Cisco 关于IP SLA及与EEM联动的探讨

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爱学习的IT民工 2014-04-02 11:51:32 博主文章分类：cisco

文章标签 Cisco 监控接口测量 frequency 文章分类 网络安全

SLA简介

SLA (Service-Level Agreement)简单的理解，就是测量一些网络性能参数，在超过一些门限值时，结合track或者EEM它可以触发一些操作。例如：
1. 监控下一跳的可达性，如果不可达了, 则让某一静态路由失效
2. 监控领居的接口地址，如果连续三次不可达, 则将端口shutdown

SLA 应用实例

如果客户的线路质量不好，又无法改善时，我们需要一种方法来：当线路质量达到一定阀值时，直接reset端口，用重置链路来改善。
那么我们如何达到这种需求呢，这时SLA就登场了，那么如何部署SLA呢？

分析第一种方法

ip sla 2 icmp-echo 1.1.1.2 timeout 3000 frequency 10<---频率设置为10S发一次ip sla schedule 2 life forever start-time now<---设置SLA的启动时间为马上，有效期为永远! Track 1 rtr 2<---配置track, trace有up和down两种状态! event manager session cli username "username" event manager applet test_track_1<---EEM 配置event track 1 state down<---如果track 1的状态是down的, 则执行下面的操作action 1.0 cli command "enable" action 2.0 cli command "conf t" action 3.0 cli command "int g4/3" action 3.1 cli command "shut" action 3.2 cli command "no shut" action 4.0 cli command "end"

根据以上配置，如果设备会每10秒发送一个PING包, 当超时时，track 1会变为down的状态，进而触发对端口的shut/no shut，这样达到最终的目的了么？在实际网络中，偶尔丢一个包是正常的、不可避免的，与此同时，端口是正常工作的。但是，根据上面的配置，端口依然会被reset，导致业务受到影响。

为了避免这一类不必要的业务影响，我们需要对此配置进行优化，让track 1在发生真正的网络故障时才down。
最常用的判断网络故障的标准是连续的超时！
因此加入以下命令（只说明增加的命令，另外修改的命令用红色标出）：

ip sla 4 icmp-echo 1.1.1.2 timeout 1000 frequency 10 ip sla schedule 4 life 5 start-time pending<---并不是马上启动，有效期也只有5秒! ip sla reaction-configuration 2 react timeout threshold-type consecutive 3 action-type trapandtrigger<---当发生连续3次timeout时，trigger另一个SLA，并发SNMP Trapip sla reaction-trigger 2 4<---SLA 2连续三次timeout就要trigger SLA 4! track 1rtr 4<---track SLA 4，而不是SLA 2，为什么？

如果配置track 1 rtr 2，则每次SLA 2超时时，track 1都会down，每down一次EEM都会reset端口，这样功能还是和之前一样不合理。所以，需要配置track 1 rtr 4，因为SLA 4是pending的，它在SLA 2连续三次超时时才被触发（10*3 + 5 =35S）

OK，那么问题解决了么？

经过测试，确实可以规避原丢一个包就启动EEM的问题。
但有个问题，因为要新增一个sla，如777，且其状态为pending，即只有在17丢三个包的情况下才启动777。

有如下两种情况：

1、线路已经开通时，这时配置如上命令时，因17无法连续丢3个包，导致777始终不能启动，导致track17的状态始终为down，最终导致不管丢多少包都不能启动EEM。（想想为什么？）

规避措施：配置完如上命令时需要shut上端或下端端口30s（因每10s探测一次），这时777才能启动，然后再做no shut操作，track17状态才能变为up，才能在专线中断的情况下正常启动EEM。所以在已经开通的线路配置如上命令时都要中断主用线路最少30s。

2、线路尚未开通时，这时需要在配置完如上命令最少30s才能开通此MSTP线路，否则同样会有如上问题。

Config：

ip sla monitor 17 type echo protocol ipIcmpEcho 12.1.1.2 timeout 3000 frequency 10 ! ip sla monitor reaction-configuration 17 react timeout threshold-type consecutive 3 action-type trapAndTrigger ip sla monitor reaction-trigger 17 777 ip sla monitor schedule 17 life forever start-time now ! ip sla monitor 777 type echo protocol ipIcmpEcho 12.1.1.2 timeout 1000 frequency 10 ! ip sla monitor schedule 777 life 5 start-time pending track 17 rtr 777 ! event manager session cli username "username" event manager applet test_track_17 event track 17 state down action 1.0 cli command "enable" action 2.0 cli command "conf t" action 3.0 cli command "int s1/0" action 3.1 cli command "shut" action 3.2 cli command "no shut" action 4.0 cli command "end" ! R1#sh debugging Track debugging is on Embedded Event Manager: Debug EEM action cli debugging is on IP SLA Monitor: TRACE debugging for all operations is on

Debug Information：

1. 初始配置后是down的状态：

R1(config)#track 17 rtr 777 *Feb 25 10:15:06.979: Track: 17 Adding rtr object *Feb 25 10:15:06.979: Track: Initialise *Feb 25 10:15:06.983: Track: 17 New rtr 777,state Down*Feb 25 10:15:06.987: Track: Starting process R1#sh track Track 17 Response Time Reporter 777 state State is Down 1 change, last change 00:01:19 Latest operation return code:UnknownTracked by: applet test_track_17

2. shutdown本断或对断端口，激活777，使track 17成为down

*Feb 25 10:16:25.107: IP SLA Monitor(777) Scheduler: Starting an operation *Feb 25 10:16:25.107: IP SLA Monitor(777) echo operation: Sending an echo operation *Feb 25 10:16:26.107: IP SLA Monitor(777) echo operation: Timeout *Feb 25 10:16:26.107: IP SLA Monitor(777) Scheduler: Updating result *Feb 25 10:16:26.777: IP SLA Monitor(777) Scheduler: Ageout R1#sh track Track 17 Response Time Reporter 777 state State is Down 1 change, last change 00:01:55 Latest operation return code:TimeoutTracked by: applet test_track_17

3. no shut端口，再次激活777，使其成为up

*Feb 25 10:17:42.159: IP SLA Monitor(777) Scheduler: Starting an operation *Feb 25 10:17:42.159: IP SLA Monitor(777) echo operation: Sending an echo operation *Feb 25 10:17:42.171: IP SLA Monitor(777) echo operation: RTT=12 *Feb 25 10:17:42.175: IP SLA Monitor(777) Scheduler: Updating result *Feb 25 10:17:42.175: IP SLA Monitor(777) Scheduler: Ageout *Feb 25 10:17:46.983: Track: 17 Change #2 rtr 777, state Down->Up R1#sh track Track 17 Response Time Reporter 777 state State is Up 2 changes, last change 00:09:16 Latest operation return code:OKLatest RTT (millisecs) 12 Tracked by: applet test_track_17

4. shutdown本端端口，测试是否可以达到效果
注意：下面的时间戳跟上面的不是连续的，是经过两次测试得到的

R1#config ter Enter configuration commands, one per line. End with CNTL/Z. R1(config)#int s1/0 R1(config-if)# R1(config-if)#shutdown R1(config-if)#end R1# *Feb 25 09:47:27.911: %LINK-5-CHANGED: Interface Serial1/0, changed state to administratively down *Feb 25 09:47:27.915: %ENTITY_ALARM-6-INFO: ASSERT INFO Se1/0 Physical Port Administrative State Down *Feb 25 09:47:28.911: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to down *Feb 25 09:47:31.775: IP SLA Monitor(17) Scheduler: Starting an operation *Feb 25 09:47:31.775: IP SLA Monitor(17) echo operation: Sending an echo operation *Feb 25 09:47:34.779: IP SLA Monitor(17) echo operation: Timeout *Feb 25 09:47:34.779: IP SLA Monitor(17) Scheduler: Updating result *Feb 25 09:47:41.775: IP SLA Monitor(17) Scheduler: Starting an operation *Feb 25 09:47:41.779: IP SLA Monitor(17) echo operation: Sending an echo operation *Feb 25 09:47:44.779: IP SLA Monitor(17) echo operation: Timeout *Feb 25 09:47:44.779: IP SLA Monitor(17) Scheduler: Updating result *Feb 25 09:47:51.775: IP SLA Monitor(17) Scheduler: Starting an operation *Feb 25 09:47:51.775: IP SLA Monitor(17) echo operation: Sending an echo operation *Feb 25 09:47:54.779: IP SLA Monitor(17) echo operation: Timeout *Feb 25 09:47:54.779: IP SLA Monitor(17) Scheduler: Updating result *Feb 25 09:47:54.827: IP SLA Monitor(777) Scheduler: Starting an operation *Feb 25 09:47:54.827: IP SLA Monitor(777) echo operation: Sending an echo operation *Feb 25 09:47:55.831: IP SLA Monitor(777) echo operation: Timeout *Feb 25 09:47:55.831: IP SLA Monitor(777) Scheduler: Updating result *Feb 25 09:47:55.835: IP SLA Monitor(777) Scheduler: Ageout *Feb 25 09:47:56.231: Track: 17 Change #5 rtr 777, state Up->Down *Feb 25 09:47:56.251: fh_schedule_callback: EEM callback policy EEM Policy Director has been scheduled to run *Feb 25 09:47:56.275: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : CTL : cli_open called. *Feb 25 09:47:56.291: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : *Feb 25 09:47:56.291: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : R1> *Feb 25 09:47:56.295: %HA_EM-6-LOG: R1#test_track_17 : DEBUG(cli_lib) : : IN : >enable *Feb 25 09:47:56.311: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : *Feb 25 09:47:56.311: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : R1# *Feb 25 09:47:56.311: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : #conf t *Feb 25 09:47:56.327: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : *Feb 25 09:47:56.331: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : Enter configuration commands, one per line. End with CNTL/Z. *Feb 25 09:47:56.335: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : R1(config)# *Feb 25 09:47:56.339: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : #int s1/0 *Feb 25 09:47:56.355: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : *Feb 25 09:47:56.355: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : R1(config-if)# *Feb 25 09:47:56.355: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : #shut *Feb 25 09:47:56.371: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : *Feb 25 09:47:56.375: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : R1(config-if)# *Feb 25 09:47:56.379: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : #no shut *Feb 25 09:47:56.411: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : *Feb 25 09:47:56.411: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : R1(config-if)# *Feb 25 09:47:56.415: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : #end *Feb 25 09:47:56.435: %SYS-5-CONFIG_I: Configured from console by name on vty1 *Feb 25 09:47:56.447: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : *Feb 25 09:47:56.447: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : R1# *Feb 25 09:47:56.451: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : #exit *Feb 25 09:47:56.455: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : CTL : cli_close called. *Feb 25 09:47:58.387: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up *Feb 25 09:47:58.391: %ENTITY_ALARM-6-INFO: CLEAR INFO Se1/0 Physical Port Administrative State Down *Feb 25 09:47:59.399: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up R1#sh track R1#sh track 17 Track 17 Response Time Reporter 777 state State is Up 6 changes, last change 00:15:41 Latest operation return code:OKLatest RTT (millisecs) 3 Tracked by: applet test_track_17

如何才能规避这种问题？或者说如何顺利满足要求呢？
其实在track中有非常方便的方法实现客户的要求，如下所示。

Config：

ip sla monitor 17 type echo protocol ipIcmpEcho 12.1.1.2 timeout 3000 frequency 10 ip sla monitor schedule 17 life forever start-time now ! track 1 rtr 17delay down 30<---用这个可以很简单的实现客户的需求!event manager session cli username "username" event manager applet test_track_17 event track 1 state down action 1.0 cli command "enable" action 2.0 cli command "conf t" action 3.0 cli command "int s1/0" action 3.1 cli command "shut" action 3.2 cli command "no shut" action 4.0 cli command "end"

Debug information:

1. default config and no action

R1#debug ip sla monitor trace IP SLA Monitor TRACE debugging for all operations is on R1# R1# R1#debug track *Feb 25 11:06:04.091: IP SLA Monitor(17) Scheduler: Starting an operation *Feb 25 11:06:04.091: IP SLA Monitor(17) echo operation: Sending an echo operation *Feb 25 11:06:04.135: Track: 1 Adding rtr object *Feb 25 11:06:04.139: Track: Initialise *Feb 25 11:06:04.143: Track:1 New rtr 17, state Down*Feb 25 11:06:04.147: Track: Starting process *Feb 25 11:06:04.155:IP SLA Monitor(17) echo operation: RTT=59*Feb 25 11:06:04.159:IP SLA Monitor(17) Scheduler: Updating result*Feb 25 11:06:09.143:Track: 1 Change #2 rtr 17, state Down->UpR1(config-applet)# R1(config-applet)# R1(config-applet)# R1(config-applet)# R1(config-applet)# *Feb 25 11:06:14.091: IP SLA Monitor(17) Scheduler: Starting an operation *Feb 25 11:06:14.091: IP SLA Monitor(17) echo operation: Sending an echo operation *Feb 25 11:06:14.159: IP SLA Monitor(17) echo operation: RTT=63 *Feb 25 11:06:14.163: IP SLA Monitor(17) Scheduler: Updating result *Feb 25 11:06:32.743: Track: 1 Start tracking by - 166397635de R1#sh track Track 1 Response Time Reporter 17 state State is Up 2 changes, last change 00:08:33 Delay down 30 secs Latest operation return code:OKLatest RTT (millisecs) 44 Tracked by: applet test_track_17

2. the link down and not recovery in 30
注意：由于上面设备出了点问题，现在换成别的设备，配置基本一样，只不过ip sla monitor 被 ip sla取代了。

C7304_CE2#config ter Enter configuration commands, one per line. End with CNTL/Z. C7304_CE2(config)#int g0/0 C7304_CE2(config-if)#shutC7304_CE2(config-if)#end C7304_CE2# C7304_CE2# C7304_CE2# 02:44:06: %SYS-5-CONFIG_I: Configured from console by console 02:44:08: %LINK-5-CHANGED: Interface GigabitEthernet0/0, changed state to administratively down 02:44:09: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to down 02:44:09: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:44:09: IP SLAs (17) Scheduler: Starting an operation 02:44:09: IP SLAs (17) echo operation: Sending an echo operation 02:44:12: IP SLAs (17) echo operation: Timeout 02:44:12: IP SLAs (17) Scheduler: Updating result02:44:15: Track: 1 Down change delayed for 30 secs02:44:19: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:44:19: IP SLAs (17) Scheduler: Starting an operation 02:44:19: IP SLAs (17) echo operation: Sending an echo operation 02:44:22: IP SLAs (17) echo operation: Timeout 02:44:22: IP SLAs (17) Scheduler: Updating result 02:44:29: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:44:29: IP SLAs (17) Scheduler: Starting an operation 02:44:29: IP SLAs (17) echo operation: Sending an echo operation 02:44:32: IP SLAs (17) echo operation: Timeout 02:44:32: IP SLAs (17) Scheduler: Updating result 02:44:39: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:44:39: IP SLAs (17) Scheduler: Starting an operation 02:44:39: IP SLAs (17) echo operation: Sending an echo operation 02:44:42: IP SLAs (17) echo operation: Timeout 02:44:42: IP SLAs (17) Scheduler: Updating result 02:44:45: Track: 1 Down change delay expired02:44:45: Track: 1 Change #4 rtr 17, state Up->Down02:44:45: %TRACKING-5-STATE: 1 rtr 17 state Up->Down02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : CTL : cli_open called.02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : C7304_CE2> 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : C7304_CE2>enable 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : C7304_CE2# 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : C7304_CE2#conf t 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : Enter configuration commands, one per line. End with CNTL/Z. 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : C7304_CE2(config)# 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : C7304_CE2(config)#int g0/0 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : C7304_CE2(config-if)# 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : C7304_CE2(config-if)#shut 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : C7304_CE2(config-if)# 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : C7304_CE2(config-if)#no shut 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : C7304_CE2(config-if)# 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : IN : C7304_CE2(config-if)#end 02:44:45: %SYS-5-CONFIG_I: Configured from console by name on vty0 (EEM:test_track_17) 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : OUT : C7304_CE2# 02:44:45: %HA_EM-6-LOG: test_track_17 : DEBUG(cli_lib) : : CTL : cli_close called. 02:44:47: %LINK-3-UPDOWN: Interface GigabitEthernet0/0, changed state to up 02:44:48: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up 02:44:49: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:44:49: IP SLAs (17) Scheduler: Starting an operation 02:44:49: IP SLAs (17) echo operation: Sending an echo operation 02:44:49: IP SLAs (17) echo operation: RTT=1 02:44:49: IP SLAs (17) Scheduler: Updating result02:44:50: Track: 1 Change #5 rtr 17, state Down->Up02:44:50: %TRACKING-5-STATE: 1 rtr 17 state Down->Up C7304_CE2# C7304_CE2# C7304_CE2#un all 02:44:59: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:44:59: IP SLAs (17) Scheduler: Starting an operation 02:44:59: IP SLAs (17) echo operation: Sending an echo operation 02:44:59: IP SLAs (17) echo operation: RTT=1 02:44:59: IP SLAs (17) Scheduler: Updating result All possible debugging has been turned off C7304_CE2# C7304_CE2#sh track Track 1 Response Time Reporter 17 state State is Up 5 changes, last change 00:00:14 Delay down 30 secs Latest operation return code:OKLatest RTT (millisecs) 1 Tracked by: EEM applet test_track_17

3. the link down, but recovery in 30s.

C7304_CE2#config ter Enter configuration commands, one per line. End with CNTL/Z. C7304_CE2(config)#int g0/0 C7304_CE2(config-if)# C7304_CE2(config-if)# 02:51:49: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:51:49: IP SLAs (17) Scheduler: Starting an operation 02:51:49: IP SLAs (17) echo operation: Sending an echo operation 02:51:49: IP SLAs (17) echo operation: RTT=1 02:51:49: IP SLAs (17) Scheduler: Updating result C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)#shutC7304_CE2(config-if)# C7304_CE2(config-if)# 02:51:58: %LINK-5-CHANGED: Interface GigabitEthernet0/0, changed state to administratively down 02:51:59: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to down 02:51:59: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:51:59: IP SLAs (17) Scheduler: Starting an operation 02:51:59: IP SLAs (17) echo operation: Sending an echo operation02:52:02: IP SLAs (17) echo operation: Timeout02:52:02: IP SLAs (17) Scheduler: Updating result02:52:05: Track: 1 Down change delayed for 30 secsC7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)#do sh track Track 1 Response Time Reporter 17 stateState is Up, delayed Down (24 secs remaining)7 changes, last change 00:00:30 Delay down 30 secs Latest operation return code: OK Latest RTT (millisecs) 1 Tracked by: EEM applet test_track_17 C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)# 02:52:09: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:52:09: IP SLAs (17) Scheduler: Starting an operation 02:52:09: IP SLAs (17) echo operation: Sending an echo operation 02:52:12: IP SLAs (17) echo operation: Timeout 02:52:12: IP SLAs (17) Scheduler: Updating result C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)#no shutC7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)#do sh track Track 1 Response Time Reporter 17 stateState is Up, delayed Down (15 secs remaining)7 changes, last change 00:00:39 Delay down 30 secs Latest operation return code: OK Latest RTT (millisecs) 1 Tracked by: EEM applet test_track_17 C7304_CE2(config-if)# 02:52:18: %LINK-3-UPDOWN: Interface GigabitEthernet0/0, changed state to up 02:52:19: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:52:19: IP SLAs (17) Scheduler: Starting an operation 02:52:19: IP SLAs (17) echo operation: Sending an echo operation 02:52:19: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up 02:52:22: IP SLAs (17) echo operation: Timeout 02:52:22: IP SLAs (17) Scheduler: Updating result C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)#do sh track Track 1 Response Time Reporter 17 stateState is Up, delayed Down (6 secs remaining)7 changes, last change 00:00:48 Delay down 30 secs Latest operation return code: OK Latest RTT (millisecs) 1 Tracked by: EEM applet test_track_17 C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)#do sh track Track 1 Response Time Reporter 17 stateState is Up7 changes, last change 00:00:50 Delay down 30 secs Latest operation return code: OK Latest RTT (millisecs) 1 Tracked by: EEM applet test_track_17 C7304_CE2(config-if)# 02:52:29: IP SLAs (17) Scheduler: saaSchedulerEventWakeup 02:52:29: IP SLAs (17) Scheduler: Starting an operation 02:52:29: IP SLAs (17) echo operation: Sending an echo operation 02:52:29: IP SLAs (17) echo operation: RTT=1 02:52:29: IP SLAs (17) Scheduler: Updating result02:52:30: Track: 1 Down change delay cancelledC7304_CE2(config-if)# C7304_CE2(config-if)#do sh track Track 1 Response Time Reporter 17 state State is Up 7 changes, last change 00:00:53 Delay down 30 secs Latest operation return code: OK Latest RTT (millisecs) 1 Tracked by: EEM applet test_track_17 C7304_CE2(config-if)# C7304_CE2(config-if)# C7304_CE2(config-if)#end C7304_CE2#un all All possible debugging has been turned off C7304_CE2#

OK，问题解决了，其实SLA与EEM能做很多事，举两个例子：
1. 如果在2层网络中使用浮动静态路由做backup，可能造成路由无法切换
7206-1（L3）—-（L2）3500（L2）—-（L2）3500（L2）—-（L3）7206-2

在7206之间存在两条线路，所以指两个静态到7206-2
这时有一个是浮动的，两个路由的下一跳都是7206-2的三层接口地址
如果7206-2出现问题，7206-1自动切换到浮动静态上
但实际上是不行的，主要原因就是7206-1和7206-2在一个网段中，所以只要7206-1的端口不down，那么浮动静态永远都不能激活。
此时只能用SLA的icmp echo来达成目的：

track 22 rtr 11 ip route 0.0.0.0 0.0.0.0 1.1.1.1 track 22 ip sla 11 icmp-echo 1.1.1.1 timeout 1000 frequency 5 ip sla schedule 11 life forever start-time now

2.定时采集信息
如果客户想在cpu利用率超过70%时，报出一些自定义的信息，或30秒采集某个端口的信息，这是就需要EEM出马了，用它可以简单实现客户的需求，在此配置就忽略了。