“假死”现象蔓延 不得不根治? 但是最近几天单位那台连接数字电视前端系统的交换机上也出现了端口“假死”的现象,故障原因很快查清了:是因为该端口下面连接的一台交换机出现了环路,这台CISCO交换机上相应的端口就被系统自动关闭了,这种措势是必要的,因为可以防止环路的扩散,但是当下面的交换机环路故障解除后,该端口并没有又恢复到正常工作状态,更要命的是:一、更换端口; 二、重启交换机都无法实现,因为一来这台交换机上空闲端口很少了,二来这台交换机需要始终处于工作状态,如果一旦重新启动,这几分钟的网络中断就会影响到数字电视的播出,所以是绝对不能重启的。8 ~, N3 J4 C# w
出现了这个问题,我们不得不重视起交换机端口“假死”的现象,寻求在交换机不重启的状态下将该端口“拯救”回来的方法。
! m& ]) h' D- o1 J( L! F& Z/ j 拯救步骤1:查看日志/端口的状态: M) C( u, r' O$ ~- k7 Q* m
登录进入交换机后,执行show log,会看到如下的提示:
4 j9 M) G2 d% ?( z 21w6d: %ETHCNTR-3-LOOP_BACK_DETECTED: Keepalive packet loop-back detected on FastEthernet0/20.
- [8 h* y& a. T6 Z, x8 P) E( _ 21w6d: %PM-4-ERR_DISABLE: loopback error detected on Fa0/20, putting Fa0/20 in err-disable state4 G! B) k) b1 B2 u0 K" t
以上信息就明确表示由于检测到第20端口出现了环路,所以将该端口置于了err-disable状态。
8 B8 B2 E9 b5 P4 e 查看端口的状态" h5 ^; d) d8 c7 S! v
Switch# show inter fa0/20 status3 o7 q- F. c! e- ~
Port Name Status Vlan Duplex Speed Type v5 d, ]+ U; s* a* m
Fa0/20 link to databackup err-disabled 562 auto auto 10/100BaseTX. |2 Y7 ?3 ^* k8 ]5 k+ R& Q8 i
这条信息更加明确的表示了该端口处于err-disabled状态。2 y( X7 t8 z5 `4 l3 s6 G9 s$ Q
既然看到了该端口是被置于了错误的状态了,我们就应该有办法将其再恢复成正常的状态。拯救步骤2:将端口从错误状态中恢复回来
0 j9 e: m4 Y- y( {9 m! J4 F 进入交换机全局配置模式,执行errdisable recovery cause ?,会看到如下信息:
7 C( g6 o( Q) R( S1 C7 l4 n Switch(config)#errdisable recovery cause ?
. Y9 N0 B/ u! x all Enable timer to recover from all causes
! O" d: A! p& {. w, l. a: S8 i bpduguard Enable timer to recover from BPDU Guard error disable state
6 C3 u6 {+ X& e, { channel-misconfig Enable timer to recover from channel misconfig disable state
3 |1 U5 i7 g0 C5 L8 }. J& u! b8 M dhcp-rate-limit Enable timer to recover from dhcp-rate-limit error disable state
, S6 a) k$ J0 A% ~1 k- U0 e dtp-flap Enable timer to recover from dtp-flap error disable state. s$ y- q) L ~, o0 M* l# Q
gbic-invalid Enable timer to recover from invalid GBIC error disable state! }$ K( H' [$ ]0 t! n6 _
l2ptguard Enable timer to recover from l2protocol-tunnel error disable state
& w( c+ g. R) y1 Z/ ~3 X, E; {& @. f; ^ link-flap Enable timer to recover from link-flap error disable state
; l( c) f6 E$ t% t& S loopback Enable timer to recover from loopback detected disable state
3 z& y4 I3 t: V. ?# M pagp-flap Enable timer to recover from pagp-flap error disable state
8 W4 {" Z2 _% k) ~. y8 F psecure-violation Enable timer to recover from psecure violation disable state) @/ j; l+ \5 o' D
security-violation Enable timer to recover from 802.1x violation disable state! r+ k5 K5 p2 A* {; x$ ~
udld Enable timer to recover from udld error disable state$ H+ D% j9 J8 H2 `
unicast-flood Enable timer to recover from unicast flood disable state$ K. _' o; Y$ e
vmps Enable timer to recover from vmps shutdown error disable state |