Configuration Guide

Table Of Contents
©2021 Extreme Networks, Inc. All ri
g
hts reserved
October 2021
381
23. Restrictions and Limitations
23.1
STP/RSTP/MSTP
SPB is not supported in RSTP mode
C-VLAN level loop across SPB NNI ports can’t be detected and need to be solved at provisional level.
SPB NNI ports are not part of L2VSN C-VLAN and BPDU are not transmitted over the SPB tunnel.
SPB can only guarantee loop-free topologies consisting of the NNI ports.
SPB uses STG 63/MSTI 62 internally so 62/63 can’t be used by other VLAN/MSTI. If STG/MSTI 62/63
is used in the configuration on non-SPB customer network, then STG/MSTI 61 is used internally.
When an ISIS interface is created, MSTP is automatically disabled for MSTI-62 allowing traffic for the
B-VLAN to be forwarded and not blocked. This also allows traffic for other VLANs other than the
BVLANs to co-exist with SPBM on the same interface.
SPB B-VLANs need to be configured on all bridges as well in the same MSTP region. This is required
by MSTP itself to generate the correct digest if MSTP is in use and configured with Regional settings.
In MSTP mode, when a C-VLAN is created on the BEB, make sure the same VLAN is created on all
switches in the same MSTP region to have correct digest.
23.2
SPB IS-IS
IP IS-IS
IP over IS-IS is not supported. IS-IS protocol is only to facilitate SPB.
Level 1 IS-IS Only
SPB only use level 1 IS-IS. Level 2 IS-IS is currently not supported.
Wide Metric Only
IS-IS standard defines wide (32bit) metric and narrow (8 bits) metrics. Only wide metric is supported.
IS-IS HA – ERS 8800 and VSP 9000
SPB support full HA (High Availability). SPB and IS-IS configuration and dynamic information
(adjacencies, LSPs etc.) are all HA synced to the standby CPU to ensure seamless switchover.
Switching between the CPUs is very quick - there is a sub-second second gap between the active CPU
down and the standby CPU up.
To avoid IS-IS adjacencies bounce during switchover, the default hello interval value of 9 seconds and
hello multiple of 3 are good for most normal configurations. They may need to be increased depending on
overall system load.
IS-IS sys-name
By default, the IS-IS sys-name is derived from the global system name setting. If you do set the IS-IS sys-
name parameter, please ensure that a different value from the global system name is used.