Spanned Vlans; Vlt Unicast Routing - Dell C9000 Series Networking Configuration Manual

Spanned VLANs

Any VLAN configured on both VLT peer nodes is referred to as a Spanned VLAN. The VLT Interconnect (VLTi)
port is automatically added as a member of the Spanned VLAN. As a result, any adjacent router connected to
at least one VLT node on a Spanned VLAN subnet is directly reachable from both VLT peer nodes at the
routing level.

VLT Unicast Routing

VLT unicast routing locally routes packets destined for the L3 endpoint of the VLT peer. This method avoids
suboptimal routing.
In VLT unicast routing, peer-routing syncs the MAC addresses of both VLT peers and requires two local DA
entries in TCAM. In case a VLT node is down, a timer that allows you to configure the amount of time needed
for peer recovery provides resiliency. You can enable VLT unicast across multiple configurations using VLT
links. You can enable ECMP on VLT nodes using VLT unicast.
VLT unicast routing is supported on both IPv4 and IPv6. To enable VLT unicast routing, both VLT peers must
be in L3 mode. Static route and routing protocols such as RIP, OSPF, ISIS, and BGP are supported. However,
point-to-point configuration is not supported. To enable VLT unicast, VLAN configuration must be
symmetrical on both peers. You cannot configure the same VLAN as Layer 2 on one node and as Layer 3 on
the other node. Configuration mismatches are logged in the syslog and display in the show vlt mismatch
command output.
If you enable VLT unicast routing, the following actions occur:
• L3 routing is enabled on any new IP or IPv6 address configured for a VLAN interface that is up.
• L3 routing is enabled on any VLAN with an admin state of up.
NOTE: If the CAM is full, do not enable peer-routing.
NOTE: The peer-routing and peer-routing-timeout commands are supported on both IPv4 and
IPv6 to enable L3 VLT peer routing and configure the delay after which peer routing is disabled.
Configuring VLT Unicast
To enable and configure VLT unicast, follow these steps.
1 Enable VLT on a switch, then configure a VLT domain and enter VLT-domain configuration mode.
CONFIGURATION mode
vlt domain domain-id
2 Enable peer-routing.
VLT DOMAIN mode
peer-routing
3 Configure the peer-routing timeout.
VLT DOMAIN mode
Virtual Link Trunking (VLT) 1177