8:12::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to p3 - eth2"
 ipv6 address 2001:db8:23::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth3
 description "to p5 - eth3"
 ipv6 address 2001:db8:25::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth4
 description "to rr1 - eth1"
 ipv6 address 2001:db8:2101::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface lo
 ipv6 address 2001:db8:2::1/128
 ipv6 router isis SR
 isis passive
exit
!
router isis SR
 net 49.0000.0000.0000.0002.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  static-sids
   sid 2001:db8:2::1/128 locator locator0 behavior uN
  exit
  !
 exit
 !
 srv6
  locators
   locator locator0
    prefix 2001:db8:2::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>

==== P3 ====
<code - p3 config>
frr version 10.5.1_git
frr defaults traditional
hostname p3
!
ip router-id 172.16.0.3
!
interface eth1
 description "to p6 - eth1"
 ipv6 address 2001:db8:36::3/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to p2 - eth2"
 ipv6 address 2001:db8:23::3/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth3
 description "to pe3 - eth1"
 ipv6 address 2001:db8:3a::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface lo
 ipv6 address 2001:db8:3::1/128
 ipv6 router isis SR
 isis passive
exit
!
router isis SR
 net 49.0000.0000.0000.0003.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  static-sids
   sid 2001:db8:3::1/128 locator locator0 behavior uN
  exit
  !
 exit
 !
 srv6
  locators
   locator locator0
    prefix 2001:db8:3::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>

==== P4 ====
<code - p4 config>
frr version 10.5.1_git
frr defaults traditional
hostname p4
!
ip router-id 172.16.0.4
!
interface eth1
 description "to p5 - eth1"
 ipv6 address 2001:db8:45::4/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to p1 - eth2"
 ipv6 address 2001:db8:12::4/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth3
 description "to pe4 - eth1"
 ipv6 address 2001:db8:4a::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface lo
 ipv6 address 2001:db8:4::1/128
 ipv6 router isis SR
 isis passive
exit
!
router isis SR
 net 49.0000.0000.0000.0004.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  static-sids
   sid 2001:db8:4::1/128 locator locator0 behavior uN
  exit
  !
 exit
 !
 srv6
  locators
   locator locator0
    prefix 2001:db8:4::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>

==== P5 ====
<code - p5 config>
frr version 10.5.1_git
frr defaults traditional
hostname p5
!
ip router-id 172.16.0.5
!
interface eth1
 description "to p4 - eth1"
 ipv6 address 2001:db8:45::5/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to p6 - eth2"
 ipv6 address 2001:db8:56::5/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth3
 description "to p2 - eth3"
 ipv6 address 2001:db8:25::5/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth4
 description "to rr2 - eth1"
 ipv6 address 2001:db8:5102::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface lo
 ipv6 address 2001:db8:5::1/128
 ipv6 router isis SR
 isis passive
exit
!
router isis SR
 net 49.0000.0000.0000.0005.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  static-sids
   sid 2001:db8:5::1/128 locator locator0 behavior uN
  exit
  !
 exit
 !
 srv6
  locators
   locator locator0
    prefix 2001:db8:5::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>

==== P6 ====
<code - p6 config>
frr version 10.5.1_git
frr defaults traditional
hostname p6
!
ip router-id 172.16.0.6
!
interface eth1
 description "to p3 - eth1"
 ipv6 address 2001:db8:36::6/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth2
 description "to p5 - eth2"
 ipv6 address 2001:db8:56::6/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth3
 description "to pe6 - eth1"
 ipv6 address 2001:db8:6a::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface eth4
 description "to gw2 - eth1"
 ipv6 address 2001:db8:f62::1/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface lo
 ipv6 address 2001:db8:6::1/128
 ipv6 router isis SR
 isis passive
exit
!
router isis SR
 net 49.0000.0000.0000.0006.00
 segment-routing srv6
  locator locator0
 exit
exit
!
segment-routing
 srv6
  static-sids
   sid 2001:db8:6::1/128 locator locator0 behavior uN
  exit
  !
 exit
 !
 srv6
  locators
   locator locator0
    prefix 2001:db8:6::/48
   exit
   !
  exit
  !
 exit
 !
exit
!
</code>


===== Route Reflectors configuration =====

==== RR1 ====
<code - rr1 config>
frr version 10.6.1_git
frr defaults traditional
hostname rr1
!
interface eth1
 description "to p2 - eth4"
 ipv6 address 2001:db8:2101::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface lo
 ipv6 address 2001:db8:101::1/128
 ipv6 router isis SR
 isis passive
exit
!
router bgp 65577
 bgp route-reflector allow-outbound-policy
 neighbor PE peer-group
 neighbor PE remote-as 65577
 neighbor PE password cisco123
 neighbor PE update-source 2001:db8:101::1
 neighbor PE capability extended-nexthop
 neighbor 2001:db8:b::1 peer-group PE
 neighbor 2001:db8:b::1 description "PE1"
 neighbor 2001:db8:d::1 peer-group PE
 neighbor 2001:db8:d::1 description "PE3"
 neighbor 2001:db8:e::1 peer-group PE
 neighbor 2001:db8:e::1 description "PE4"
 neighbor 2001:db8:10::1 peer-group PE
 neighbor 2001:db8:10::1 description "PE6"
 neighbor 2001:db8:11::1 peer-group PE
 neighbor 2001:db8:11::1 description "GW1"
 neighbor 2001:db8:12::1 peer-group PE
 neighbor 2001:db8:12::1 description "GW2"
 !
 address-family ipv4 unicast
  neighbor PE route-reflector-client
  neighbor PE encapsulation-srv6-relax
 exit-address-family
 !
 address-family ipv6 unicast
  neighbor PE activate
  neighbor PE route-reflector-client
  neighbor PE encapsulation-srv6-relax
 exit-address-family
exit
!
router isis SR
 net 49.0000.0000.0000.0101.00
 segment-routing srv6
  locator locator0
 exit
exit
!
</code>

==== RR2 ====
<code - rr2 config>
frr version 10.6.1_git
frr defaults traditional
hostname rr2
!
ip router-id 172.16.0.102
!
interface eth1
 description "to p5 - eth4"
 ipv6 address 2001:db8:5102::2/64
 ipv6 router isis SR
 isis network point-to-point
exit
!
interface lo
 ipv6 address 2001:db8:102::1/128
 ipv6 router isis SR
 isis passive
exit
!
router bgp 65577
 bgp route-reflector allow-outbound-policy
 neighbor PE peer-group
 neighbor PE remote-as 65577
 neighbor PE password cisco123
 neighbor PE update-source 2001:db8:102::1
 neighbor PE capability extended-nexthop
 neighbor 2001:db8:b::1 peer-group PE
 neighbor 2001:db8:b::1 description "PE1"
 neighbor 2001:db8:d::1 peer-group PE
 neighbor 2001:db8:d::1 description "PE3"
 neighbor 2001:db8:e::1 peer-group PE
 neighbor 2001:db8:e::1 description "PE4"
 neighbor 2001:db8:10::1 peer-group PE
 neighbor 2001:db8:10::1 description "PE6"
 neighbor 2001:db8:11::1 peer-group PE
 neighbor 2001:db8:11::1 description "GW1"
 neighbor 2001:db8:12::1 peer-group PE
 neighbor 2001:db8:12::1 description "GW2"
 !
 address-family ipv4 unicast
  neighbor PE route-reflector-client
  neighbor PE encapsulation-srv6-relax
 exit-address-family
 !
 address-family ipv6 unicast
  neighbor PE activate
  neighbor PE route-reflector-client
  neighbor PE encapsulation-srv6-relax
 exit-address-family
exit
!
router isis SR
 net 49.0000.0000.0000.0102.00
 segment-routing srv6
  locator locator0
 exit
exit
!
</code>