VSC7440 datasheet(155/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

138

Figure 31 •

Multicast Routing Table Overview

3.19.2.3 Ingress Router Leg Lookup

The VID used to determine the ingress router leg is the classified VID. The classified VID can be

deducted based on a variety of parameters, such as VLAN tag or ingress port. For more information, see

VLAN Classification, page 110.

A total of 32 router legs are supported. Each router leg can be used for both IPv4 and IPv6 unicast and

multicast routing. A maximum of one router leg per VLAN is supported.

When processing incoming frames, the classified VID is used to index the VLAN table. The RLEG_ENA

parameter determines if the VLAN is enabled for routing of packets, and if so, the VMID is used to index

the VMID table. The flow is depicted in the following illustration.

VCAP

L3MC

Table

VLAN

Table

MSTP

Table

VMID

Table

IP Multicast Routing Decision

VMID

Table

VLAN

Table

MSTP

Table

VMID

Egress VMID

RLEG_EVID

MSTP_PTR

Classified VID

Second pass:

L3MC_PTR

from first pass

L2 Forwarding Decision

for Egress VLAN

L2 Forwarding Decision

for Ingress VLAN

First pass: (DIP,SIP)

VLAN_MSTP_PTR

First pass:

L3MC-PTR

Egress router leg/

egress VLAN

Ingress VLAN/

Ingress router leg

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