[dev] Problems regarding BGP code 2, sub-code 7 when peering with Cisco IOS-XR Version 4.2.3 over IPv6

Christoffer Hansen netravnen at gmail.com
Tue Sep 26 12:06:16 EDT 2017 

FRRouting-Dev <dev at lists.frrouting.org>


Hit an interesting issue today. (for reference a lot of technical
details below)

I found myself unable to locate the option of turning BGP code 2,
sub-code 7 off when sending capabilities to a neighbor. (Spent some time
googling around but mostly found Cisco IOS-XR related stuff)

It appears Cisco IOS-XR does not yet support the use off
'additional-paths' (BGP code 2, sub-code 7) when exchanging neighbor
capabilities. But ONLY for IPv6 (IPv4 is supported).

So my question to the list (if anyone finds the time to answer) is: Does
FFRouting contain an option to turn off the multi-path feature /
specific sub-code when announcing BGPv4 capabilities to it's neighbor(s)
over IPv6 (or both IPv4/v6) ?

Nb: And yes. Have tried disabling sending capabilities to the IOS-XR
router altogether. But the the Cisco router just refuses because no
capabilities is announced from neighbor.

Nb(2): Capability option is set to 'Dynamic' when announcing to neighbor.

-- 
Regards,
Christoffer.
gpg: c8b3 82a8 a1cd cdb7 71fe  b24c c654 948f da86 becd


Software Details
================

pfSense v2.3.4
--------------
* Name: frr
* Category: net
* Version: 0.0.2
* Description: FRR routing daemon for BGP, OSPF, and OSPF6 Conflicts
with Quagga OSPF and OpenBGPD. These packages cannot be installed at the
same time.	


Debug output from Cisco IOS XR Software, Version 4.2.3[Default]
===============================================================

* NOTE(1): IPv6 network prefix replaced with '2001:db8::'

RP/0/RSP0/CPU0:Sep 26 16:49:36.532 MEST: bgp[1048]: [default-ioct] VRF
Internet: 2001:db8:::250:56ff:febd:7e57 went from Idle to Connect
RP/0/RSP0/CPU0:Sep 26 16:49:36.754 MEST: bgp[1048]: [default-iord] VRF
Internet: Received message from 2001:db8:::250:56ff:febd:7e57 with type
1, length (incl. header) 102
RP/0/RSP0/CPU0:Sep 26 16:49:36.754 MEST: bgp[1048]: [default-iord] VRF
Internet: Receive message dump for 2001:db8:::250:56ff:febd:7e57:
RP/0/RSP0/CPU0:Sep 26 16:49:36.754 MEST: bgp[1048]: [default-iord] VRF
Internet: ffff ffff ffff ffff ffff ffff ffff ffff
RP/0/RSP0/CPU0:Sep 26 16:49:36.755 MEST: bgp[1048]: [default-iord] VRF
Internet: 0066 0104 ff4c 0078 5774 0604 4902 0601
RP/0/RSP0/CPU0:Sep 26 16:49:36.755 MEST: bgp[1048]: [default-iord] VRF
Internet: 0400 0100 0102 0280 0002 0202 0002 0641
RP/0/RSP0/CPU0:Sep 26 16:49:36.755 MEST: bgp[1048]: [default-iord] VRF
Internet: 0400 00ff 4c02 0645 0400 0101 0102 0242
RP/0/RSP0/CPU0:Sep 26 16:49:36.756 MEST: bgp[1048]: [default-iord] VRF
Internet: 0002 0243 0002 1949 1715 6677 3031 2e6c
RP/0/RSP0/CPU0:Sep 26 16:49:36.756 MEST: bgp[1048]: [default-iord] VRF
Internet: 6162 2e6e 6574 7261 766e 656e 2e65 7500
RP/0/RSP0/CPU0:Sep 26 16:49:36.756 MEST: bgp[1048]: [default-iord] VRF
Internet: 0204 4002 8078
RP/0/RSP0/CPU0:Sep 26 16:49:36.756 MEST: bgp[1048]: [default-iord] VRF
Internet: Received OPEN from 2001:db8:::250:56ff:febd:7e57, version 4,
holdtime 120 secs
RP/0/RSP0/CPU0:Sep 26 16:49:36.756 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 6
RP/0/RSP0/CPU0:Sep 26 16:49:36.756 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has
MULTIPROTOCOL_EXTENSION capability for afi/safi: 1/1
RP/0/RSP0/CPU0:Sep 26 16:49:36.757 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 2
RP/0/RSP0/CPU0:Sep 26 16:49:36.757 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has ROUTE-REFRESH
capability(old) for all address-families
RP/0/RSP0/CPU0:Sep 26 16:49:36.757 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 2
RP/0/RSP0/CPU0:Sep 26 16:49:36.757 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has ROUTE-REFRESH
capability for all address-families
RP/0/RSP0/CPU0:Sep 26 16:49:36.757 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 6
RP/0/RSP0/CPU0:Sep 26 16:49:36.757 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has 4-byte AS
capability with AS 65356
RP/0/RSP0/CPU0:Sep 26 16:49:36.758 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 6
RP/0/RSP0/CPU0:Sep 26 16:49:36.758 MEST: bgp[1048]: [default-iord] VRF
Internet: 2001:db8:::250:56ff:febd:7e57 Addr-family 1/1 not supported:
Ignoring the ADDPATH capability
RP/0/RSP0/CPU0:Sep 26 16:49:36.758 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 2
RP/0/RSP0/CPU0:Sep 26 16:49:36.758 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has unrecognized
capability code: 66, length 0 (ignored)
RP/0/RSP0/CPU0:Sep 26 16:49:36.758 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 2
RP/0/RSP0/CPU0:Sep 26 16:49:36.759 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has unrecognized
capability code: 67, length 0 (ignored)
RP/0/RSP0/CPU0:Sep 26 16:49:36.759 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 25
RP/0/RSP0/CPU0:Sep 26 16:49:36.759 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has unrecognized
capability code: 73, length 23 (ignored)
RP/0/RSP0/CPU0:Sep 26 16:49:36.759 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has optional parameter
type: 2 (Capability) len: 4
RP/0/RSP0/CPU0:Sep 26 16:49:36.759 MEST: bgp[1048]: [default-iord] VRF
Internet: bgp_io_read_schedule_updgrp: NO updgrp scheduled after Open
processing: nbr=2001:db8:::250:56ff:febd:7e57, nbrfl=0x08314080
RP/0/RSP0/CPU0:Sep 26 16:49:36.759 MEST: bgp[1048]: [default-iord] VRF
Internet: 2001:db8:::250:56ff:febd:7e57 went from Connect to OpenSent
RP/0/RSP0/CPU0:Sep 26 16:49:36.760 MEST: bgp[1048]: [default-iord] VRF
Internet: Sending OPEN to 2001:db8:::250:56ff:febd:7e57, version 4, my
as: 31027, holdtime 120 seconds
RP/0/RSP0/CPU0:Sep 26 16:49:36.760 MEST: bgp[1048]: [default-iord] VRF
Internet: OPEN from 2001:db8:::250:56ff:febd:7e57 has capabilities with
no supported address-family.
RP/0/RSP0/CPU0:Sep 26 16:49:36.760 MEST: bgp[1048]: [default-iord] VRF
Internet: Sending NOTIFICATION 2/7 (unsupported/disjoint capability) to
2001:db8:::250:56ff:febd:7e57 (0 bytes: )
RP/0/RSP0/CPU0:Sep 26 16:49:36.760 MEST: bgp[1048]: [default-iord] VRF
Internet: 2001:db8:::250:56ff:febd:7e57 went from OpenSent to Closing
RP/0/RSP0/CPU0:Sep 26 16:49:36.761 MEST: bgp[1048]: [default-ioct] VRF
Internet: 2001:db8:::250:56ff:febd:7e57 send message type 3, length
(incl. header) 21
RP/0/RSP0/CPU0:Sep 26 16:49:36.761 MEST: bgp[1048]: [default-ioct] VRF
Internet: Send message dump for 2001:db8:::250:56ff:febd:7e57:
RP/0/RSP0/CPU0:Sep 26 16:49:36.761 MEST: bgp[1048]: [default-ioct] VRF
Internet: ffff ffff ffff ffff ffff ffff ffff ffff
RP/0/RSP0/CPU0:Sep 26 16:49:36.761 MEST: bgp[1048]: [default-ioct] VRF
Internet: 0015 0302 07
RP/0/RSP0/CPU0:Sep 26 16:49:36.762 MEST: bgp[1048]: [default-event] VRF
Internet: 2001:db8:::250:56ff:febd:7e57 went from Closing to Idle
RP/0/RSP0/CPU0:Sep 26 16:49:36.762 MEST: bgp[1048]: [default-event] VRF
Internet: 2001:db8:::250:56ff:febd:7e57 reset due to BGP Notification sent


Output from pfSense FRR routing daemon
======================================

* NOTE(1): IPv6 network prefix replaced with '2001:db8::'
* NOTE(2): IPv4 next-hop replaced with TEST-NET-3 address 203.0.113.4

BGP neighbor is 2001:db8::1, remote AS #ISP-ASN#, local AS 65356,
external link
  BGP version 4, remote router ID 0.0.0.0
  BGP state = Idle
  Last read 00:00:27, Last write 00:00:11
  Hold time is 120, keepalive interval is 40 seconds
  Message statistics:
    Inq depth is 0
    Outq depth is 0
                         Sent       Rcvd
    Opens:                  4          0
    Notifications:          0          4
    Updates:                0          0
    Keepalives:             0          0
    Route Refresh:          0          0
    Capability:             0          0
    Total:                  4          4
  Minimum time between advertisement runs is 0 seconds
  Update source is 2001:db8::250:56ff:febd:7e57

 For address family: IPv4 Unicast
  Not part of any update group
  Community attribute sent to this neighbor(extended)
  0 accepted prefixes

  Connections established 0; dropped 0
  Last reset 00:00:27, due to NOTIFICATION received (OPEN Message
Error/Unsupported Capability)
Local host: 2001:db8::250:56ff:febd:7e57, Local port: 57277
Foreign host: 2001:db8::1, Foreign port: 179
Nexthop: 203.0.113.4
Nexthop global: 2001:db8::250:56ff:febd:7e57
Nexthop local: fe80::250:56ff:febd:7e57
BGP connection: shared network
BGP Connect Retry Timer in Seconds: 120
Next start timer due in 5 seconds
Read thread: off  Write thread: off

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