某局点在使用IS-IS路由协议后,网络管理员在设备互联接口上错误的调
用了包过滤,并在全局将包过滤的默认规则修改为拒绝后整个内网全部中断。
设备配置:
RTA配置:
packet-filter default deny
#
isis 1
network-entity 20.0000.0000.0001.00
#
interface LoopBack0
ip address 7.7.7.7 255.255.255.255
isis enable 1
#
interface GigabitEthernet0/0
port link-mode route
ip address 192.168.0.1 255.255.255.0
isis enable 1
#
interface GigabitEthernet0/2
port link-mode route
ip address 2.2.2.1 255.255.255.0
isis enable 1
isis bfd enable
packet-filter 3000 inbound
RTB配置:
isis 1
network-entity 20.0000.0000.0002.00
#
interface LoopBack0
ip address 9.9.9.9 255.255.255.255
isis enable 1
#
interface GigabitEthernet0/1
port link-mode route
ip address 1.1.1.1 255.255.255.0
isis enable 1
#
interface GigabitEthernet0/2
port link-mode route
ip address 2.2.2.2 255.255.255.0
isis enable 1
isis bfd enable
RTC配置:
isis 1
network-entity 20.0000.0000.0003.00
#
interface GigabitEthernet0/0
port link-mode route
ip address 192.168.0.2 255.255.255.0
isis enable 1
#
interface GigabitEthernet0/1
port link-mode route
ip address 1.1.1.2 255.255.255.0
isis enable 1
理论上RTA的0/2接口如果发生故障,那么路由会切换至RTC。但是现场路由却没有切换?
当在RTA执行“undo packet-filter default deny”时发现问题。
<H3C>%Mar 10 12:28:49:218 2018 H3C BFD/5/BFD_CHANGE_FSM: Sess[2.2.2.2/2.2.2.1, LD/RD:2049/2049, Interface:GE0/2, SessType:Ctrl, LinkType:INET], Ver:1, Sta: UP->DOWN, Diag: 3 (Neighbor Signaled Session Down) \\此时BFD会话已经检测失败
%Mar 10 12:28:49:220 2018 H3C ISIS/5/ISIS_NBR_CHG: IS-IS 1, Level-1 adjacency 0000.0000.0001 (GigabitEthernet0/2), state changed to DOWN, Reason: BFD session down. \\随即IS-IS路由信息也down了
%Mar 10 12:28:49:223 2018 H3C BFD/5/BFD_CHANGE_SESS: Sess[2.2.2.2/2.2.2.1, LD/RD:2049/0, Interface:GE0/2, SessType:Ctrl, LinkType:INET], Ver:1, Sta: Deleted, Diag: 3 \\此时BFD位置在INET状态
%Mar 10 12:28:49:236 2018 H3C ISIS/5/ISIS_NBR_CHG: IS-IS 1, Level-1 adjacency 0000.0000.0001 (GigabitEthernet0/2), state changed to UP, Reason: 2way-pass. \\随即IS-IS路由又恢复了
所以即使数据层面无法通信,那么IS-IS协议状态也不会切换。
通过NQA探测传输链路的状态,通过联动EAA执行相关测试。策略目的之间出问题出问题接口的IS-IS接口优先级修改大,致使路由切换。NQA探测恢复后再定义EAA策略恢复改接口优先级。
具体配置:
nqa entry 1 1
type icmp-echo
destination ip 7.7.7.7
frequency 1000
probe timeout 100
reaction 1 checked-element probe-fail threshold-type consecutive 3 action-type trigger-only
#
nqa schedule 1 1 start-time now lifetime forever
#
track 1 nqa entry 1 1 reaction 1
#
rtm cli-policy 1
event track 1 state negative
action 0 cli sys
action 1 cli in g0/2
action 2 cli isis cost 40 level-2
user-role network-admin
测试:在RTA执行“packet-filter default deny”,在路由信息中看到路由已经发生了切换。
[H3C]%Mar 10 16:59:48:620 2018 H3C NQA/6/NQA_ENTRY_PROBE_RESULT: Reaction entry 1 of NQA entry admin-name 1 operation-tag 1: probe-fail.
%Mar 10 16:59:48:672 2018 H3C RTM/6/RTM_POLICY: CLI policy 1 is running successfully.