CiscoIPSLA可用于链接到两家ISP情况下,可以执行可达性测试,只有当ISP网络可达时,它才通告该路由,这样就可以避免因ISP不可达而丢失数据包。例如,下图中,ISP-1到Internet的连接出现故障,但连接到客户的接口正常,这时客户的数据流仍会发送给ISP-1,这些数据就会在ISP-1处丢失。
一、实验步骤
1.配置路由器
R1:
配置路由协议:
R1(config)#ip route 0.0.0.0 0.0.0.0 209.165.201.1 |
配置SLA:
R1(config)#ip sla 11 //定义一个LSA编号,范围是1~2147483647 R1(config-ip-sla)#icmp-echo 209.165.201.30 //定义操作类型为“icmp-echo”,用于连通性测试,指定目标地址 R1(config-ip-sla-echo)#fre R1(config-ip-sla-echo)#frequency 10 //定义SLA操作的频率,默认为60s R1(config-ip-sla-echo)#exit R1(config)#ip sla schedule 11 life forever start-time now //配置SLA的参数,”Life“默认为3600s,”forever“表示一直有效,”Ageout“定义停止信息采集后,在内存中保存的时间,默认是0,即一直保留。”start-time“定义开始采集的时间,”Now“表示立即采用,也可以使用”after“参数定义在多长时间后开始。 |
应用SLA:
R1(config)#track 1 rtr 11 reachability //定义跟踪对象,应该为track 1 ip sla 11 reachability,不知怎么不支持该配置,只能使用track 1 rtr 11 reachability ,12.4的IOS应该支持的,难道是模拟器的问题吗? R1(config-track)#delay down 10 up 1 //这个是?? R1(config)#ip route 0.0.0.0 0.0.0.0 209.165.201.1 2 track 1 //配置跟踪对象的默认路由,管理距离设置为2 对于通往ISP-2链路: track 2 ip sla 22 reachability delay down 10 up 1 exit ip route 0.0.0.0 0.0.0.0 209.165.202.129 3 track 2 //管理距离为3,此时,浮动静态路由会首选ISP-1 |
R2:配置路由协议:
R2(config)#router eigrp 1 R2(config-router)#network 209.165.200.224 0.0.0.3 R2(config-router)#network 209.165.201.0 0.0.0.31 R2(config-router)#no auto R2(config-router)#no auto-summary R2(config)#ip route 192.168.1.0 255.255.255.0 209.165.201.2 |
R3:
R3(config)#router eigrp 1 R3(config-router)#network 209.165.200.224 0.0.0.3 *Mar 1 00:19:26.903: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 209.165.200.225 (Serial3/1) is up: new adjacency R3(config-router)#network 209.165.202.128 0.0.0.31 R3(config-router)#no auto-summary *Mar 1 00:20:00.035: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 209.165.200.225 (Serial3/1) is resync: summary configured R3(config)#ip route 192.168.1.0 255.255.255.0 209.165.201.2 |
2.调试
查看SLA配置:
R1(config)#do sh ip sla config 11 IP SLAs, Infrastructure Engine-II. Entry number: 11 //IPSLA操作编号 Owner: //SNMP的拥有者 Tag: //用户指定的 IP SLA标识 Type of operation to perform: icmp-echo //IPSLA的操作类型 Target address/Source address: 209.165.201.30/0.0.0.0 //监控的目标地址和源地址 Operation timeout (milliseconds): 5000 //等待SLA操作的请求数据包的响应时间 Type Of Service parameters: 0x0 //服务类型参数 Vrf Name: Request size (ARR data portion): 28 //SLA操作的请求数据包的payload大小 Verify data: No //没有验证SLA响应数据 Schedule: Operation frequency (seconds): 10 (not considered if randomly scheduled) Next Scheduled Start Time: Start Time already passed Group Scheduled : FALSE Randomly Scheduled : FALSE Life (seconds): Forever Entry Ageout (seconds): never Recurring (Starting Everyday): FALSE //指的是每天在指定时间自动执行,并持续life指定的时间 Status of entry (SNMP RowStatus): Active Threshold (milliseconds): 5000 //计算对收集信息统计的门限值 Distribution Statistics: Number of statistic hours kept: 2 Number of statistic distribution buckets kept: 1 Statistic distribution interval (milliseconds): 20 //统计间隔 History Statistics: Number of history Lives kept: 0 Number of history Buckets kept: 15 History Filter Type: None Enhanced History: |
R1(config)#do sh ip sla statistics 11 Round Trip Time (RTT) for Index 11 Latest RTT: 28 milliseconds Latest operation start time: *01:07:28.251 UTC Fri Mar 1 2002 //最后一次探测时间 Latest operation return code: OK //最后操作返回的代码 Number of successes: 227 //探测成功的次数 Number of failures: 1 //探测失败的次数 Operation time to live: Forever |
查看track:
R1(config)#do sh track Track 1 Response Time Reporter 11 reachability Reachability is Up //可达性为up 1 change, last change 00:23:13 Delay up 1 sec, down 10 secs //up和down的延迟时间 Latest operation return code: OK Latest RTT (millisecs) 32 Tracked by: STATIC-IP-ROUTING 0 //在静态路由中使用 Track 2 Response Time Reporter 22 reachability Reachability is Down 1 change, last change 00:01:14 Latest operation return code: Timeout Tracked by: STATIC-IP-ROUTING 0 |
查看路由表:
Gateway of last resort is 209.165.201.1 to network 0.0.0.0 209.165.201.0/30 is subnetted, 1 subnets C 209.165.201.0 is directly connected, Serial3/0 209.165.202.0/30 is subnetted, 1 subnets C 209.165.202.128 is directly connected, Serial3/2 C 192.168.1.0/24 is directly connected, Loopback0 S* 0.0.0.0/0 [2/0] via 209.165.201.1 //采用ISP-1路由 |
down掉通往ISP-1的Server,即loopback 1:
R2(config)#int lo 1 R2(config-if)#shutdown R2(config-if)# *Mar 1 01:21:35.155: %LINK-5-CHANGED: Interface Loopback1, changed state to administratively down *Mar 1 01:21:36.155: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to down |
查看路由表:
Gateway of last resort is 209.165.201.1 to network 0.0.0.0 209.165.201.0/30 is subnetted, 1 subnets C 209.165.201.0 is directly connected, Serial3/0 209.165.202.0/30 is subnetted, 1 subnets C 209.165.202.128 is directly connected, Serial3/2 C 192.168.1.0/24 is directly connected, Loopback0 S* 0.0.0.0/0 [3/0] via 209.165.202.129 |
此时,R1采用了ISP-2。