题目;AR29的loopback0无法访问AR33的loopback0。
一、故障根因判断
AR29的loopback0无法访问AR33的loopback0的根本原因是:AR29和AR33存在hello时间不一致,(Hello Int: 10, Hello Int: 15),并且区域类型不一致(Option: _E_,Option: _N_)。其中AR29被配置为普通区域类型,AR33被配置为了NSSA区域类型。
二、故障分析
2.1 故障重现:在AR29上,以自身的Loopback0接口的地址作为源地址去ping AR33的LoopBack0接口的地址,测试结果如下:
<AR29>ping -a 10.5.1.29 10.5.1.33
PING 10.5.1.33: 56 data bytes, press CTRL_C to break
Request time out
Request time out
Request time out
Request time out
Request time out --- 10.5.1.33 ping statistics ---
5 packet(s) transmitted
0 packet(s) received
100.00% packet loss
------------------------------------------------------------------------------------------------------------------------------ 由测试结果得知,故障确实存在,需要在AR29上检查路由表是否存在AR33的Loopback0接口地址的路由。
2.2 在AR29上使用display ip routing-table 命令检查是否存在AR33的Loopback0接口地址的路由,测试及输出结果如下所示:
<AR29>dis ip routing-table
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 11 Routes : 11 Destination/Mask Proto Pre Cost Flags NextHop Interface
10.5.1.29/32 Direct 0 0 D 127.0.0.1 LoopBack0
10.5.40.0/24 Direct 0 0 D 10.5.40.30 GigabitEthernet
0/0/1
10.5.40.30/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/1
10.5.40.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/1
10.5.128.0/24 Direct 0 0 D 10.5.128.30 GigabitEthernet
0/0/0
10.5.128.30/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/0
10.5.128.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/0
127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
------------------------------------------------------------------------------------------------------------------------------ 由以上输出可见,AR29并不存在到达AR33的Loopback0接口地址的路由。由于当前运行的是OSPF路由协议,所以需要检查OSPF邻居关系是否建立正常。
2.3 在AR29上通过display ospf peer brief 命令检查AR29与AR33的邻居关系是否建立正常,输出结果如下所示:
------------------------------------------------------------------------------------------------------------------------------
<AR29>dis ospf peer brief
OSPF Process 1 with Router ID 10.5.1.29
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
由以上输出结果可知,AR29与AR33没有建立full的邻居关系,需要进一步判断OSPF邻居建立是否出现错误,先排查接口是否发布到OSPF的进程中了。
2.4 检查AR29的相关接口信息,输出结果如下所示:
----------------------------------------------------------------------------------------------------------------
<AR29>dis ospf interface all
。。。。。。
Area: 0.0.0.2 (MPLS TE not enabled)
Interface: 10.5.40.30 (GigabitEthernet0/0/1)
Cost: 1 State: DR Type: Broadcast MTU: 1500
Priority: 1
Designated Router: 10.5.40.30
Backup Designated Router: 0.0.0.0
Timers: Hello 10 , Dead 40 , Poll 120 , Retransmit 5 , Transmit Delay 1 Interface: 10.5.1.29 (LoopBack0)
Cost: 0 State: P-2-P Type: P2P MTU: 1500
Timers: Hello 10 , Dead 40 , Poll 120 , Retransmit 5 , Transmit Delay 1
---------------------------------------------------------------------------------------------------------------- 由以上输出结果可知,AR29的Loopback0和G0/0/1都发布在area 2 中,并且得知G0/0/1接口网络类型是广播型,hello间隔是10s,dead间隔时间是40s,mtu是1500。由于邻居关系的建立依赖于网络层连通性,所以下一步检查路由器之间的网络连通性。
2.5 在AR29上使用ping测试AR29和AR33的接口G0/0/1的网络层通信输出结果如下:
----------------------------------------------------------------------------------------------------------------
<AR29>ping 10.5.40.34
PING 10.5.40.34: 56 data bytes, press CTRL_C to break
Reply from 10.5.40.34: bytes=56 Sequence=1 ttl=255 time=30 ms
Reply from 10.5.40.34: bytes=56 Sequence=2 ttl=255 time=20 ms
Reply from 10.5.40.34: bytes=56 Sequence=3 ttl=255 time=20 ms
Reply from 10.5.40.34: bytes=56 Sequence=4 ttl=255 time=30 ms
Reply from 10.5.40.34: bytes=56 Sequence=5 ttl=255 time=30 ms --- 10.5.40.34 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 20/26/30 ms----------------------------------------------------------------------------------------------------------------
由以上输出结果可知,AR29和AR33的接口G0/0/1的网络层通信正常,所以下一步检查OSPF协议配置的故障信息。
2.6 在AR29上使用命令display ospf error interface g0/0/1来检查OSPF邻居建立是否接收到错误的数据包,测是结果如下所示:
----------------------------------------------------------------------------------------------------------------
<AR29>display ospf error interface g0/0/1
OSPF Process 1 with Router ID 10.5.1.29
OSPF error statistics Interface: GigabitEthernet0/0/1 (10.5.40.30)
General packet errors:
0 : Bad version 0 : Bad checksum
0 : Bad area id 0 : Bad authentication type
0 : Bad authentication key 1 : Unknown neighbor
0 : Bad net segment 6 : Extern option mismatch
0 : Router id confusionHELLO packet errors:
0 : Netmask mismatch 111 : Hello timer mismatch
0 : Dead timer mismatch 0 : Invalid Source Address----------------------------------------------------------------------------------------------------------------
由以上输出课件,AR29于AR33的hello时间不匹配,所以无法正常建立邻居关系,为确定是否还存在其他影响邻居无法建立的因素,需要进一步排查。
2.7 在AR29上打开调试命令来确定AR29和AR33是否存在其他影响邻居关系的建立,测试的输出结果如下:
Sep 28 2020 14:50:57.279.2-08:00 AR29 RM/6/RMDEBUG: Source Address: 10.5.40.34
Sep 28 2020 14:50:57.279.3-08:00 AR29 RM/6/RMDEBUG: Destination Address: 224.0.0.5
Sep 28 2020 14:50:57.279.4-08:00 AR29 RM/6/RMDEBUG: Ver# 2, Type: 1 (Hello)
Sep 28 2020 14:50:57.279.5-08:00 AR29 RM/6/RMDEBUG: Length: 44, Router: 10.5.1.33
Sep 28 2020 14:50:57.279.6-08:00 AR29 RM/6/RMDEBUG: Area: 0.0.0.2, Chksum: 0
Sep 28 2020 14:50:57.279.7-08:00 AR29 RM/6/RMDEBUG: AuType: 02
Sep 28 2020 14:50:57.279.8-08:00 AR29 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Sep 28 2020 14:50:57.279.9-08:00 AR29 RM/6/RMDEBUG: Net Mask: 255.255.255.0
Sep 28 2020 14:50:57.279.10-08:00 AR29 RM/6/RMDEBUG: Hello Int: 15, Option: _N_
Sep 28 2020 14:50:57.279.11-08:00 AR29 RM/6/RMDEBUG: Rtr Priority: 1, Dead Int: 60
Sep 28 2020 14:50:57.279.12-08:00 AR29 RM/6/RMDEBUG: DR: 10.5.40.34
Sep 28 2020 14:50:57.279.13-08:00 AR29 RM/6/RMDEBUG: BDR: 0.0.0.0
Sep 28 2020 14:50:57.279.14-08:00 AR29 RM/6/RMDEBUG: # Attached Neighbors: 0
Sep 28 2020 14:51:02.739.2-08:00 AR29 RM/6/RMDEBUG: Source Address: 10.5.40.30
Sep 28 2020 14:51:02.739.3-08:00 AR29 RM/6/RMDEBUG: Destination Address: 224.0.0.5
Sep 28 2020 14:51:02.739.4-08:00 AR29 RM/6/RMDEBUG: Ver# 2, Type: 1 (Hello)
Sep 28 2020 14:51:02.739.5-08:00 AR29 RM/6/RMDEBUG: Length: 44, Router: 10.5.1.29
Sep 28 2020 14:51:02.739.6-08:00 AR29 RM/6/RMDEBUG: Area: 0.0.0.2, Chksum: 0
Sep 28 2020 14:51:02.739.7-08:00 AR29 RM/6/RMDEBUG: AuType: 02
Sep 28 2020 14:51:02.739.8-08:00 AR29 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Sep 28 2020 14:51:02.739.9-08:00 AR29 RM/6/RMDEBUG: Net Mask: 255.255.255.0
Sep 28 2020 14:51:02.739.10-08:00 AR29 RM/6/RMDEBUG: Hello Int: 10, Option: _E_
Sep 28 2020 14:51:02.739.11-08:00 AR29 RM/6/RMDEBUG: Rtr Priority: 1, Dead Int:40
Sep 28 2020 14:51:02.739.12-08:00 AR29 RM/6/RMDEBUG: DR: 10.5.40.30
Sep 28 2020 14:51:02.739.13-08:00 AR29 RM/6/RMDEBUG: BDR: 0.0.0.0
Sep 28 2020 14:51:02.739.14-08:00 AR29 RM/6/RMDEBUG: # Attached Neighbors: 0
----------------------------------------------------------------------------------------------------------------------------------------- 由以上输出结果可知,AR29和AR33存在hello时间不一致,(Hello Int: 10, Hello Int: 15),并且区域类型不一致(Option: _E_,Option: _N_)。其中AR29被配置为普通区域类型,AR33被配置为了NSSA区域类型。其他影响邻居建立的因素Router-id不冲突、dead time一致、Area信息一致、接口掩码一致、hello报文源地址在一个网段、不存在认证错误。
结论:此故障产生的原因是AR29和AR33的OSPF区域类型配配置不匹配,hello时间不匹配,从而导致无法建立full的邻居关系进而无法计算路由。
三、故障处理
3.1 根据拓扑可知,AR33于AR29处于OSPF区域2中,将AR29的Area2配置为NSSA区域即可:
system-view
ospf 1
area 2
nssa
intterface g0/0/1
ospf timer hello 15
执行完以上命令后在AR29上进行一下测试:
display ospf peer brief
display ip routing-table
ping -a 10.5.1.29 10.5.1.33
3.2 如果以上处理方式仍然不能解决那么还可能存在一下几种高可能性故障:
(1)AR33上Loopback0接口没有加入到OSPF进程中,需要执行以下命令来解决。
sys
ospf 1
area 2
network 10.5.1.33 0.0.0.0
(2)AR29和AR33在OSPF进程下做了路由过滤,需要执行以下命令来解决。
display ospf brief
sys
ospf 1
undo filter-policy xxx import
(3)AR33接口做了过滤策略,需要执行以下命令来解决。
display traffic-filter appiled-record
display traffic-policy appiled-record
sys
int {启用了策略的接口}
undo traffic-policy inbound/outbound
undo traffic-filter inbound/outbound
执行完以上命令后在AR29上进行一下测试:
display ospf peer brief
display ip routing-table
ping -a 10.5.1.29 10.5.1.33
3.3 如果以上命令均不能解决问题则需要用户提供完整的设备配置信息或者直接派遣工程师前往排查,并且拨打华为400服务热线请求华为TAC专家协助故障处理,谢谢!