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Cisco IOS XE 3S Release Notes for the Cisco ASR 903 Router
OL-26630-12
Chapter
Limitations and Restrictions
•
When you install a Gigabit Ethernet IM in the topmost interface module slot (slot 5), the last
interface (interface GigabitEthernet0/5/0) is not operational; the port is reserved for internal
communication.
• When you configure the copper and SFP Gigabit Ethernet interface modules on a router with
redundant RSPs, the
speed and duplex commands are not visible in interface configuration mode
until you apply a shutdown / no shutdown to the interface.
•
Fragmentation is not supported with Multicast traffic.
IPv6 Limitations
The following limitation applies when using IPv6 on the Cisco ASR 903 Router:
• IPv6 Neighbor Discovery (ND) cache timer expiry is 4 hours. To prevent the neighbour adjacency
from being deleted after the timer expires:
–
configure hardware based BFD sessions with the neighbours, or
– configure static IPv6 neighbours, or
–
configure the ipv6 nd cache expire timer refresh command.
IS-IS Limitations
• IS-IS over IPv6 is not supported on VRF instances.
•
Only one IS-IS process is permitted when you configure IS-IS with the address-family ipv6 and
bfd-all-interfaces commands.
• The IS-IS total and per-stream convergence time increases as the number of prefixes increases.
MLPPP Limitations
The following limitations apply when using MLPPP on the Cisco ASR 903 Router:
•
All links in an MLPPP bundle must be on the same interface module.
• All links in an MLPPP bundle must be of the same bandwidth.
•
The Cisco ASR 903 Router supports a maximum of 8 links per bundle
• To change the MLPPP bundle fragmentation mode between enabled and disabled, perform a
shutdown / no shutdown on the bundle.
•
LFI is not supported
•
Multiclass MLP is not supported
•
The Cisco ASR 903 Router supports MLPPP statistics with the following limitations:
–
Packet counters on the bundle display the number of fragments rather than packets.
–
Control packets are accounted on the bundle.
• If you increase the maximum transmission unit (MTU) size on an MLPPP interface to a value higher
than the maximum received reconstructed unit (MRRU) value on the peer interface, this can bring
the MLPPP tunnel down. To restore the tunnel, perform a shutdown/no shutdown on the interface.
MPLS VPN Limitation
•
MPLS VPN (L3VPN) Fragmentation does not function properly if an access interface has a higher
MTU value than a core interface. To ensure that fragmentation functions correctly, configure the
core interface MTU with a value that exceeds the access interface MTU and relevant headers.