i have flowsec session between exabgp and cisco ios-xr ,noticed on cisco ios-xr i am not seeing the nexthop.

[vijayqwe]

Here is the exabgp configuration: using version 4.2.25

neighbor 10.55.55.1 {
  router-id 10.55.55.2;
  local-address 10.55.55.2;
  local-as 15404;
  peer-as 15405;

  family {
    ipv4 flow;
  }

  flow {
    route flow-web-redirect {
      match {
        source 192.0.2.1/32;
        destination 198.51.100.1/32;
        protocol tcp;
        destination-port =80;
      }
      then {
		redirect-to-nexthop-ietf 10.54.5.248;
      }
    }
  }
}

[root@ns1 exabgp_redirect]# exabgpcli show adj-rib out 
neighbor 10.55.55.1 ipv4 flow flow destination-ipv4 198.51.100.1/32 source-ipv4 192.0.2.1/32 protocol =tcp destination-port =80

In the captured packet could see Type as 0x01 and subtype and subtype as 0x0c . I think type should be 0x08 and subtype 0x00 .

https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/711x/routing/configuration/guide/b-routing-cg-asr9000-711x/implementing-bgp-flowspec.html#task_657D4896618945E58A252420B491BFF8

Below the snip of the capture.

Carried extended communities: (2 communities)
    Unknown subtype 0x0c: 10.54.5.248:0 [Transitive IPv4-Address-Specific]
        Type: Transitive IPv4-Address-Specific (0x01)
            0... .... = IANA Authority: Allocated on First Come First Serve Basis
            .0.. .... = Transitive across ASes: Transitive
        Subtype (IPv4): Unknown (0x0c)
        IPv4 address: 10.54.5.248
        2-Octet AN: 0

Could you help on this.

[vijayqwe]

on ios-xr i dont see the nexthop been set.

sr1.BLB#sh bgp  ipv4  flowspec 
Wed Jul 23 12:39:20.852 UTC
BGP router identifier 10.91.126.101, local AS number 8220
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0   RD version: 91
BGP table nexthop route policy: 
BGP main routing table version 91
BGP NSR Initial initsync version 2 (Reached)
BGP NSR/ISSU Sync-Group versions 91/0
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*> Dest:198.51.100.1/32,Source:192.0.2.1/32,Proto:=6,DPort:=80/144
                    ###   0.0.0.0   >>> note here.                             0 15404 i 

Processed 1 prefixes, 1 paths

[vijayqwe]

Also tried this option:

neighbor 10.55.55.1 {
  router-id 10.55.55.2;
  local-address 10.55.55.2;
  local-as 15404;
  peer-as 8220;

  family {
    ipv4 flow;
  }

  flow {
    route flow-web-redirect {
	  next-hop 10.54.5.248;
      match {
        source 192.0.2.1/32;
        destination 198.51.100.1/32;
        protocol tcp;
        destination-port =80;
      }
      then {
		redirect-to-nexthop;
      }
    }
  }
}

Though exabgp is advertising the route , cisco ios-xr not process it.

ns1 exabgp_redirect]# exabgpcli show adj-rib out                             
neighbor 10.55.55.1 ipv4 flow flow destination-ipv4 198.51.100.1/32 source-ipv4 192.0.2.1/32 protocol =tcp destination-port =80 next-hop 10.54.5.248


:sr1.BLB#sh bgp  ipv4  flowspec 
Wed Jul 23 13:03:36.855 UTC
RP/0/RSP0/CPU0:sr1.BLB#

In the packet capture it is showing as "[Expert Info (Error/Malformed): The length (4) of Next Hop (FlowSpec) is not zero]"

        Path Attribute - EXTENDED_COMMUNITIES
            Flags: 0xc0, Optional, Transitive, Complete
                1... .... = Optional: Set
                .1.. .... = Transitive: Set
                ..0. .... = Partial: Not set
                ...0 .... = Extended-Length: Not set
                .... 0000 = Unused: 0x0
            Type Code: EXTENDED_COMMUNITIES (16)
            Length: 8
            Carried extended communities: (1 community)
                Unknown type 0x08 subtype 0x00: 0x0000 0x0000 0x0000 [Transitive Flow spec redirect/mirror to IP next-hop]
                    Type: Transitive Flow spec redirect/mirror to IP next-hop (0x08)
                        0... .... = IANA Authority: Allocated on First Come First Serve Basis
                        .0.. .... = Transitive across ASes: Transitive
                    Subtype: 0x00
                    Raw Value: 0x0000 0x0000 0x0000
        Path Attribute - MP_REACH_NLRI
            Flags: 0x80, Optional, Non-transitive, Complete
                1... .... = Optional: Set
                .0.. .... = Transitive: Not set
                ..0. .... = Partial: Not set
                ...0 .... = Extended-Length: Not set
                .... 0000 = Unused: 0x0
            Type Code: MP_REACH_NLRI (14)
            Length: 28
            Address family identifier (AFI): IPv4 (1)
            Subsequent address family identifier (SAFI): Flow Spec Filter (133)
            Next hop: 0a3605f8
                [Expert Info (Error/Malformed): The length (4) of Next Hop (FlowSpec) is not zero]
                    [The length (4) of Next Hop (FlowSpec) is not zero]
                    [Severity level: Error]
                    [Group: Malformed]
                [Expert Info (Error/Malformed): Unknown Next Hop length (4 bytes)]
                    [Unknown Next Hop length (4 bytes)]
                    [Severity level: Error]
                    [Group: Malformed]

[vijayqwe]

Any update on this.