当我执行时show ip bgp summary，我得到以下数据：

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
12.0.0.2        4   200     199     190        12    0    0 00:17:27        4
2.2.2.2         4   200       0       0        12    0    0 03:06:27        4

你看状态没有什么说明。PfxRcd 是4.

State和是什么意思PfxRcd？

而在Router中12.0.0.2是可以访问的，并且2.2.2.2是不可访问的（我的意思是不能ping），为什么邻居2.2.2.2也得到4前缀路由。

编辑-01

当我显示 bgp 邻居时：

BGP neighbor is 2.2.2.2,  remote AS 200, external link
  BGP version 4, remote router ID 0.0.0.0
  BGP state = Active, up for 08:33:23
  Last read 08:33:23, last write 08:33:23, hold time is 180, keepalive interval is 60 seconds
  Neighbor capabilities:
    Route refresh: advertised and received(new)
    Address family IPv4 Unicast: advertised and received
  Message statistics:
    InQ depth is 0
    OutQ depth is 0

                         Sent       Rcvd
    Opens:                  0          0
    Notifications:          0          0
    Updates:                0          0
    Keepalives:             0          0
    Route Refresh:          0          0
    Total:                  0          0
  Default minimum time between advertisements runs is 30 seconds

 For address family: IPv4 Unicast
  BGP table version 12, neighbor version 6/0
  Output queue size : 0
  Index 1, Offset 0, Mask 0x2
  1 update-group member
                                 Sent       Rcvd
  Prefix activity:               ----       ----
    Prefixes Current:               0          0 (Consumes 0 bytes)
    Prefixes total:                 0          0
    Implicit Withdraw:              0          0
    Explicit Withdraw:              0          0
    Used as bestpath:             n/a          1
    Used as multipath:            n/a          0

                                       Outbound    Inbound
      Local Policy Denied Prefixes:    --------    -------
        Total:                                0          0
      Number of NLRIs in the update sent: max 3, min 1

  Connections established 0; dropped 0
  Last reset never
  Transport(tcp) path-mtu-discovery is enabled
Connection state is ESTAB, I/O status: 1, unread input bytes: 0 
Connection is ECN Disabled, Minimum incoming TTL 0, Outgoing TTL 1
Connection tableid (VRF): 0

Enqueued packets for retransmit: 0, input: 0  mis-ordered: 0 (0 bytes)

Event Timers (current time is 0xC69F4):
Timer          Starts    Wakeups            Next
Retrans             0          0             0x0
TimeWait            0          0             0x0
AckHold             0          0             0x0
SendWnd             0          0             0x0
KeepAlive           0          0             0x0
GiveUp              0          0             0x0
PmtuAger            0          0             0x0
DeadWait            0          0             0x0
Linger              0          0             0x0
ProcessQ            0          0             0x0

iss: 2057115318  snduna: 2057115748  sndnxt: 2057115748     sndwnd:  15955
irs: 3480424370  rcvnxt: 3480424751  rcvwnd:      16004  delrcvwnd:    380

SRTT: 259 ms, RTTO: 579 ms, RTV: 320 ms, KRTT: 0 ms
minRTT: 16 ms, maxRTT: 300 ms, ACK hold: 200 ms
Status Flags: passive open, gen tcbs
Option Flags: nagle, path mtu capable
IP Precedence value : 6

Datagrams (max data segment is 1460 bytes):
Rcvd: 0 (out of order: 0), with data: 0, total data bytes: 0
Sent: 0 (retransmit: 0, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data: 0, total data bytes: 0
 Packets received in fast path: 0, fast processed: 0, slow path: 0
 fast lock acquisition failures: 0, slow path: 0