Segment Routing to Replace 6PE | IOS-XE Configuration

[steven.crutchley]

I'm trying to confirm SR to replace 6PE in a lab that I'm running. I've attached a couple of pictures to show how I understand the setup to work (and to show how bad my handwritting is and how much I love to color code )

Firstly this is how I understand 6PE to work (assuming 2001:CAFE:BABE::/64 is a subnet which PE2 is receiving from some CE that isn't shown):

Stock standard 6PE. So to migrate to SR, I deploy v6 across the core, enable v6 loopbacks with appropriate Node-SIDs, and establish native IPv6 Unicast BGP sessions to the reflectors. SR is enabled and preferred. The setup should work as follows:

 Im trying to set my lab up as you see above. But PE2 is IOS-XE and I cannot, for the life of me, find out how to give an IPv6 Loopback address a Node SID. IOS-XR is easy:

router isis LAB
 interface Loopback0
  passive
  address-family ipv4 unicast
   prefix-sid absolute 16401
  !
  address-family ipv6 unicast
   prefix-sid absolute 16001
  !

And I can see that SID advertised into IS-IS:

RP/0/RP0/CPU0:PE1#sh isis database verbose PE1.00-00
<snip>
  IPv6 Address:   2001:1ab::1
  Metric: 0          MT (IPv6 Unicast) IPv6 2001:1ab::1/128
    Prefix-SID Index: 1, Algorithm:0, R:0 N:1 P:0 E:0 V:0 L:0
    Prefix Attribute Flags: X:0 R:0 N:1
<snip>

But when I do the same thing on IOS-XE it seems I cant even configure a v6 node SID:

PE2#sh run | sec segment-routing
segment-routing mpls
 !
 set-attributes
  address-family ipv4
   sr-label-preferred
  exit-address-family
 !
 connected-prefix-sid-map
  address-family ipv4
   2.2.2.2/32 absolute 16402 range 1
  exit-address-family
 !
 segment-routing mpls
PE2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
PE2(config)#segment-routing mpls
PE2(config-srmpls)# connected-prefix-sid-map
PE2(config-srmpls-conn)#address-family ?
  ipv4  Address Family

PE2(config-srmpls-conn)#

Have I understood the concepts correctly and can someone advise what the correct syntax is? Every time I search for IPv6 Node SID I get hit with SRv6 papers, which is not what I'm after.

I can provider fuller configs if needed, but my actual lab is a bit different (hostnames, SID values etc) so it wont match exactly what is above, but the principle is the same. 

[steven.crutchley · Accepted solution]

So after speaking with Cisco, they've confirmed that IOS-XE does not support IPv6 SR MPLS - and there are no plans on the roadmap to do so at this time. 

However SRv6 (using a v6 header in the data plane rather than an MPLS label) will be supported on XE in the near future. We'll keep using 6PE until then.