VSC7440 datasheet(153/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

136

if (req.l3_sip_match == 0) {

csr.secur_sip_fail_sticky = 1;

}

3.19.2

IP Routing

The device supports routing of IPv4 and IPv6 unicast and multicast packets through the 32 router

interfaces, also known as “router legs”. Each router leg is attached to a VLAN.

The following illustration shows a configuration with three VLANs, each with an attached router leg for

routing IP packets between the VLANs. Port 11 is member of both VLAN 1 and VLAN 2.

When a packet is being routed from one VLAN (the ingress VLAN) to another VLAN (the egress VLAN),

the VID of the ingress VLAN is termed IVID, and the VID of the egress VLAN is termed the EVID.

Figure 29 •

Router Model

Within the device, a router leg is identified by a 5-bit VMID value. When a packet is being routed, it is

then received by the router entity using a router leg identified by an ingress VMID (or IVMID) and

transmitted on an egress router leg identified by an egress VMID (or EVMID).

IP routing, also known as L3 forwarding, is only supported in VLAN-aware mode.

3.19.2.1 Frame Types for IP Routing

In order for IP packets to be routed by the device, the following conditions must be met.

•

IPv4 packets must not contain options.

•

IPv6 packets must not contain hop-by-hop options.

•

Optionally packets with some illegal SIP and DIP addresses can be filtered. For more information,

see Illegal IPv4 Addresses, page 140 and Illegal IPv6 Addresses, page 140.

•

IPv4 header checksum must be correct.

3.19.2.2 Routing Table Overview

The following illustration provides an overview of the table lookups involved in IP unicast routing within

the L3 part of the analyzer.

The VCAP and ARP table lookups are performed in parallel with the VLAN/MSTP/VMID table lookups. If

the frame does not match a router leg, the result of VCAP and ARP table lookups are not used for

routing.

VLAN 2

VLAN 3

10 11

12 13 14 15 16 17 18 19

VLAN 1

Router Leg

Router

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