配置NBMA和P2MP网络类型

<Huawei>system-view
[Huawei]undo info-center enable
[Huawei]sysname AR1
[AR1]interface s1/0/0
[AR1-Serial1/0/0]link-protocol fr
[AR1-Serial1/0/0]fr map ip 10.1.1.2 102 broadcast
[AR1-Serial1/0/0]fr map ip 10.1.1.3 103 broadcast
[AR1-Serial1/0/0]ip address 10.1.1.1 24
[AR1-Serial1/0/0]quit
[AR1]interface LoopBack 0
[AR1-LoopBack0]ip address 1.1.1.1 24
[AR1-LoopBack0]

<AR1>system-view
Enter system view, return user view with Ctrl+Z.
[AR1]ospf router-id 1.1.1.1
[AR1-ospf-1]area 0
[AR1-ospf-1-area-0.0.0.0]network 10.1.1.0 0.0.0.255
[AR1-ospf-1-area-0.0.0.0]network 1.1.1.0 0.0.0.255
[AR1-ospf-1-area-0.0.0.0]quit
[AR1-ospf-1]quit
[AR1]display ospf peer brief

OSPF Process 1 with Router ID 1.1.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
----------------------------------------------------------------------------
[AR1]display ospf interface s1/0/0

OSPF Process 1 with Router ID 1.1.1.1
Interfaces


Interface: 10.1.1.1 (Serial1/0/0)
Cost: 48 State: DR Type: NBMA MTU: 1500
Priority: 1
Designated Router: 10.1.1.1
Backup Designated Router: 0.0.0.0
Timers: Hello 30 , Dead 120 , Poll 120 , Retransmit 5 , Transmit Delay 1
[AR1]ospf
[AR1-ospf-1]peer 10.1.1.2
[AR1-ospf-1]peer 10.1.1.3
[AR1-ospf-1]
<AR1>sys
Enter system view, return user view with Ctrl+Z.
[AR1]ospf
[AR1-ospf-1]undo peer 10.1.1.2
[AR1-ospf-1]undo peer 10.1.1.3
[AR1-ospf-1]quit
[AR1]display ospf peer brief

OSPF Process 1 with Router ID 1.1.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
----------------------------------------------------------------------------
[AR1]interface s1/0/0
[AR1-Serial1/0/0]ospf network-type p2mp
[AR1-Serial1/0/0]quit
[AR1]display ospf peer brief

OSPF Process 1 with Router ID 1.1.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 Serial1/0/0 2.2.2.2 Full
0.0.0.0 Serial1/0/0 3.3.3.3 Full
----------------------------------------------------------------------------
[AR1]quit
<AR1>save

一、OSPF邻居建立失败原因分析
‌NBMA网络类型限制‌

帧中继接口默认网络类型为 ‌NBMA‌，该类型要求手动配置邻居地址且需选举DR/BDR‌1。用户最初配置 peer 10.1.1.2 和 peer 10.1.1.3 但未生效，可能因DR未选举成功或Hello报文无法互通‌
‌验证结果‌：display ospf interface s1/0/0 显示接口类型为NBMA且DR为自身（10.1.1.1），但邻居未形成，表明NBMA模式下静态邻居配置未生效‌
‌P2MP网络类型优化‌

修改接口为 ‌P2MP‌ 类型后，OSPF自动发现邻居且无需DR/BDR选举，成功建立Full状态邻接关系‌
‌关键配置‌：ospf network-type p2mp 直接触发动态邻居发现‌

<Huawei>
<Huawei>system-view
[Huawei]undo info-center enable
Info: Information center is disabled.
[Huawei]sysname AR2
[AR2]interface s1/0/0
[AR2-Serial1/0/0]link-protocol fr
[AR2-Serial1/0/0]fr map ip 10.1.1.1 201 broadcast
[AR2-Serial1/0/0]ip address 10.1.1.2 24
[AR2-Serial1/0/0]quit
[AR2]interface LoopBack 0
[AR2-LoopBack0]ip address 2.2.2.2 24
[AR2-LoopBack0]quit
[AR2]
<AR2>system-view
[AR2]ospf router-id 2.2.2.2
[AR2-ospf-1]area 0
[AR2-ospf-1-area-0.0.0.0]network 10.1.1.0 0.0.0.255
[AR2-ospf-1-area-0.0.0.0]network 2.2.2.0 0.0.0.255
[AR2-ospf-1-area-0.0.0.0]quit
[AR2-ospf-1]quit
[AR2]ospf
[AR2-ospf-1]peer 10.1.1.1
[AR2-ospf-1]quit
[AR2]
<AR2>system-view
[AR2]interface s1/0/0
[AR2-Serial1/0/0]ospf dr-priority 0
[AR2-Serial1/0/0]q
[AR2]ospf
[AR2-ospf-1]undo peer 10.1.1.1
[AR2-ospf-1]quit
[AR2]interface s1/0/0
[AR2-Serial1/0/0]ospf network-type p2mp
[AR2-Serial1/0/0]quit
[AR2]q
<AR2>save

一、OSPF配置关键问题分析
‌DR优先级设置为0的影响‌

接口 s1/0/0 配置 ospf dr-priority 0 后，AR2将不参与DR/BDR选举，导致NBMA模式下无法建立邻接关系‌1。此操作在NBMA网络中会中断OSPF邻居关系，需确保对端设备未依赖AR2作为DR‌

‌P2MP网络类型配置优化‌

修改接口网络类型为 p2mp 后，OSPF通过组播自动发现邻居，无需手动指定 peer 地址‌3。此时需验证两端接口的网络类型一致（均为P2MP）且Hello/Dead计时器匹配（默认30/120秒）‌
‌静态邻居配置冲突‌

用户先配置 peer 10.1.1.1 后又执行 undo peer 10.1.1.1，此操作在NBMA模式下会导致邻居关系中断，但在P2MP模式下动态邻居发现机制可自动恢复邻接‌

<Huawei>
<Huawei>system-view
[Huawei]undo info-center enable
[Huawei]sysname AR3
[AR3]interface s1/0/0
[AR3-Serial1/0/0]link-protocol fr
[AR3-Serial1/0/0]fr map ip 10.1.1.1 301 broadcast
[AR3-Serial1/0/0]ip address 10.1.1.3 24
[AR3-Serial1/0/0]quit
[AR3]interface LoopBack 0
[AR3-LoopBack0]ip address 3.3.3.3 24
[AR3-LoopBack0]quit
[AR3]
<AR3>system-view
Enter system view, return user view with Ctrl+Z.
[AR3]ospf router-id 3.3.3.3
[AR3-ospf-1]area 0
[AR3-ospf-1-area-0.0.0.0]network 10.1.1.0 0.0.0.255
[AR3-ospf-1-area-0.0.0.0]network 3.3.3.0 0.0.0.255
[AR3-ospf-1-area-0.0.0.0]quit
[AR3-ospf-1]
<AR3>system-view
[AR3]interface s1/0/0
[AR3-Serial1/0/0]quit
[AR3]ospf
[AR3-ospf-1]peer 10.1.1.1
[AR3-ospf-1]quit
[AR3]interface s1/0/0
[AR3-Serial1/0/0]ospf dr-priority 0
[AR3-Serial1/0/0]quit
[AR3]ospf
[AR3-ospf-1]undo peer 10.1.1.1
[AR3-ospf-1]quit
[AR3]interface s1/0/0
[AR3-Serial1/0/0]ospf network-type p2mp
[AR3-Serial1/0/0]quit
[AR3]q
<AR3>save

一、关键配置问题分析
‌DR优先级设置为0的冲突‌

接口 s1/0/0 配置 ospf dr-priority 0 后，AR3将不参与DR/BDR选举‌。在 ‌NBMA网络类型‌ 下（默认帧中继接口类型），若对端设备依赖AR3作为DR，会导致邻居无法进入Full状态‌，但后续修改为 ‌P2MP网络类型‌ 后，OSPF不再需要DR/BDR，此配置影响被规避‌
‌静态邻居配置与网络类型冲突‌

用户先配置 peer 10.1.1.1，随后在P2MP模式下执行 undo peer 10.1.1.1。由于P2MP网络类型通过组播自动发现邻居，无需手动指定静态邻居‌，此操作符合优化逻辑‌。若保留静态邻居配置，可能导致协议冲突‌
‌Loopback接口掩码问题‌

LoopBack0 配置为 3.3.3.3/24，掩码范围过大会导致路由发布不精确（如广播地址冲突）。建议改为 ‌32位掩码‌（ip address 3.3.3.3 32）以精确宣告主机路由‌