VSC7440 datasheet(163/444 Pages) MICROSEMI

163 / 444 page

Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

146

Figure 36 •

IP Multicast Routing Example

A sender host with IPv4 address 1.1.1.3 is transmitting IPv4 multicast frames to the group address

230.1.1.1 and DMAC = 0x01005E010101. The frames must be L2 forwarded to receivers in VLAN 1 and

L3 forwarded to receivers in VLAN 2. For the latter, an entry for the (1.1.1.3, 230.1.1.1) pair is added to

the VCAP LPM.

3.19.2.5.1 Stage 1

•

Lookup of (SIP,G) = (1.1.1.3, 230.1.1.1) in VCAP LPM returns L3MC_IDX = 0 and a corresponding

entry in L3MC table. L3MC_IDX = 0 is inserted into the IFH.

•

The L3MC entry has RPF check enabled (RPF_ENA = 1). Because the frame has been received

through the specified router leg, L3 forwarding is allowed.

•

The L3MC entry specifies that frames are forwarded to router leg 1 and 2. Because the frame has

been received on router leg 1, only router leg 2 needs a routed copy. In other words, the number of

L3 frame copies required is set to 1.

•

If the frame’s TTL is <2, then the frame is not L3 forwarded.

•

Lookup of (DMAC, VID) = (0x01005E010101, 1) in the MAC table returns a destination set with port

8 and 9. Port 8 is source filtered due to normal L2 source port filtering, so the resulting destination

set consists only of port 9.

•

As a result of the first stage, the frame has been L2 forwarded to port 9 and a copy with

L3MC_IDX = 0 and L3 copies required = 1 has been forwarded to the VD0.

3.19.2.5.2 Stage 2

•

A frame is received once from VD0 with L3MC_IDX = 0 and L3MC_COPY_CNT = 1.

•

Lookup of L3MC_IDX = 0 in the L3MC table returns the same entry as used in stage 1. Because this

is the first routed copy, the new EVMID is 2, and through lookup in the VMID table, the

corresponding EVID is 2.

•

If Frame.IP.TTL < VMID.VMID_MC.RLEG_IP4_MC_TTL, the frame is not L3 forwarded.

•

The frame’s TTL is decremented.

•

Lookup of (DMAC, VID) = (0x01005E010101, 2) in the MAC table returns a destination set with port

10 and 11. Because this is a routed copy, no source port filtering is applied.

Sender

Receiver 1

Receiver 2

1.1.1.3

1.1.1.1

2.2.2.2

1.1.1.2

Receiver 3

2.2.2.3

2.2.2.1

VLAN 2

IP network 2.2.2.0/24

VLAN 1

IP network 1.1.1.0/24

n+4

Index

n+2

VCAP Entries

L3MC Table

Valid

CPU

EVMID_MASK

(Router leg bit mask)

128 bits

RPF_

VMID

0x6

RPF_CHK_

ENA

0xFF

230.1.1.1

2.2.2.2

SIP

230.1.1.1 1.1.1.3

230.1.1.1

l3mc_idx

VCAP

Actions

230.1.1.2 2.2.2.2

Index

1023

Router

leg 1

Router

leg 2

LPM VCAP

VSC7440 датащи(PDF) 163 Page - Microsemi Corporation

VSC7440 датащи(HTML) 163 Page - Microsemi Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL