为什么Cisco路由器在NDP RA中的地址在该范围内时会用NDP RA为前缀做广告？

Question

如果我写

interface Vlan1
 ... {ipv4 config} ...
 ipv6 address 2001:DB8:5432:101::/64 eui-64
 ipv6 address FDAA:DB8:5432:101::/64 eui-64
 ipv6 enable
 ipv6 nd prefix 2001:DB8:5432:101::/64
 ipv6 nd prefix FDAA:DB8:5432:101::/64
 ipv6 nd other-config-flag
 ipv6 nd ra interval 4
 ipv6 dhcp server DHCP6_POOL
!

然后我看到的NDP RAs看起来(tcpdump，连接到Vlan1的机器)

IP6 (class 0xe0, hlim 255, next-header ICMPv6 (58) payload length: 96) fe80::{router's eui-64} > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 96
hop limit 64, Flags [other stateful], pref medium, router lifetime 1800s, reachable time 0ms, retrans timer 0ms
  source link-address option (1), length 8 (1): {router's eui-48}
  mtu option (5), length 8 (1):  1500
  prefix info option (3), length 32 (4): 2001:db8:5432:101::/64, Flags [onlink, auto], valid time 2592000s, pref. time 604800s
  prefix info option (3), length 32 (4): fdaa:db8:5432:101::/64, Flags [onlink, auto], valid time 2592000s, pref. time 604800s

完全和预期的一样。广告中的前缀是用ipv6 nd prefix *::/64配置的，不多也不少。

但是，如果我在与ipv6 address的接口上配置了其他地址，但不要将这些前缀添加为ipv6 nd prefix，如下所示

interface Vlan1
 ... {ipv4 config} ...
 ipv6 address 2001:DB8:5432:101::/64 eui-64
 ipv6 address 2001:DB8:5432:102::/64 eui-64
 ipv6 address FDAA:DB8:5432:101::/64 eui-64
 ipv6 address FDAA:DB8:5432:102::/64 eui-64
 ipv6 enable
 ipv6 nd prefix 2001:DB8:5432:101::/64
 ipv6 nd prefix FDAA:DB8:5432:101::/64
 ipv6 nd other-config-flag
 ipv6 nd ra interval 4
 ipv6 dhcp server DHCP6_POOL
!

然后，我希望RAs只适用于用ipv6 nd prefix指定的前缀，但是我看到RAs包含所有四个前缀：

IP6 (class 0xe0, hlim 255, next-header ICMPv6 (58) payload length: 160) fe80::{router's eui-64} > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 160
hop limit 64, Flags [other stateful], pref medium, router lifetime 1800s, reachable time 0ms, retrans timer 0ms
  source link-address option (1), length 8 (1): {router's eui-48}
  mtu option (5), length 8 (1):  1500
  prefix info option (3), length 32 (4): 2001:db8:5432:101::/64, Flags [onlink, auto], valid time 2592000s, pref. time 604800s
  prefix info option (3), length 32 (4): 2001:db8:5432:102::/64, Flags [onlink, auto], valid time 2592000s, pref. time 604800s
  prefix info option (3), length 32 (4): fdaa:db8:5432:101::/64, Flags [onlink, auto], valid time 2592000s, pref. time 604800s
  prefix info option (3), length 32 (4): fdaa:db8:5432:101::/64, Flags [onlink, auto], valid time 2592000s, pref. time 604800s

我可以使用什么配置来为路由器提供Vlan1上的所有四个地址，但只为原来的两个地址做广告，这样动态设备只能在101个子网中自动配置，但是路由器仍然可以与102个子网中静态分配的地址对话？

Answer 1

ipv6 nd prefix default no-advertise

或列出不宣布的接口地址。

ipv6 nd prefix 2001:DB8:5432:102::/64 no-advertise
ipv6 nd prefix FDAA:DB8:5432:102::/64 no-advertise