Hi everyone,
We've encountered an IPv6 connectivity issue on an RBSXTR when connected to LTE networks.
The LTE APN is configured to use both IPv4 and IPv6 (IP Type = Auto).
What happens
1. IPv6 address is assigned successfully
After connecting to the LTE network, the device receives an IPv6 prefix and generates a global IPv6 address on the lte1 interface:
[root@SXT] > /ipv6/address/print where (global and interface=lte1)
Flags: D - DYNAMIC; G - GLOBAL
Columns: ADDRESS, INTERFACE, VRF, ADVERTISE, VALID, PREFERRED
# ADDRESS INTERFACE VRF ADVERTISE VALID PREFERRED
7 DG 2001:db8::200:5eff:fe00:53fd/64 lte1 main no 54m46s 24m46s
2. Address lifetime starts counting down
The VALID and PREFERRED lifetimes begin counting down from approximately:
-
VALID: 00:59:59
-
PREFERRED: 00:29:59
3. When the Preferred Lifetime expires
Once PREFERRED reaches 00:00:00, WinBox starts displaying an incrementing timer (00:00:01, 00:00:02, ...), while the address still appears with only the DG flags.
However, the CLI shows different information:
-
the PREFERRED column disappears;
-
the address is marked as DGd, where d means DEPRECATED.
[root@SXT] > /ipv6/address/print where (global and interface=lte1)
Flags: D - DYNAMIC; G - GLOBAL; d - DEPRECATED
Columns: ADDRESS, INTERFACE, VRF, ADVERTISE, VALID
# ADDRESS INTERFACE VRF ADVERTISE VALID
0 DGd 2001:db8::200:5eff:fe00:53fd/64 lte1 main no 27m35s
Interestingly, WinBox does not indicate that the address is deprecated, while the CLI does.
4. When the Valid Lifetime expires
Once VALID reaches 00:00:00, if the /ipv6/address window in WinBox is closed and reopened, both VALID and PREFERRED reappear and start increasing from approximately 2d 01:30:00.
The CLI, however, still shows:
[root@SXT] > /ipv6/address/print where (global and interface=lte1)
Flags: D - DYNAMIC; G - GLOBAL; d - DEPRECATED
Columns: ADDRESS, INTERFACE, VRF, ADVERTISE
# ADDRESS INTERFACE VRF ADVERTISE
0 DGd 2001:db8::200:5eff:fe00:53fd/64 lte1 main no
The actual problem
After approximately one hour, IPv6 connectivity stops working completely.
The global IPv6 address remains assigned to the interface, but no IPv6 traffic is possible anymore.
IPv6 starts working again only after reconnecting the LTE connection.
Additional information
[root@SXT] > /system/routerboard/print
routerboard: yes
board-name: SXT R
model: RBSXTR
revision: r3
firmware-type: qca9531L
factory-firmware: 6.45.9
current-firmware: 7.23.2
upgrade-firmware: 7.23.2
[root@SXT] > /ipv6/dhcp-client/print detail
Flags: D - DYNAMIC; X - DISABLED, I - INVALID
(no DHCPv6 client is present)
[root@SXT] > /ipv6/nd/print
Flags: X - DISABLED, I - INVALID; * - DEFAULT
0 X* interface=all ...
1 X interface=lte1 ...
Testing performed
The issue has been reproduced:
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with SIM cards from multiple mobile operators;
-
on different LTE networks;
-
in several countries.
This suggests that the problem is not specific to a particular carrier.
Questions
-
Is this expected RouterOS behavior?
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Should RouterOS automatically renew the IPv6 prefix before the Preferred/Valid lifetimes expire?
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Could this be a RouterOS bug or an LTE modem firmware issue?
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Has anyone experienced the same behavior?