Overview

TRILL is a packet encapsulation standard specifically designed to meet the requirements of the data center (DC). It is similar to Service Provider Bridging (SPB) and Virtual Private LAN Service (VPLS), but is different in few key areas. Like MPLS, TRILL is considered a Layer 2½ protocol. From the end station device perspective, the network looks like a large, flat Layer 2 network. Within the network, bridge traffic is transported across the network using Layer 3 route forwarding techniques. Similar to SPB and VPLS, the TRILL packet payload includes the entire Ethernet packet starting with the destination MAC address (DA) field in the Ethernet header, through the Ethernet PDU (but does not include the FCS). TRILL also requires edge TRILL networking devices, hereto referred to as RBridges, to learn both local MAC address port/VLAN bindings, and remote network MAC address TRILL link/VLAN bindings associated with egress RBridges.

Note

Availability of TRILL is controlled through the purchase of the TRILL Feature Pack License.

Supported Platforms

TRILL is supported on the Extreme Networks BlackDiamond-X series, Summit X670 and X770 series switches. In a Summit Stack, all the switches must be Summit X670s or X770s. If one of the stack members is not a Summit X670 or X770, TRILL is not supported on the stack.

Note

TRILL is not supported on Summit x450-G2, X460-G2 or X670-G2.

Support Interfaces

TRILL is supported on all Ethernet interfaces for the supported platforms. TRILL can be enabled on any VLAN and Access VLANs may be configured for all or a portion of the 4K VLAN ID space from 1 through 4094 (0xFFE). Network TRILL interfaces are sometimes referred to as tunnel interfaces, though TRILL does not create tunnels based on the accepted networking definition of a tunnel.

TRILL does not provide point-to-point connections; traffic is free to take multiple paths based on the calculated path cost. For known unicast traffic, TRILL does provide a single ingress and single egress interface into and out of a non-native 802.3 Ethernet network. For this reason, you may see references to TRILL tunnels. In this context, the meaning only implies that a TRILL packet is carrying a native Ethernet packet from an ingress point to an egress point in the TRILL network. The path the packet takes is based on traditional routing topology algorithms.

The TRILL protocol treats each port in a VLAN as a distinctly separate interface (except when the ports are aggregated as an aggregation group). Thus, there could be multiple RBridges connected via point-to-point links to a single RBridge on VLAN 1. Each port to which another RBridge is connected is considered an adjacency on a non-shared link. This is an important distinction between TRILL and other routing protocols that use the IP interface to differentiate interfaces. An IP interface may have multiple ports that are members of a VLAN, and thus an IP interface. Since TRILL does not use IP addresses, the TRILL topology is port based and the VLAN tag is merely used to provide backwards compatibility so that standard 802.1Q bridges can co-exist with RBridges.

Published March 2020prev | next

Email this topic

Print this page Print this page

Leave feedback Feedback