Configuration Guide

Table Of Contents
Fabric Extend (FE) considerations
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October 2021
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vIST session over Fabric Extend logical interface is not supported in software release 5.0 release.
However Logical interface tunnels can be terminated/originated to other BEBs from vIST peers.
FE ISIS logical interface over IP and ISIS logical interface over VLANs will not be supported on
the same node simultaneously.
Egress shaping over Logical interface is not supported in this release.
Do not fragment (DF) bit will not be set in the IP header of VXLAN encapsulation for data
packets.
MTU will not be auto-discovered over IP tunnel and tunnel MTU will not be automatically set to the
auto-discovered value.
Encryption
o Switch based MACSEC encryption cannot be used with Fabric Extend IP.
FE Logical interface Tunnel IP addresses, i.e. local and loopback interfaces used for the FE
tunneling, cannot be reachable via ISIS IP shortcuts route and it has to be prevented by user by
applying appropriate ISIS accept policies or using separate VRF for reachability to tunnel
destination IPs.
In FE solution using VSP 4000 with ONA, the ONA management VLAN always has to be in the
GRT
Fragmentation/re-assembly is supported on FE tunnels only between VSP 4000’s with ONA’s.
Dynamic change of MTU on ONA resulting in mismatch of MTU config between VSP 4000 and
VSP 8000/7200 will lead to traffic loss while adjacency remains operational
No fragmentation/re-assembly support in L2 core or VID tunneling solution. Minimum MTU of
1544 bytes should be supported by underlying L2 core.
In FE solution using VSP 4000 with ONA, MTU can be updated while logical interface is admin
up. There will be a minimal transient loss of traffic while the MTU is updated.
FE configuration will not be allowed if User has only configured Single B-VLAN in the SPBM. Both
primary and secondary B-VLAN are mandatory for the Fabric extend feature to work.
In Fabric extend L2 core solution ISIS logical interface vids cannot be same value as that of
SPBm B-VLANs.
In Fabric extend L2 core solution ISIS logical interfaces cannot be configured on Brouter
interface.
User created IP based filters (ACL/ACE) will not work on the physical interface with the FE
VXLAN tunnels terminate