[FROG] fd80 prefix allocation

[Tran (US), Katherine K]

In frr.conf, bgp neighbors are set to fd80::X:X. But, the next hop is shown to be fe80::X:X when the command "show bgp" is issued. Please see below for more details. 

Note: Some MTUs are set to 1400. The original configuration was run in Quagga and worked. 

--------------------------------------------------------------------------------------------
FRR vtysh terminal
--------------------------------------------------------------------------------------------
AERO-Relay# show bgp
BGP table version is 10896, local router ID is 10.0.4.2, vrf id 0 Default local pref 100, local AS 1 Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self Origin codes:  i - IGP, e - EGP, ? - incomplete

   Network                           Next Hop            Metric LocPrf      Weight Path
*> 2001:db8:1:1::/64       fe80::1:2             1024                        0 2 ?
*> 2001:db8:1:2::/64       fe80::2:2             1024                        0 3 ?
*> 2001:db8:1:3::/64       fe80::1:2             1024                        0 2 ?
*> 2001:db8:1:4::/64       fe80::2:2             1024                        0 3 ?
*> fd80::1:0/112               fe80::1:2                0                            0 2 ?
*> fd80::1:2/128               fe80::1:2             1024                        0 2 ?
*> fd80::2:0/112               fe80::2:2                0                             0 3 ?
*> fd80::2:2/128               fe80::2:2             1024                        0 3 ?

Displayed  8 routes and 8 total paths

--------------------------------------------------------------------------------------------
frr.conf
--------------------------------------------------------------------------------------------
log file /var/log/frr/frr.log debugging

interface eth0
  ip address 10.0.4.2/24
  
interface eth1
  ipv6 address 2001::1/64

interface aero2
  ipv6 address fd80::1:1/112
  
interface aero3
  ipv6 address fd80::2:1/112
  

! Static routes
ip route 0.0.0.0/0 10.0.4.1


! BGP configuration
!
! You should configure the AS number below, ! along with this router's peers.
!
router bgp 1
  bgp router-id 10.0.4.2
  no bgp default ipv4-unicast
  neighbor fd80::1:2 remote-as 2
  neighbor fd80::1:2 interface aero2
  neighbor fd80::2:2 remote-as 3
  neighbor fd80::2:2 interface aero3
  address-family ipv6
  neighbor fd80::1:2 activate
  neighbor fd80::1:2 next-hop-self
  neighbor fd80::1:2 default-originate
  neighbor fd80::1:2 distribute-list blackhole out
  neighbor fd80::2:2 activate
  neighbor fd80::2:2 next-hop-self
  neighbor fd80::2:2 default-originate
  neighbor fd80::2:2 distribute-list blackhole out
  exit-address-family
  ipv6 access-list blackhole deny any

Thank you, 
Katherine

-----Original Message-----
From: Chriztoffer Hansen [mailto:ch at ntrv.dk] 
Sent: Tuesday, April 14, 2020 3:26 PM
To: Tran (US), Katherine K <katherine.k.tran at boeing.com>
Cc: frog at lists.frrouting.org
Subject: Re: [FROG] fd80 prefix allocation

Katherine,

On Tue, 14 Apr 2020 at 19:43, Tran (US), Katherine K <katherine.k.tran at boeing.com> wrote:
> Does anyone know how FRR treats “fd80” prefixes?
> My configuration uses “fd80” prefixes as Unique Local IPv6 Unicast Addresses (IETF RFC 4193), which can be routed. But, somehow, FRR changes these “fd80” addresses to “fe80”.

A (sanitized?) configuration snippet/example from your set-up will help you get relevant answers ;)

Cheers,
Chriztoffer