H3C Technologies H3C S10500 Series Switches - Manual (Page 11)

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ENDC
An EVI neighbor discovery client works with an ENDS to learn neighbor information and triggers EVI link
setup between neighbors.
EVI IS-IS
EVI IS-IS establishes adjacencies and advertises MAC reachability information among edge devices at
different sites in an EVI network.
EVI IS-IS runs independently of the Layer 3 routing protocols on the transport network and sites.
DED
Designated edge devices (DEDs) include inter-site DEDs and site DED.
An inter-site DED is elected from between the edge devices on each EVI link to send CSNP packets for
LSDB synchronization.
A site DED is elected from among the redundant edge devices at a multihomed site to distribute extended
VLANs among them so the traffic of a VLAN always enters or leaves the site from the same edge device.
The current software version does not support multihoming. In this document, DEDs only refer to inter-site
DEDs.
Appointed edge forwarder
If an edge device is assigned by the site DED to forward and receive traffic for an extended VLAN, this
edge device is the appointed edge forwarder for the extended VLAN. This extended VLAN is an active
VLAN on the edge device.
Internal interface
Internal interfaces are site-facing Layer 2 interfaces that connect an edge device to switches or routers in
the site.
Working mechanism
An edge device uses the following process to set up an EVI network and forward traffic at Layer 2 to
remote sites:
1. Runs ENDP to discover EVI neighbors and set up EVI links between neighbors.
2. Runs EVI IS-IS to advertise MAC reachability information over EVI links in the EVI network.
3. Forwards traffic based on MAC reachability information that has been received from other sites.
This section describes this process in detail.
Neighbor discovery
An EVI network runs ENDP to discover all its edge devices and establishes adjacencies among the edge
devices in the following process:
1. ENDS is enabled on one edge device, and ENDC is enabled on all other edge devices.
2. The ENDCs register their IP addresses and other data with the ENDS.
3. The ENDS updates its ENDC database with received data and sends the updated database to
each ENDC.
4. After receiving the register reply, the ENDCs establish an EVI link with each other.
For high availability, you can configure up to two ENDSs for an EVI network.