Behavior with VLAN Interfaces Configured

This section discusses the following:

n	Multiple Logical Interfaces

n	How an outbound packet is processed for a tagged tunnel

n	Delivering Inbound Packets to the LAN: VLAN Interfaces Configured

n	Cisco VLAN Example with Multiple Interfaces

Multiple Logical Interfaces

n	On the Configuration - Deployments page, you can add VLAN interfaces to the Silver Peak appliance by clicking +VLAN. Here are two separate excerpts from that page — one in Bridge mode (in-line) and one in Router mode (out-of-path).

Note If you try to configure something that’s incorrect or not supported, a message appears in a red banner at the bottom of the page, telling you what you need to do.

n	Any of these logical interfaces can be a tunnel endpoint.

•	If a tunnel endpoint has a VLAN tag, then outbound packets directed to that tunnel receive that VLAN tag.

•	If a tunnel endpoint has no tag, then outbound packets remain untagged after processing. This is the default behavior.

n	Once VLANs are configured on the appliance, tunnels built off of a VLAN interface are tagged using the VLAN ID associated with the VLAN interface — so all outgoing optimized traffic will have the L2 tag.

How an outbound packet is processed for a tagged tunnel

The following actions happen to every packet entering the appliance for optimization on its way to the WAN:

a	The appliance strips away the existing L2 header.

b	The appliance applies a new L2 header, designating the appliance as the Source MAC.

c	The encapsulated tunnel packet uses the tunnel endpoint’s VLAN ID to tag the outgoing packet.

Tagged outbound packet to tagged tunnel

Both the outbound LAN packet and the tunnel endpoint have a VLAN tag.

Delivering Inbound Packets to the LAN: VLAN Interfaces Configured

For packets arriving from the WAN, the LAN route table is what determines where a packet goes.

•	After discarding the arriving packet’s L2 and tunnel headers, the appliance does a LAN route table lookup, based solely on the Destination Host IP address.

•	Based on the destination’s subnet, the appliance determines which VLAN tag to use.

•	The appliance must have an interface configured for each such VLAN.

Cisco VLAN Example with Multiple Interfaces

The example below shows the configurations for the appliance and a Cisco router.

w	To install the Silver Peak on a VLAN trunk

1	Access the Configuration - Deployment page:

a	For the untagged native VLAN, enter an IP address in the WAN router’s native VLAN subnet.

b	Specify the Next Hop, and leave the VLAN field blank.

2	To add a VLAN interface, click +VLAN and complete the Appliance IP, Mask, VLAN, and Next Hop fields.

Note The VLAN IP must be a host IP and not a subnet IP address.

3	To verify that each Next-hop IP address is reachable, do the following:

a	Check Monitoring > Routes, for State = Reachable.

b	Check the Alarms page.

Please send comments or suggestions regarding user documentation to techpubs@silver-peak.com.