编辑推荐：思科交换机经典问题大全

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flyfeng

2007-4-4

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（八）Cisco 网络故障的基本排除方法 (下)

8.与IBM主机连接的Troubleshooting

DLSw+Troubleshooting
STUN Troubleshooting
CIP Troubleshooting
DLSw+Troubleshooting

在用DLSw+通过路由器实现PU2.0/2.1与IBM大型主机之间连接,我们要同时用showdlsw和show interface serial命令解决出现的问题.

首先检查DLSw+定义的两个对等peers是否连通Router#show dlsw peersPeers: state pkts-rx pkts-tx type drops ckts TCP uptime TCP 17.18.15.1 CONNECT 16080 8400 conf 0 0 0 00.03.27 TCP 1.1.12.1 DISCONN 0 0 conf 0 0 0 00.00.00
Peers --- 对应"dlsw remote-peer"定义的对等peers IP地址.state --- 表示与对等peers的连接状态.其中:CONNECT表示对等peers已建立. CAP_EXG表示与远程peer交换性能信息. WAIT_RD是建立peer连接的最后一步,等待远程peer应答信息. DISCONN表示与对等peers没有建立连接,请参阅TCP/IP Troubleshooting检查TCP连接故障. WAN_BUSY表示TCP传输队列已满,不能传输数据.
若对等peers已建立连接,请查看性能交换信息.
Router#show dlsw capabilities
DLSw:Capabilities for peer 172.18.15.166
vendor id (OUI) : '00C' (cisco)
version number : 1
release number : 0
init pacing window : 20
unsupported saps : none
num of tcp sessions :1
loop prevent support : no
icanreach mac-exclusive : no
icanreach netbios-excl. : no
reachable mac addresses : none
reachable netbios names : none
cisco version number : 1
peer group number : 0
border peer capable : no
peer cost : 3
biu-segment configured : no
local-ack configured: yes
priority configured: no
version string :
Cisco Internetwork Operating System Software
IOS (tm) GS Software (GS7-K-M), Experimental Version11.1(10956) [sbales 139]
Copyright (c) 1986-1996 by cisco Systems, Inc.
Compiled Thu 30-May-96 09:12 by sbales8

交换过性能信息后,就要寻找目的MAC地址了,显示出所有的路由器能够到达的MAC地址(本地和远端)Router#show dlsw reachabilityDLSw MAC address reachability cache listMac Addr status Loc. peer/port rif0000.810f.6500 FOUND LOCAL TBridge-001 --no rif--0006.e918.7b70 FOUND LOCAL TBridge-001 --no rif--1000.5ae3.03f7 FOUND LOCAL TBridge-001 --no rif--7500.9221.0000 FOUND REMOTE 16.201.30.250(2065) max-lf(4472)7500.9221.0000 SEARCHING LOCALDLSw NetBIOS Name reachability cache listNetBIOS Name status Loc. peer/port rifSXUSER2 FOUND LOCAL TBridge-001 --no rif--
若本地MAC地址和目的MAC地址状态均是FOUND,请参看第五步.
SEARCHING表示在寻找本地MAC地址或目的MAC地址.此时用show interface serial命令查看该口连接的PU状态.
NOT_FOUND表示没有收到对PU轮询的应答.
VERIFY表示确认缓存内信息.

在SERACHING本地MAC地址或目的MAC地址.Router#show interface serial 0Serial1 is up, line protocol is up Hardware is HD64570 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation SDLC, loopback not set Router link station role: SECONDARY (DTE) Router link station metrics: group poll not enabled poll-wait 40000 seconds N1 (max frame size) 12016 bits modulo 8 sdlc vmac: 4000.5555.00-- sdlc addr C1 state is DISCONNECT cls_state is CLS_STN_CLOSED VS 0, VR 0, Remote VR 0, Current retransmit count 0 Hold queue: 0/200 IFRAMEs 0/0 TESTs 0/0 XIDs 0/0, DMs 0/0 FRMRs 0/0 RNRs 0/0 SNRMs 0/0 DISC/RDs 0/0 REJs 0/0 chain: C1/C1 Last input never, output never, output hang never Last clearing of "show interface" counters never Queueing strategy: fifo Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 packets output, 0 bytes, 0 underruns 0 output errors, 0 collisions, 19 interface resets 0 output buffer failures, 0 output buffers swapped out 6 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up说明:Encapsulation SDLC---串口打包方式为SDLC.Router link station role: SECONDARY (DTE)---目前端口作secondary,由"sdlc role"命令设置.sdlc vmac: 4000.5555.00-- ---由"sdlc vmac"设置的MAC地址.注意它的最后两位是留给PU地址的. 在本例中,端口MAC地址是4000.5555.00C1.sdlc addr C1 state is DISCONNECT ---该端口连接PU C1当前状态.有以下几种状态: DISCONNECT -与PU未连接,次站没有发TEST或XID帧请求建立连接.请检查下面连接的PU是否启动 SNA进程,若是用DCE线缆连接PU请检查线缆是否正确,若是MODEM连接到远端PU上,请检查MODEM状态灯. DISCSENT-路由器发送断开请求(DISC)给次站,正在等待次站应答. SNRMSENT-路由器发送连接请求(SNRM)给次站,正在等待次站应答.这个状态出现在作主站的路由器上.若是在作主站路由器上出现SNRMSENT状态,检查下端PU是否开机,路由器端口与PU上 SDLC口连接的MODEM是否已通(MODEM的DTR,CD,RXD,TXD灯应常亮).一句话,出现SNRMSENT 状态是路由器端口与它下端PU之间问题. CONNECT-PU连接正常.路由器和它连接的次站正常连接. THEMBUSY-PU发送RNR帧.次站告诉路由器暂时不能接收任何信息. USBUSY-路由器发送RNR帧.路由器告诉次站暂时不能接收任何信息.路由器已接收到次站对SNRM帧的应答帧UA,试图建立SDLC或LLC2会话. BOTHBUSY-双方均发送RNR帧.告诉对方暂时不能接收任何信息. ERROR-违反SDLC协议.路由器正在等待次站应答. SNRMSEEN-路由器作次站,接收到SNRM帧.
当双方MAC地址都找到后,开始建立链路了.Router#show dlsw curcuitIndex local addr(lsap) remote addr(dsap) state1818740 1000.5ae3.430d(04) 4000.5555.00c1(04) CONNECTED用"show interface serial"查看PU状态应是"CONNECT".
我们也可以用"debug dlsw"获得更多的信息帮助解决网络中出现的问题.你可以记录下debug传输信息提供给你的代理.

问题:远端没有到达本端机器.远端peer的IP地址是172.18.16.156.

建议:
检查show dlsw peer输出,我们看到:Peers: state pkts-rx pkts-tx type drops ckts TCP uptime TCP 172.18.16.156 DISCONN 0 0 conf 0 0 0 --
用debug dlsw peers命令决定问题:
DLSw:action_a() attempting to connect peer 172.18.15.156(2065)
DLSw:action_a(): Write pipe opened for peer172.18.15.156(2065)
DLSw:peer 172.18.15.156(2065), old state DISCONN, new stateWAIT_RD
DLSw:dlsw_tcpd_fini() for peer 172.18.15.156(2065)
DLSw:tcp fini closing connection for peer 172.18.15.156(2065)
DLSw:action_d(): for peer 172.18.15.156(2065)
DLSw:peer 172.18.15.156(2065), old state WAIT_RD, new stateDISCONN
DLSw:Not promiscuous - Rej conn from 172.18.15.166(2065)
诊断:试着打开peer172.18.15.156,但不成功.DLSw+接收到来自172.18.15.166的打开请求,但是DLSw+拒绝它,因为这个peer没有定义.由此我们可以判断定义peer地址不正确.该peer地址为172.18.15.166就连通了.

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