Dell Force10 S4810P Configuration Manual page 1068

• The VLT interconnect is used for data traffic only when there is a link failure that requires the
VLTi to be used in order for data packets to reach their final destination.
• Unknown, multicast and broadcast traffic can be flooded across the VLT interconnect.
• MAC addresses for VLANs configured across VLT peer chassis are synchronized over the VLT
interconnect on an egress port such as a VLT LAG. MAC addresses are the same on both VLT
peer nodes.
• ARP entries configured across the VLTi are the same on both VLT peer nodes.
• If you shut down the port channel used in the VLT interconnect on a peer switch in a VLT domain
in which no backup link is configured, the switch's role is displayed in
output as Primary instead of Standalone.
• When you change the default VLAN ID on a VLT peer switch, the VLT interconnect may flap.
• In a VLT domain, the following software features are supported on VLTi: LLDP, flow control,
port monitoring, jumbo frames, DCB.
• When the VLTi link is enabled, the link between the VLT peer switches is established if the
following configured information is true on
Note: If the VLT system MAC address or VLT unit-id is configured on only one of the VLT peer switches,
the link between the VLT peer switches will be not be established. Each VLT peer switch must be
correctly configured to establish the link between the peers.
• If the link between the VLT peer switches is established, changing the VLT system MAC address
or the VLT unit-id will
However, removing the VLT system MAC address or the VLT unit-id may cause the VLT ports to
be disabled if the unit ID or system MAC address happens to be configured on only one VLT peer
at any time.
• If the link between VLT peer switches is established, any change to the VLT system MAC address
or unit-id will fail if the changes made create a mismatch by causing the VLT unit-ID to be the
same on both peers and/or the VLT system MAC address does not match on both peers.
• If you replace a VLT peer node, pre-configure the switch with the VLT system MAC address,
unit-id, and other VLT parameters before connecting it to the existing VLT peer switch using the
VLTi connection.
• If the size of the MTU for VLTi members is less than 1496 bytes, MAC addresses may not be
synced. Dell Force10 recommends retaining the default MTU allocation (1554 bytes) for VLTi
members.
• VLT Backup link:
• In the backup link between peer switches, heartbeat messages are exchanged between the two
chassis for health checks. The default time interval between heartbeat messages over the backup
link is 1 second. This interval is user-configurable; range: 1 to 5 seconds. DSCP marking on
heartbeat messages is CS6.
• In order that the chassis backup link does not share the same physical path as the interconnect
trunk, it is recommended that you use the management ports on the chassis and traverse an
out-of-band management network. The backup link can use user ports, but not the same ports as
used by the interconnect trunk.
1068
| Virtual Link Trunking (VLT)
— the VLT system MAC address matches.
— the VLT unit-id is not identical.
cause the link between the VLT peer switches to become disabled.
not
peer switches:
both
command
show vlt brief