3com S7906E 설치 설명서

 

1-9 

Table 1-4 Description on the bits of the Flags field 

0 

Reserved, set to 0 

R 

z 

When set to 0, it indicates that this address is an IPv6 multicast address without 
an embedded RP address 

z 

When set to 1, it indicates that this address is an IPv6 multicast address with an 
embedded RP address (The P and T bits must also be set to 1) 

P 

z 

When set to 0, it indicates that this address is an IPv6 multicast address not 
based on a unicast prefix 

z 

When set to 1, it indicates that this address is an IPv6 multicast address based 
on a unicast prefix (the T bit must also be set to 1) 

T 

z 

When set to 0, it indicates that this address is an IPv6 multicast address 
permanently-assigned by IANA 

z 

When set to 1, it indicates that this address is a transient, or dynamically 
assigned IPv6 multicast address 

 

z 

Scope: 4 bits, indicating the scope of the IPv6 internetwork for which the multicast traffic is intended. 

Possible values of this field are given in 

Table 1-5 Values of the Scope field 

0, 3, F 

Reserved 

1 Interface-local 

scope 

2 Link-local 

scope 

4 Admin-local 

scope 

5 

Site-local scope  

6, 7, 9 through D 

Unassigned 

8 Organization-local 

scope 

E Global 

scope 

 

z 

Group ID: 112 bits, IPv6 multicast group identifier that uniquely identifies an IPv6 multicast group in 

the scope defined by the Scope field.  

When a unicast IP packet is transmitted over Ethernet, the destination MAC address is the MAC 

address of the receiver. When a multicast packet is transmitted over Ethernet, however, the destination 

address is a multicast MAC address because the packet is directed to a group formed by a number of 

receivers, rather than to one specific receiver.  

1)  IPv4 multicast MAC addresses 

As defined by IANA, the high-order 24 bits of an IPv4 multicast MAC address are 0x01005E, bit 25 is 0, 

and the low-order 23 bits are the low-order 23 bits of a multicast IPv4 address. The IPv4-to-MAC 

mapping relation is shown in 

.