zebra: fix problem with SVI MAC not being sent to BGP
For MH the SVI MAC is advertised to prevent flooding of ARP replies.
But because of a bug the SVI MAC was being added to the zebra database
but not sent to bgpd for advertising.
zebra: drop the SVI MAC cleanup done as a part of interface delete
As a part of FRR shutdown interfaces are force flushed (in an arbitary
order). Interfaces are already down at that point i.e. resources like
SVI-MAC have already been released. Attempting to clean it up again
as a part of the force-flush was resulting in access of freed up memory -
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
==26457== Thread 1:
==26457== Invalid read of size 8
==26457== at 0x1AE6B0: zebra_evpn_acc_bd_svi_set (zebra_evpn_mh.c:606)
==26457== by 0x1B1460: zebra_evpn_if_cleanup (zebra_evpn_mh.c:1040)
==26457== by 0x13CA69: if_zebra_delete_hook (interface.c:244)
==26457== by 0x48A0E34: hook_call_if_del (if.c:59)
==26457== by 0x48A0E34: if_delete_retain (if.c:290)
==26457== by 0x48A2F94: if_delete (if.c:313)
==26457== by 0x48A3169: if_terminate (if.c:1217)
==26457== by 0x48E0024: vrf_delete (vrf.c:254)
==26457== by 0x48E0024: vrf_delete (vrf.c:225)
==26457== by 0x48E02FE: vrf_terminate (vrf.c:551)
==26457== by 0x1442E1: sigint (main.c:203)
==26457== by 0x1442E1: sigint (main.c:141)
==26457== by 0x48CF862: quagga_sigevent_process (sigevent.c:103)
==26457== by 0x48DD324: thread_fetch (thread.c:1404)
==26457== by 0x48A926A: frr_run (libfrr.c:1122)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
(gdb) bt
(gdb) fr 5
1037 zebra/zebra_evpn_mh.c: No such file or directory.
(gdb) p zif->ifp->name
$2 = "vlan131", '\000' <repeats 12 times>
(gdb) p zif->link->info
$5 = (void *) 0x1
(gdb) p/x zif->ifp->flags
$7 = 0x1002
(gdb)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Chirag Shah [Tue, 24 Nov 2020 20:22:49 +0000 (12:22 -0800)]
zebra: prevent crash in evpn if cleanup
zebra crash is seen while cleaning up evpn interface
during shutdown event.
evpn interface clean up is called from vrf_delete callback
(gdb) frame 4
(is_up=false, br_zif=0x0, vlan_zif=0x557f31fb36f0) at zebra/zebra_evpn_mh.c:614
614 zebra/zebra_evpn_mh.c: No such file or directory.
(gdb) p tmp_br_zif
$1 = (struct zebra_if *) 0x0
(gdb) p vlan_zif->link
$2 = (struct interface *) 0x557f31fb2d40
(gdb) p vlan_zif->link->info
$3 = (void *) 0x0
(gdb) p zebra_if->ifp->name
No symbol "zebra_if" in current context.
(gdb) p vlan_zif->ifp->name
$4 = "peerlink-3.4094\000\000\000\000"
zebra: changes to advertise SVI mac by default if evpn-mh is enabled
Added support for advertising SVI MAC if EVPN-MH is enabled.
In the case of EVPN MH arp replies from an attached server can be sent to
the ES-peer. To prevent flooding of the reply the SVI MAC needs to be
advertised by default.
Note:
advertise-svi-ip could have been used as an alternate way to advertise
SVI MAC. However that config cannot be turned on if SVI IPs are
re-used (which is done to avoid wasting IP addresses in a subnet).
zebra: fix problem with SVI IP being advertised even if disabled
SVI IP is being advertised unconditionally i.e. even if disabled (and
that is the default config). This can be problematic when the SVI address
is re-used across racks.
Added the user config condition in all the relevant places where the
SVI advertisement is triggered.
lynne [Wed, 17 Feb 2021 14:21:43 +0000 (09:21 -0500)]
ospf6d: Update logs that indicate why ospf6 adjacency is not coming up.
Add more details to these logs to help make it easier to determine why
ospf6 adjacency is not coming up. Also make these logs show up without
having to turn on debug logging, again making it easier to debug the
misconfiguration.
Mark Stapp [Thu, 18 Feb 2021 14:37:09 +0000 (09:37 -0500)]
lib: don't awaken from poll for every timer
Only ask the event-loop poll() to awaken if a newly-added timer
actually might have changed the required timeout. Also compute
timer deadline outside of mutex locks.
Donald Sharp [Thu, 18 Feb 2021 11:55:29 +0000 (06:55 -0500)]
bgpd: Fix crash when we don't have a nexthop
Recent changes to allow bgpd to handle v6 LL slightly
differently in the nexthop tracking code has not
interacted well with the blackhole nexthop change
for peers. Modify the code to do the right thing
Pat Ruddy [Sun, 14 Feb 2021 12:09:55 +0000 (12:09 +0000)]
bgpd, lib: add oid2in6_addr utility and use it
The existing code was using the oid2in_addr API to copy IPv6
addresses passing an IPv6 length. Create a utility to do this
properly and avoid annoying coverity with type checking.
Donald Sharp [Thu, 17 Dec 2020 14:46:30 +0000 (09:46 -0500)]
bgpd: Switch LL nexthop tracking to be interface based
bgp is currently registering v6 LL as nexthops to be tracked
from zebra. This presents several problems.
a) zebra does not properly track multiple prefixes that match
the same route properly at this point in time.
b) BGP was receiving nexthops that were just incorrect because
of (a).
c) When a nexthop changed that really didn't affect the v6 LL
we were responding incorrectly because of this
Modify the code such that bgp nexthop tracking notices that
we are trying to register a v6 LL. When we do so, shortcut
and watch interface up/down events for this v6 LL and do
the work when an interface goes up / down for this type
of tracking.
Igor Ryzhov [Wed, 17 Feb 2021 12:06:20 +0000 (15:06 +0300)]
staticd: fix vrf enabling
When enabling the VRF, we should not install the nexthops that rely on
non-existent VRF.
For example, if we have route "1.1.1.0/24 2.2.2.2 vrf red nexthop-vrf blue",
and VRF red is enabled, we should not install it if VRF blue doesn't exist.
Igor Ryzhov [Wed, 17 Feb 2021 11:19:40 +0000 (14:19 +0300)]
staticd: fix nexthop creation and installation
Currently, staticd creates a VRF for the nexthop it is trying to install.
Later, when this nexthop is deleted, the VRF stays in the system and can
not be deleted by the user because "no vrf" command doesn't work for this
VRF because it was not created through northbound code.
There is no need to create the VRF. Just set nh_vrf_id to VRF_UNKNOWN
when the VRF doesn't exist.
Donald Sharp [Tue, 16 Feb 2021 20:54:08 +0000 (15:54 -0500)]
zebra: use AF_INET for protocol family
When looking up the conversion from kernel protocol to
internal protocol family make sure we use the correct
AF_INET( what the kernel uses ) instead of AFI_IP (which
is what FRR uses ).
Routes from OSPF will show up from the kernel as OSPF6 instead of
OSPF. Which will cause mayhem
Ticket: CM-33306 Signed-off-by: Donald Sharp <sharpd@nvidia.com>
Mark Stapp [Mon, 15 Feb 2021 18:59:02 +0000 (13:59 -0500)]
build: detect ICC, only try ICC options if ICC
Some ICC command-line options can cause confusion for other
compilers; test for ICC specifically, and only try to use those
options if ICC is being used.
Donald Sharp [Sun, 14 Feb 2021 21:08:07 +0000 (16:08 -0500)]
bgpd: Prevent store but never read of i
The new bgp_mplsvpn_snmp.c code increments i and
never uses that value. Comment the code out
to make the clang SA analyzer happy. Shouldn't
be a problem since this code will never probably
be touched again(ha!).
Donald Sharp [Sun, 14 Feb 2021 21:04:16 +0000 (16:04 -0500)]
nhrpd: Fix clang SA about null deref
Clang was complaining when running SA that the nhrpd_privs.change
function was null. It just does not fully understand how things
are setup. Add a assert to make it happy.
Donatas Abraitis [Sun, 14 Feb 2021 15:49:19 +0000 (17:49 +0200)]
bgpd: Check for peer->su_remote if not NULL when handling IPv6 nexthop
```
(gdb) bt
0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
1 0x00007fe57ca4a42a in __GI_abort () at abort.c:89
2 0x00007fe57ddd1935 in core_handler (signo=6, siginfo=0x7ffc81067570, context=<optimized out>) at lib/sigevent.c:255
3 <signal handler called>
4 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
5 0x00007fe57ca4a42a in __GI_abort () at abort.c:89
6 0x00007fe57ddd1935 in core_handler (signo=11, siginfo=0x7ffc81067e30, context=<optimized out>) at lib/sigevent.c:255
7 <signal handler called>
8 0x000055a7b25b923f in bgp_path_info_to_ipv6_nexthop (ifindex=ifindex@entry=0x7ffc810683c0, path=<optimized out>, path=<optimized out>) at bgpd/bgp_zebra.c:909
9 0x000055a7b25bb2e5 in bgp_zebra_announce (dest=dest@entry=0x55a7b5239c10, p=p@entry=0x55a7b5239c10, info=info@entry=0x55a7b5239cd0, bgp=bgp@entry=0x55a7b518b090, afi=afi@entry=AFI_IP6, safi=safi@entry=SAFI_UNICAST) at bgpd/bgp_zebra.c:1358
10 0x000055a7b256af6a in bgp_process_main_one (bgp=0x55a7b518b090, dest=0x55a7b5239c10, afi=AFI_IP6, safi=SAFI_UNICAST) at bgpd/bgp_route.c:2918
11 0x000055a7b256b0ee in bgp_process_wq (wq=<optimized out>, data=0x55a7b5221800) at bgpd/bgp_route.c:3027
12 0x00007fe57ddea2e0 in work_queue_run (thread=0x7ffc8106cd60) at lib/workqueue.c:291
13 0x00007fe57dde0781 in thread_call (thread=thread@entry=0x7ffc8106cd60) at lib/thread.c:1684
14 0x00007fe57dda84b8 in frr_run (master=0x55a7b48aaf00) at lib/libfrr.c:1126
15 0x000055a7b250a7da in main (argc=<optimized out>, argv=<optimized out>) at bgpd/bgp_main.c:540
(gdb)
```
This crashes with configs like:
```
router bgp 65534
no bgp ebgp-requires-policy
no bgp network import-check
!
address-family ipv6 unicast
import vrf donatas <<<<<< Crashes when entering this command
exit-address-family
!
router bgp 65534 vrf donatas
no bgp ebgp-requires-policy
no bgp network import-check
neighbor fe80::c15a:ddab:1689:db86 remote-as 65025
neighbor fe80::c15a:ddab:1689:db86 interface eth2
neighbor fe80::c15a:ddab:1689:db86 update-source eth2
neighbor fe80::c15a:ddab:1689:db86 capability extended-nexthop
!
address-family ipv6 unicast
network 2a02:face::/32 <<<<<< Crashes due to static networks
neighbor fe80::c15a:ddab:1689:db86 activate
exit-address-family
!
```
Locally configured routes do not have peer->su_remote.
```
exit1-debian-9# show bgp ipv6 unicast
BGP table version is 3, local router ID is 192.168.100.1, vrf id 0
Default local pref 100, local AS 65534
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
*> 2a02:abc::/64 fe80::c15a:ddab:1689:db86@5<
0 65025 i
2a02:face::/32 ::@5< 0 32768 i
Displayed 2 routes and 2 total paths
exit1-debian-9#
Donald Sharp [Thu, 11 Feb 2021 14:54:34 +0000 (09:54 -0500)]
bgpd: Blackhole nexthops are not reachable
When bgp registers for a nexthop that is not reachable due
to the nexthop pointing to a blackhole, bgp is never going
to be able to reach it when attempting to open a connection.
Broken behavior:
<show bgp nexthop>
192.168.161.204 valid [IGP metric 0], #paths 0, peer 192.168.161.204
blackhole
Last update: Thu Feb 11 09:46:10 2021
eva# show bgp ipv4 uni summ fail
BGP router identifier 10.10.3.11, local AS number 3235 vrf-id 0
BGP table version 40
RIB entries 78, using 14 KiB of memory
Peers 2, using 54 KiB of memory
Neighbor EstdCnt DropCnt ResetTime Reason
192.168.161.204 0 0 never Waiting for peer OPEN
The log file fills up with this type of message:
2021-02-09T18:53:11.653433+00:00 nq-sjc6c-cor-01 bgpd[6548]: can't connect to 24.51.27.241 fd 26 : Invalid argument
2021-02-09T18:53:21.654005+00:00 nq-sjc6c-cor-01 bgpd[6548]: can't connect to 24.51.27.241 fd 26 : Invalid argument
2021-02-09T18:53:31.654381+00:00 nq-sjc6c-cor-01 bgpd[6548]: can't connect to 24.51.27.241 fd 26 : Invalid argument
2021-02-09T18:53:41.654729+00:00 nq-sjc6c-cor-01 bgpd[6548]: can't connect to 24.51.27.241 fd 26 : Invalid argument
2021-02-09T18:53:51.655147+00:00 nq-sjc6c-cor-01 bgpd[6548]: can't connect to 24.51.27.241 fd 26 : Invalid argument
As that the connect to a blackhole is correctly rejected by the kernel
Fixed behavior:
eva# show bgp ipv4 uni summ
BGP router identifier 10.10.3.11, local AS number 3235 vrf-id 0
BGP table version 40
RIB entries 78, using 14 KiB of memory
Peers 2, using 54 KiB of memory
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd PfxSnt Desc
annie(192.168.161.2) 4 64539 126264 39 0 0 0 00:01:36 38 40 N/A
192.168.161.178 4 0 0 0 0 0 0 never Active 0 N/A
Total number of neighbors 2
eva# show bgp ipv4 uni summ fail
BGP router identifier 10.10.3.11, local AS number 3235 vrf-id 0
BGP table version 40
RIB entries 78, using 14 KiB of memory
Peers 2, using 54 KiB of memory
Neighbor EstdCnt DropCnt ResetTime Reason
192.168.161.178 0 0 never Waiting for NHT
Total number of neighbors 2
eva# show bgp nexthop
Current BGP nexthop cache:
192.168.161.2 valid [IGP metric 0], #paths 38, peer 192.168.161.2
if enp39s0
Last update: Thu Feb 11 09:52:05 2021
192.168.161.131 valid [IGP metric 0], #paths 0, peer 192.168.161.131
if enp39s0
Last update: Thu Feb 11 09:52:05 2021
192.168.161.178 invalid, #paths 0, peer 192.168.161.178
Must be Connected
Last update: Thu Feb 11 09:53:37 2021
eva#
Trey Aspelund [Sat, 13 Feb 2021 05:08:19 +0000 (05:08 +0000)]
ospfd: cleanup ospf_flood debugs
Replaces some hard-coded function names with __func__,
adds some additional references to neighbor/interface,
and cleans up some debug strings to be more readable.
Quentin Young [Thu, 11 Feb 2021 23:54:27 +0000 (18:54 -0500)]
bgpd: send correct BMP down message when nht fails
When sending BMP messages for a status change event for a peer whose NHT
has failed, we were sending a Peer Down Reason Code of 1 (Local system
closed, NOTIFICATION follows) with no NOTIFICAION PDU (because there was
none). This is wrong. Also, the reason code of 1 is semantically off, it
should be 2 (Local system closed, FSM event follows).
This patch:
- adds definitions of all BGP FSM event codes per RFC4271
- changes the BMP reason code emitted when a peer changes state due to
NHT failure to 2 and encodes FSM event 18 (TcpConnectionFails)
- changes the catch-all case where we have not yet
implemented the appropriate BMP response to indicate reason code 2
with FSM event 0 (no relevant Event code is defined).
These changes ought to prevent the BMP session from being torn down due
to an improperly formatted message.
Signed-off-by: Quentin Young <qlyoung@qlyoung.net>
David Lamparter [Thu, 4 Feb 2021 21:27:11 +0000 (22:27 +0100)]
lib: de-uglify `-t` option + `log stdout` combo
The logging code writes log messages with a `\n` line ending, meanwhile
the VTY code switches it so you need `\r\n`...
And we don't flush the newline after executing a command either.
After this patch, starting daemons like `zebra/zebra -t` should provide
a nice development/debugging experience with a VTY open right there on
stdio and `log stdout` interspersed.
(This is already documented in the man pages, it just looked like sh*t
previously since the log messages didn't newline correctly.)
Signed-off-by: David Lamparter <equinox@diac24.net>
David Lamparter [Thu, 4 Feb 2021 21:25:49 +0000 (22:25 +0100)]
lib: memorize what fds were open at startup
... in case the user does something like `zebra 3>logfile`. Also useful
for some module purposes, maybe even feeding config at some point in the
future.
Signed-off-by: David Lamparter <equinox@diac24.net>
David Teach [Thu, 11 Feb 2021 20:44:00 +0000 (20:44 +0000)]
bgpd: Add Support for rfc 8050 MRT add-path
- Rfc 8050 adds support for BGP NLRI that carry path identifiers. this commit adds that support to FRR
- Updated bgp_dump.h to include new sub-type values
- Updated bgp_dump.c to check for add_path af_caps in the peer struct.
- Updated bgp_dump.c to use the proper sub-type values upon detection of add-path af_caps
- Updated bgp_dump.c to properly dump the path_id wen present.
Signed-off-by: David Teach <dteach@routeviews.org>
Trey Aspelund [Tue, 9 Feb 2021 01:10:03 +0000 (01:10 +0000)]
bgpd: fix empty advertised-routes for 2-tier safis
'show bgp ipv[46] vpn neighbors ... advertised-routes' was displaying
empty output due to new command syntax using show_adj_routes() which
assumed each bgp_table was single-tier (not nested). This fixes that
assumption for safis with a two-tier bgp_table (SAFI_MPLS_VPN,
SAFI_ENCAP, and SAFI_EVPN).
Before:
ub18# show bgp ipv6 vpn neighbors 2001:db8:cafe::2 advertised-routes
ub18#
After:
ub20# show bgp ipv6 vpn neighbors 2001:db8:cafe::1 advertised-routes
BGP table version is 2, local router ID is 100.64.0.222, 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
Route Distinguisher: 30:30
*> 2::2/128 :: 0 100 32768 i
*> 2::22/128 :: 0 100 32768 i
Route Distinguisher: 33:33
*> 2::2/128 :: 0 100 32768 i
*> 2::22/128 :: 0 100 32768 i
Olivier Dugeon [Wed, 10 Feb 2021 18:20:24 +0000 (19:20 +0100)]
ospfd: Debug race condition in Segment Routing
Issue #7926 hilight a race condition in Segment Routing processing.
The problem occurs when Router Information Opaque LSA is received late, in
particular after SPF run and after ospf_sr_nhlfe_update() was called. This
scenario is unfrequent and takes place due to a slow DR election.
In this particular case, SR Prefix are handle but not fully fill. In fact,
SRGB for the nexthop is not yet received and thus, output label could not
be computed.
When Router Information Opaque LSA is received and processed, if the
corresponding SR node is a direct neighbor of the self node, update_out_nhlfe()
is called against all SR nodes to adjust SR prefix if the next hop is the new
SR node. The function wrongly computes output label and configure a bad MPLS
LFIB entries.
Another way to hilight the problem is to change through CLI the SRGB of a node
and look to MPLS LFIB of direct neighbor, in particular those who announce
EXPLICIT NULL Prefix SID.
This patch correct the update_out_nhlfe() function by calling the appropriate
function (sr_prefix_out_label() instead of index2label()) to compute the output
label.
Some log debugs were adjusted and unused prefix route table was removed too.
Donald Sharp [Thu, 11 Feb 2021 12:31:05 +0000 (07:31 -0500)]
ospfd: Prevent duplicate packet read in certain vrf situations
Currently if the sysctl net.ipv4.raw_l3mdev_accept is 1, packets
destined to a specific vrf also end up being delivered to the default
vrf. We will see logs like this in ospf:
2021/02/10 21:17:05.245727 OSPF: ospf_recv_packet: fd 20(default) on interface 1265(swp1s1.26)
2021/02/10 21:17:05.245740 OSPF: Hello received from [9.9.36.12] via [swp1s1.26:200.254.26.13]
2021/02/10 21:17:05.245741 OSPF: src [200.254.26.14],
2021/02/10 21:17:05.245743 OSPF: dst [224.0.0.5]
2021/02/10 21:17:05.245769 OSPF: ospf_recv_packet: fd 45(vrf1036) on interface 1265(swp1s1.26)
2021/02/10 21:17:05.245774 OSPF: Hello received from [9.9.36.12] via [swp1s1.26:200.254.26.13]
2021/02/10 21:17:05.245775 OSPF: src [200.254.26.14],
2021/02/10 21:17:05.245777 OSPF: dst [224.0.0.5]
This really really makes ospf unhappy in the vrf we are running in.
I am approaching the problem by just dropping the packet if read in the
default vrf because of:
lib: Allow bgp to always create a listen socket for the vrf
Effectively if we have `router ospf vrf BLUE` but no ospf running
in the default vrf, we will not have a listener and that would
require a fundamental change in our approach to handle the ospf->fd
at a global level. I think this is less than ideal at the moment
but it will get us moving again and allow FRR to work with
a bunch of vrf's and ospf neighbors.
Philippe Guibert [Thu, 23 Jul 2020 06:57:05 +0000 (08:57 +0200)]
nhrpd: shortcut routes installed with nexthop.
Previously, when a shortcut entry was created, its associated route was
created on system, with no nexthop, only gre device. eg:
[..]
N>* 192.168.2.0/24 [10/0] is directly connected, gre1, 00:01:04 <--- can not be resolved
[..]
Type Prefix Via Identity
dynamic 192.168.2.0/24 10.255.255.2 <---- correct
This situation was forcing neighbor resolution on the first outgoing packet matching the route entry. for instance 192.168.2.1 could not be resolved at link layer, and was going to fail. Instead, nhrp nexthop should have been used.
This is what this commit intends to do, that is to say that when a
shortcut is installed by nhrp, the associated nexthop entry is used.
[..]
N>* 192.168.2.0/24 [10/0] via 10.255.255.2, gre1 onlink, 00:00:31
Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
Soman K S [Wed, 10 Feb 2021 11:15:22 +0000 (16:45 +0530)]
ospf6d : fix issue in ecmp inter area route
Issue: When a path in the inter area ecmp route is deleted, the route is removed
Fix: The fix is to remove the specific path from the inter area route using
ospf6_abr_old_route_remove() when abr route entry is not found.
In the function ospf6_abr_old_route_remove() the path to be removed needs
to match adv router and link state ID
Fixed memory leak in ospf6_intra_prefix_update_route_origin() caused by
route node lock not getting released.
Igor Ryzhov [Tue, 9 Feb 2021 18:38:45 +0000 (21:38 +0300)]
vrf: mark vrf as configured when entering vrf node
The VRF must be marked as configured when user enters "vrf NAME" command.
Otherwise, the following problem occurs:
`ip link add red type vrf table 1`
VRF structure is allocated.
`vtysh -c "conf t" -c "vrf red"`
`lib_vrf_create` is called, and pointer to the VRF structure is stored
to the nb_config_entry.
`ip link del red`
VRF structure is freed (because it is not marked as configured), but
the pointer is still stored in the nb_config_entry.
`vtysh -c "conf t" -c "no vrf red"`
Nothing happens, because VRF structure doesn't exist. It means that
`lib_vrf_destroy` is not called, and nb_config_entry still exists in
the running config with incorrect pointer.
`ip link add red type vrf table 1`
New VRF structure is allocated.
`vtysh -c "conf t" -c "vrf red"`
`lib_vrf_create` is NOT called, because the nb_config_entry for that
VRF name still exists in the running config.
After that all NB commands for this VRF will use incorrect pointer to
the freed VRF structure.