46组播修改ttl实验

1、组播修改ttl实验r1是源,所有路由器运行ospf并互通,组播接口运行pim-dm协议,r4, r5模拟主机, 并加入组地址224.2.2.2现在ping组地址，收到r4和r5的replyrl#p 224.2.2.2type escape sequenee to abort.sending 1,100-byte icmp echos to 224.2.2.2, timeout is 2 seconds:reply to request 0 from 192.16835.5,176 msreply to request 0 from 192.168.34.4,176 ms在r3上查看pim接口的

2、详细信息，发现默认ttl=or3#sh ip pirn in terface sl/1 deseriall/1 is up, line protocol is upinternet address is 192.168.34.3/24multicast switching: fastmulticast packets in/out: 0/6multicast boundary: not setmulticast ttl threshold: 0pim: enabledpim version: 2, mode: densepim dr:0.0.0.0pim neighbor count: 0pi

3、m hello/query interval: 30 secondspim hello packets in/out: 0/13pim state-refresh processing: enabledpim state-refresh origination: disabledpim nbma mode: disabledpim atm multipoint signalling: disabledpim domain border: disabledmulticast tagswitching: disabledr3#sh ip pirn interface f0/0 defastethe

4、rneto/o is up, line protocol is upinternet address is 192.168.35.3/24multicast switching: fastmulticast packets in/out: 0/1multicast boundary: not setmulticast ttl threshold: 0pim: enabledpim version: 2, mode: densepim dr: 192.168.35.3 (this system)pim neighbor count: 0pim hello/query interval: 30 s

5、econdspim hello packets in/out: 0/23pim state-refresh processing: enabledpim state-refresh origination: disabledpim nbma mode: disabledpim atm multipoint signalling: disabledpim domain border: disabledmulticast tagswitching: disabled现在改变r3上两个接口的ttl |'1限，对于r4的ttl=5,对于r5的ttl=6r3(config)#int sl/1r3

6、(config-if)#ip multicast ttl-threshold 5r3(config-if)#int f0/0r3(config-if)#ip multicast ttl-threshold 6r1的ping信息，将ttl设为8发送，r4和r5都回复了 reply信息rl#pingprotocol ip:target ip address: 224.2.2.2repeat count 1: 5datagram size 100:timeout in seconds 2:extended commands n: yinterface all:time to live 255: 8t

7、ype of service 0:set df bit in ip header? no:validate reply data? no:data pattern oxabcd:loose, strict, record, timestamp, verbosenone:sweep range of sizes n:type escape sequenee to abortsending 5,100-byte icmp echos to 224.2.2.2, timeout is 2 seconds:reply to request 0 from 192.168.35.5,104 msreply

8、 to request 0 from 192.168.34.4,104 msreply to request 1 from 192.168.34.4,144 msreply to request 1 from 192.168.35.5,160 msreply to request 2 from 192.168.35.5, 92 msreply to request 2 from 192.16834.4,152 msreply to request 3 from 192.168.35.5,116 msreply to request 3 from 192.168.34.4,116 msreply

9、 to request 4 from 192.168.35.5, 76 msreply to request 4 from 192.168.34.4, 76 msr3 ± debug,经过r2 跳后，再进行rpf检测，ttl从8减到了 6r3(config-if)#no ip mroute-cacher3(config-if)#azr3#debug ip mpacket detailr3#*mar 23 14:32:26.239: ip(0): mac sa=*hdlc* (seriall/0)*mar 23 14:32:26.239: ip(0): ip tos=oxo, len=

10、100z id=79, ttl=6, prot=l*mar 23 14:32:26.243: ip(0): s=192.168.12.1 (seriall/0) d=224.2.2.2 (seriall/1) id=79, prot=l, len=100(100), mforward*mar 23 14:32:26.247: ip(0): s=192.168.12.1 (seriall/0) d=224.2.2.2 (fastetherneto/o) id=79z prot=l, len=100(100), mforward综上，数据包的ttl大于等于门限值则可以转发。r1的ping信息，将t

11、tl设为7发送，只有r4回复了 reply信息rl#pprotocol ip:target ip address: 224.2.2.2repeat count 1: 5datagram size 100:timeout in seconds 2:extended commands n: yinterface all:time to live 255: 7type of service 0:set df bit in ip header? no:validate reply data? no:data pattern oxabcd:loose, strict, record, timestamp

12、, verbosenone:sweep range of sizes n:type escape sequence to abort.sending 5,100-byte icmp echos to 224.2.2.2, timeout is 2 seconds:reply to request 0 from 192.168.34.4,152 msreply to request 1 from 192.168.34.4,116 msreply to request 2 from 192.168.34.4,116 msreply to request 3 from 192.168.34.4,172 msreply to request 4 from 192.168.34.4, 88 msr3#*mar 23 14:38:09.131: ip(0): mac sa=*hdlc* (seriall/0)*mar 23 14:38:09.131: ip(0): ip tos=0x0, len=100, id=80, ttl=5, prot=l*mar 23 14:38:09.135: ip(0): s=192.168.12.1 (seria