IS-IS Hello 数据包包含 IPv4（和 IPv6 地址）。例如，查看此 IS-IS Hello 数据包中的“IPv4 接口”字段：

$ tcpdump -c1 -vvvr isis.pcap
reading from file isis.pcap, link-type EN10MB (Ethernet)
12:59:55.406559 IS-IS, length 81
        L2 Lan IIH, hlen: 27, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0)
        0x0000:  831b 0100 1001 0000
          source-id: 0101.2812.3087,  holding time: 9s, Flags: [Level 2 only]
          lan-id:    0101.2812.3087.02, Priority: 64, PDU length: 81
          0x0000:  0206 2128 1230 8700 0900 5140 0101 2812
          0x0010:  3087 02
            IS Neighbor(s) TLV #6, length: 12
              SNPA: dead.beef.6905
              SNPA: dead.beef.6906
              0x0000:  dead beef 6905 dead beef 6906
            Protocols supported TLV #129, length: 2
              NLPID(s): IPv4 (0xcc), IPv6 (0x8e)
              0x0000:  cc8e
            IPv4 Interface address(es) TLV #132, length: 4
              IPv4 interface address: 10.128.123.87
              0x0000:  3e80 7b57
            Area address(es) TLV #1, length: 4
              Area address (length: 3): 49.0233
              0x0000:  0349 0233
            Restart Signaling TLV #211, length: 3
              Flags [none], Remaining holding time 0s
              0x0000:  0000 00
            Authentication TLV #10, length: 17
              HMAC-MD5 password: 67cb4d674c12c0df8bb1b1ad06788c46 (unchecked)
              0x0000:  3600 0000 0000 0000 0000 0000 0000 0000
              0x0010:  00
$ 

此外，Cisco 和 Juniper 路由器都在show isis adjacency detail/sh isis neighbors输出中显示相邻路由器 IPv4/IPv6 地址。我是否正确，这个 IPv4/IPv6 地址总是属于发送 IS-IS PDU 的接口？这是在某些标准中指定的吗？为什么 IS-IS Hello 数据包中包含接口 IPv4/IPv6 地址？