User Guide

Table Of Contents
Link Aggregation 1087
On a failover from the primary MLAG peer to the secondary MLAG peer,
the ports are made members of the secondary MLAG peer switch's
spanning tree and spanning tree reconvergence may occur.. The forwarding
database and ARP cache are flushed and relearned.
MLAG (VPC) status only shows correctly on the primary MLAG peer and
does not show correctly on the secondary MLAG peer. Status is not
forwarded from the primary MLAG peer to the secondary MLAG peer.
If it is desired to run a redundant link between the MLAG peers, Multiple
Spanning Tree must be used, a separate VLAN must be configured for the
redundant link which cannot be configured on the peer link, and the
VLAN must be assigned to a unique MST instance not used by any MLAG
VLAN.
The Dell EMC Networking MLAG solution is not peer-compatible with other
vendor's multichassis LAG solutions. Dell EMC Networking N-Series
switches configured for MLAG cannot peer with another vendor switch.
IGMP/MLD snooping is not supported on MLAG-enabled switches. Disable
IGMP/MLD snooping before enabling MLAG.
MLAG interfaces and non-redundant ports cannot be members of the same
VLAN; i.e., a VLAN may contain MLAG interfaces or a VLAN may contain
non-redundant ports, but not both.
The Dell EMC Networking MLAG solution supports MSTP, RSTP, and
RSTP-PV spanning tree modes. Spanning tree may also be disabled on the
MLAG peers, although this may lead to a network loop. If MSTP is
configured, the MSTP domain MUST be named or the peer-link will remain
blocked.
Only two switches are supported as MLAG peers. These switches may not be
stacked with other switches.
The MLAG peer switches synchronize the state of spanning tree, the Layer-2
forwarding cache, and other protocols to support reduced convergence times
during MLAG link and MLAG switch failures. The synchronized state is only
available on the MLAG primary switch. Table 28-1 indicates which switch
features synchronize their state across the MLAG peers.
An N/A entry indicates that state synchronization is not required (usually
for a link local protocol) and the feature can be configured on an MLAG
VLAN or MLAG-associated links. In some cases, it may be necessary to
configure an N/A feature identically on the MLAG peer switches for it to