传送错误的BGP号码

Question

我对BGP的号码有问题。我们已经在思科ISR4451-X路由器上为不同的ISP配置了两个BGP对等点。一个对等点工作正常，但在第二个对等点，连接的状态总是空闲的。当我查看日志时，我发现传输的是错误的数字：

我已经配置了AS 202 the，但是传输始终是数字23456。

Log Buffer (4096 bytes):
Dec 20 12:52:13.940: BGP_Router: unhandled major event code 128,minor 0
Dec 20 12:52:19.609: BGP: xxx active went from Idle to Active
Dec 20 12:52:19.609: BGP: xxx open active, local address xxx
Dec 20 12:52:19.621: BGP: ses global xxx (0x7F33116D6630:0) act Adding topology IPv4 Unicast:base
Dec 20 12:52:19.621: BGP: ses global xxx (0x7F33116D6630:0) act Send OPEN
Dec 20 12:52:19.621: BGP: xxx active went from Active to OpenSent
Dec 20 12:52:19.621: BGP: xxx active sending OPEN, version 4, my as: 23456, holdtime 180 seconds, ID B99E6022
Dec 20 12:52:19.634: BGP: ses global xxx (0x7F33116D6630:0) act Remote close.
Dec 20 12:52:19.634: BGP: nbr_topo global xxx IPv4 Unicast:base (0x7F33116D6630:0) Not scheduling for GR processing [Peer did not advertise GR cap]
Dec 20 12:52:19.634: %BGP-5-NBR_RESET: Neighbor xxx active reset (Peer closed the session)
Dec 20 12:52:19.634: BGP: ses global xxx (0x7F33116D6630:0) act Reset (Peer closed the session).
Dec 20 12:52:19.634: BGP: nbr_topo global xxx IPv4 Unicast:base (0x7F33116D6630:0) NSF delete stale NSF not active
Dec 20 12:52:19.634: BGP: nbr_topo global xxx IPv4 Unicast:base (0x7F33116D6630:0) NSF no stale paths state is NSF not active
Dec 20 12:52:19.634: BGP: nbr_topo global xxx IPv4 Unicast:base (0x7F33116D6630:0) Resetting ALL counters.
Dec 20 12:52:19.634: BGP: xxx active closing
Dec 20 12:52:19.634: BGP: ses global xxx (0x7F33116D6630:0) act Session close and reset neighbor xxx topostate
Dec 20 12:52:19.634: BGP: nbr_topo global xxx IPv4 Unicast:base (0x7F33116D6630:0) Resetting ALL counters.
Dec 20 12:52:19.634: BGP: xxx active went from OpenSent to Idle
Dec 20 12:52:19.634: %BGP_SESSION-5-ADJCHANGE: neighbor xxx IPv4 Unicast topology base removed from session  Peer closed the session

带有wireshark的监视器捕获输出也显示错误为Number，而BGP通知消息显示Bad Peer AS。

边界网关协议-开放消息

   Marker: ffffffffffffffffffffffffffffffff
   Length: 29
   Type: OPEN Message (1)
   Version: 4
   My AS: 23456
   Hold Time: 180
   BGP Identifier: xxx
   Optional Parameters Length: 0

边界网关协议-通知消息

Marker: ffffffffffffffffffffffffffffffff
Length: 21
Type: NOTIFICATION Message (3)
Major error Code: OPEN Message Error (2)
Minor error Code (Open Message): Bad Peer AS (2)

router bgp 202xxx
bgp router-id xxx
bgp log-neighbor-changes
neighbor xxx remote-as 212xx
neighbor xxx dont-capability-negotiate
neighbor xxx password 7 0337723xxxxxxxx

BGP router identifier xxx, local AS number 202xxx
BGP table version is 1814938, main routing table version 1814938
613561 network entries using 152163128 bytes of memory
613561 path entries using 73627320 bytes of memory
102358/96231 BGP path/bestpath attribute entries using 25384784 bytes of memory
88809 BGP AS-PATH entries using 4146064 bytes of memory
1 BGP ATTR_SET entries using 40 bytes of memory
201 BGP community entries using 7928 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 255329224 total bytes of memory
BGP activity 1988167/1374600 prefixes, 3700228/2473531 paths, scan interval 60 secs


Neighbor    V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down    State/PfxRcd
xxx         4   xxx    0      0        1       0   0    5d04h    Idle
xxx         4   xxx  609982   3337     1814810 0   0    1d01h    613562
xxx         4   xxx     0      0        1       0   0    never    Active

为什么在这个对等点传送错误？

Answer 1

AS23456是一种特殊的ASN，称为"AS_TRANS“。当引入4字节的ASN来处理数量不足时，并不是每个路由器都在运行能够处理这些问题的软件。AS23456被使用，所以只支持2字节ASN的路由器能够正确地处理到4字节ASN的路由，而不需要升级它们。您可以在RFC 4893中阅读更多有关这方面的内容。

我有点惊讶，你的路由器仍然记录，因为它的本地ASN，尽管。4字节作为数字已经成为标准很长时间了。

Answer 2

我认为您的问题是这个命令neighbor xxx dont-capability-negotiate

这将禁用所有功能的协商，其中之一是4字节的neighbor x.x.x.x dont-capability-negotiate four-byte-as。