Design Reference

mep : <node-id>
mip : (level 4)
isis manual area : 49.0001
SPBM restrictions and limitations
This section describes the restrictions and limitations associated with SPBM on VSP 4000.
RSTP and MSTP
The following list identifies restrictions and limitations associated with RSTP and MSTP:
• RSTP mode does not support SPBM.
• Because Avaya supports non-SPBM C-VLANs to also span the SPBM network, MSTP can be
provisioned in the network to provide loop-free connectivity for these non-SPBM C-VLANs.
Because all ports on the VSP 4000 system including IS-IS enabled NNI ports belong to MSTP
instance 0, Avaya recommends provisioning the non-SPBM C-VLANs in an MSTP instance
other than 0.
• SPBM NNI ports are not part of the Layer 2 VSN C-VLAN, and BPDUs are not transmitted over
the SPBM tunnel. SPBM can only guarantee loop-free topologies consisting of the NNI ports.
Avaya recommends that you always use Simple Loop Prevention Protocol (SLPP) for loop
prevention.
Note:
Avaya recommends that you deploy SLPP on C-VLANs to detect loops created by
customers in their access networks. However, SLPP is not required on B-VLANs, and it is
not supported. The B-VLAN active topology is controlled by IS-IS that has loop mitigation
and prevention capabilities built into the protocol.
• SPB internally uses spanning tree group (STG) 63 or Multiple Spanning Tree Instance (MSTI)
62. STG 63 or MSTI 62 cannot be used by another VLAN or MSTI. For non-SPB customer
networks, if you use STG 63 or MSTI 62 in the configuration, you must delete STG 63 or MSTI
62 before you can configure SPBM.
• You must configure SPBM B-VLANs on all devices in the same MSTP region. MSTP requires
this configuration to generate the correct digest.
SPBM IS-IS
The following list identifies restrictions and limitations associated with SPBM IS-IS:
• The current release does not support IP over IS-IS as defined by RFC1195. IS-IS protocol is
only to facilitate SPBM.
• The current release uses Level 1 IS-IS. The current release does not support Level 2 IS-IS.
The ACLI command show isis int-l2-contl-pkts is not supported in the current
release because the IEEE 802.1aq standard currently only defines the use of one hierarchy,
Level 1.
• The IS-IS standard defines wide (32-bit ) metrics and narrow (8-bits) metrics. The current
release supports the wide metric.
Pay special attention to the expected scaling of routes in the network when you select configuration
values for the isis l1-hello-interval and isis l1-hello-multiplier commands on IS-
SPBM design guidelines
122 Network Design Reference for Avaya VSP 4000 Series June 2015
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