Administrator Guide

7. Congure symmetrical Layer 2 and Layer 3 congurations on both VLT peers for any spanned VLAN.
VLT Unicast Routing
VLT unicast locally routes packets destined for the L3 endpoint of the VLT peer.
This method avoids sub-optimal 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, resiliency is provided by a timer that allows you to congure the amount of time needed for
peer recovery.
VLT unicast also assists in conict resolution by updating the routing table when a path for an existing multicast route has been
changed. You can enable VLT unicast and multicast routing across multiple congurations using VLT links. ECMP can be enabled on
VLT nodes using VLT unicast; however, ECMP is not compatible on VLT nodes using VLT multicast. You must use a single VLAN.
VLT unicast is supported on both IPV6 / IPv4 . To enable VLT unicast, 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 conguration is not supported. To enable VLT
unicast, VLAN conguration must be symmetrical on both peers. The same VLAN cannot be congured as Layer 2 on one node and
as Layer 3 on the other node. Conguration mismatches are logged in the syslog and displayed in the output of the show vlt
inconsistency command.
When you enable VLT unicast, VLAN wildcarding is enabled to support up to 4094 VLANs. If you enable VLT unicast, the following
actions occur:
• L3 routing is enabled on any new IP address / IPV6 address congured for a VLAN interface that is up.
• L3 routing is enabled on any VLAN with an admin state of up.
• For PVLAN, if the IP address is congured for the primary VLAN, L3 routing is enabled.
NOTE: If the CAM is full, do not enable peer-routing.
NOTE: The peer routing and peer-routing-timeout is applicable for both IPv6/ IPv4.
Conguring VLT Unicast
To enable and congure VLT unicast, follow these steps.
1. Enable VLT on a switch, then congure a VLT domain and enter VLT-domain conguration mode.
CONFIGURATION mode
vlt domain domain-id
2. Enable peer-routing.
VLT DOMAIN mode
peer-routing
3. Congure the peer-routing timeout.
VLT DOMAIN mode
peer-routing—timeout value
value: Specify a value (in seconds) from 1 to 65535.
Non-VLT ARP Sync
In the Dell Networking OS version 9.2(0.0), ARP entries (including ND entries) learned on other ports are synced with the VLT peer
to support station move scenarios.
Prior to Dell Networking OS version 9.2.(0.0), only ARP entries learned on VLT ports were synced between peers.
Additionally, ARP entries resulting from station movements from VLT to non-VLT ports or to dierent non-VLT ports are learned on
the non-VLT port and synced with the peer node. The peer node is updated to use the new non-VLT port.
836
Virtual Link Trunking (VLT)