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<p>Hi colleagues,</p>
<p>can anybody help me with an issue in the following configuration.</p>
<p>There is GRE over IPSec in transport mode between Linux (Ubuntu
20.04) and two other boxes - Cisco (virtual XE v17.07.01) and
Mikrotik (CHR v6). Pings are there, so IPSec policies, addresses,
connectivity is ok, but OSPF (I'm using FRR 8.1) do not work.</p>
<p>On the linux side, tcpdump shows that it sends hellos in this
interface, but both Cisco and CHR see nothing:<br>
</p>
<pre># tcpdump -i gre1 -v
[ ... ]
15:34:49.132222 IP (tos 0xc0, ttl 1, id 15017, offset 0, flags [none], proto OSPF (89), length 68)
my_linux > ospf-all.mcast.net: OSPFv2, Hello, length 48
Router-ID x.x.x.x, Backbone Area, Authentication Type: none (0)
Options [External]
Hello Timer 10s, Dead Timer 40s, Mask 255.255.255.252, Priority 1
Neighbor List:
100.100.8.1
</pre>
<p>Cisco:</p>
<pre>Mar 11 15:31:33.522: OSPF-1 HELLO Tu8: Send hello to 224.0.0.5 area 0 from 100.99.0.65
Mar 11 15:31:42.586: OSPF-1 HELLO Tu8: Send hello to 224.0.0.5 area 0 from 100.99.0.65
Mar 11 15:31:51.641: OSPF-1 HELLO Tu8: Send hello to 224.0.0.5 area 0 from 100.99.0.65
</pre>
<p>Mikrotik (using packet sniffer) also see nothing on input.</p>
<p>Definitely, the issue is on Linux side but I can't realize, where
exactly.<br>
</p>
Linux side (mtu is same, multicast switched on):
<pre>6: gre1@NONE: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1400 qdisc noqueue state UNKNOWN group default qlen 1000
link/gre x.x.x.x peer x.x.x.y
inet 100.99.0.66/30 brd 100.99.0.67 scope global gre1
valid_lft forever preferred_lft forever
vtysh#sh run
[ ... ]
interface gre1
ip ospf cost 5
ip ospf mtu-ignore
vtysh#sh ip ospf interface gre1
gre1 is up
ifindex 6, MTU 1400 bytes, BW 0 Mbit <UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>
Internet Address 100.99.0.66/30, Broadcast 100.99.0.67, Area 0.0.0.0
MTU mismatch detection: disabled
Router ID x.x.x.x, Network Type POINTOPOINT, Cost: 5
Transmit Delay is 1 sec, State Point-To-Point, Priority 1
No backup designated router on this network
Multicast group memberships: OSPFAllRouters
Timer intervals configured, Hello 10s, Dead 40s, Wait 40s, Retransmit 5
Hello due in 8.701s
Neighbor Count is 1, Adjacent neighbor count is 0
vtysh#sh ip ospf neigh
Neighbor ID Pri State Dead Time Address Interface RXmtL RqstL DBsmL
100.100.8.1 1 Init/DROther 37.960s 100.99.0.65 gre1:100.99.0.66 0 0 0
host# ip maddress
[ ... ]
6: gre1
inet 224.0.0.5
inet 224.0.0.1</pre>
<p>What I miss in the Linux configuration?<br>
</p>
<p>Cisco configuration is for reference:</p>
<pre>interface Tunnel8
description HZF
ip address 100.99.0.65 255.255.255.252
ip mtu 1400
ip ospf network point-to-point
ip ospf cost 5
tunnel source GigabitEthernet1
tunnel destination x.x.x.x
Tunnel8 is up, line protocol is up
Internet Address 100.99.0.65/30, Interface ID 20, Area 0
Attached via Network Statement
Process ID 1, Router ID 100.100.8.1, Network Type POINT_TO_POINT, Cost: 5
Topology-MTID Cost Disabled Shutdown Topology Name
0 5 no no Base
Transmit Delay is 1 sec, State POINT_TO_POINT
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:04
Supports Link-local Signaling (LLS)
Cisco NSF helper support enabled
IETF NSF helper support enabled
Can not be protected by per-prefix Loop-Free FastReroute
Can be used for per-prefix Loop-Free FastReroute repair paths
Not Protected by per-prefix TI-LFA
Index 1/8/8, flood queue length 0
Next 0x0(0)/0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 38
Last flood scan time is 0 msec, maximum is 1 msec
Neighbor Count is 0, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
</pre>
<p>Thank you for any recommendations.<br>
</p>
<pre class="moz-signature" cols="72">--
Volodymyr Litovka
"Vision without Execution is Hallucination." -- Thomas Edison</pre>
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