# SRv6 uSID w/ EVPN-VPWS and BGP IPv4/IPv6 Load **top1.vpnv4v6.srv6.configured.cfg** ``` #IOS-XR configure load top1.vpnv4v6.srv6.usid.services.init.cfg commit replace y #IOS-XE config replace flash:top1.vpnv4v6.srv6.usid.services.init.cfg ``` SRv6 uSID is already preconfigured in the core. Configure an EVPN-VPWS service between CSR1 and CSR3 using SRv6 as the underlay. * CSR1 is configured for 10.0.0.1/24 on Gi2.3311 * CSR3 is configured for 10.0.0.3/24 on Gi2.3333 * This will not work in the data plane on XRd Configure BGP IPv4/IPv6 in the global table between CSR2 and CSR4 also using SRv6 as the underlay. * The BGP peerings are already setup in the global table ## Answer ``` #XR5 evpn segment-routing srv6 locator CCIE ! l2vpn xconnect group VPWS p2p CUSTOMER interface GigabitEthernet0/0/0/0.3311 neighbor evpn evi 100 service 100 segment-routing srv6 #XR7 evpn segment-routing srv6 locator CCIE ! l2vpn xconnect group VPWS p2p CUSTOMER interface GigabitEthernet0/0/0/0.3333 neighbor evpn evi 100 service 100 segment-routing srv6 #XR6, XR8 router bgp 100 segment-routing srv6 locator CCIE ! address-family ipv4 unicast segment-routing srv6 alloc mode per-vrf ! address-family ipv6 unicast segment-routing srv6 alloc mode per-vrf ! neighbor-group RR address-family ipv4 unicast next-hop-self encapsulation-type srv6 ! address-family ipv6 unicast next-hop-self encapsulation-type srv6 ``` ## Explanation SRv6 can be used as the data plane for EVPN-VPWS and global IPv4/IPv6 unicast. It does not appear to be supported for bridged EVPN. But bridge-domains are not configurable on XRv9K anyways. For EVPN-VPWS, we must do two things. First, we configure the locator that EVPN will use: ``` evpn segment-routing srv6 locator CCIE ``` Next, we configure the encapsulation as SRv6 on the xconnect: ``` l2vpn xconnect group VPWS p2p CUSTOMER neighbor evpn evi 100 service 100 segment-routing srv6 ``` Alternatively, we can specify the locator on the individual p2p xconnect. However, we still must activate SRv6 under EVPN: ``` evpn segment-routing srv6 ! l2vpn xconnect group VPWS p2p CUSTOMER neighbor evpn evi 100 service 100 segment-routing srv6 locator CCIE ``` The SID advertisement works the same as we have seen with L3VPN. The SID is advertised within a Prefix SID Sub TLV. The label field contains the function bits.

The PE installs this ::/64 SID into the FIB with a uDX2 instruction, which means to decapsulate and cross-connect for a layer 2 service.

Note that on XRv9K, this L2 service works in the data plane. However, on XRd, it seems that the node cannot do vlan rewrite operations, so this is not working in the data plane. Next, we configure BGP IPv4/IPv6 unicast in the global VRF for SRv6. This is just like 6PE, in which global IPv6 unicast is tunneled across an MPLS core by advertising a service label with the ipv6/unicast prefix. To configure this, we first need to fix an issue. The PEs are not setting next-hop-self on the routes. This causes the RRs to not select these prefixes as best because the nexthop is inaccessible. When these were VRF routes, the PE automatically sets next-hop-self for the VPNv4/v6 route, as the PE is technically the router originating the VPN route.

We fix this by setting next-hop-self: ``` #XR6, XR8 router bgp 100 neighbor-group RR address-family ipv4 unicast next-hop-self ! address-family ipv6 unicast next-hop-self ``` Next, we enable SRv6 for BGP the same as we did for L3VPN. We can also configure the locator to be used by default: ``` #XR6, XR8 router bgp 100 segment-routing srv6 locator CCIE ``` We must do two other things. We must set the SRv6 alloc mode under the global AFIs, and we must set the encapsulation type as SRv6 under the iBGP neighbor statements. ``` #XR6, XR8 router bgp 100 address-family ipv4 unicast segment-routing srv6 alloc mode per-vrf ! address-family ipv6 unicast segment-routing srv6 alloc mode per-vrf ! neighbor-group RR address-family ipv4 unicast encapsulation-type srv6 ! address-family ipv6 unicast encapsulation-type srv6 ``` Now the global prefixes have a SID associated with them. The difference with global IPv4/IPv6 unicast is that BGP-LU is not used, so there is no label field to place the function bits inside. This is just an optimization to better pack BGP updates, so it is not a major drawback.

Traffic between the two pairs of CEs should now be working:

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