이 실습은 하나의 서브인터페이스에 여러 DLCI를 매핑하여 Hub가 여러 Spoke와 통신하는 Multipoint(NBMA) 구조를 구성합니다.
R1 (Hub)
S0/0.1 multipoint
10.1.1.1/24
/ | \
DLCI DLCI DLCI
102 103 104
│ │ │
R2 R3 R4
(모두 10.1.1.0/24 동일 서브넷)
| 학습 포인트 | 설명 |
|---|---|
| Multipoint 서브인터페이스 | 물리 I/F는 그대로, 서브인터페이스로 NBMA 구현 |
| frame-relay map ... broadcast | NBMA에서 라우팅 광고 전달 |
| Split-Horizon 이슈 | 같은 인터페이스로 들어온 광고는 같은 인터페이스로 못 나감 |
| NBMA의 한계 | Spoke 간 직접 통신 시 Hub 경유 필요 |
1. Hub에서 Spoke A가 보낸 라우팅 광고를 Spoke B로 못 보내는 문제
→ no ip split-horizon (RIP/EIGRP)
2. OSPF는 기본 network type이 non-broadcast
→ neighbor 명령으로 수동 지정 필요
→ 또는 point-to-multipoint로 변경 권장
3. broadcast 키워드 빠뜨리면 라우팅 프로토콜 동작 안 함
→ show frame-relay map에서 "broadcast" 표기 확인
show frame-relay map ! broadcast 플래그 확인
show ip route ! 라우팅 학습 확인
show ip ospf interface ! Network type 확인
debug ip ospf adj ! 인접 형성 디버깅
Sub-Interface Multipoint 사용
하나의 네트워크(192.168.100.0/24)에 여러 대 연결 (NBMA)
-----102----R1
/ |
/ 103
/ |
201 / |
R2------- | 192.168.100.0/24
203 / |
/ |
/ 301
/ |
-----302----R3
no ip routing
!
frame-relay switching
!
interface serial 1/0
no shutdown
encapsulation frame-relay
frame-relay intf-type dce
clock rate 1612800
frame-relay route 102 interface serial 1/1 201
frame-relay route 103 interface serial 1/2 301
!
interface serial 1/1
no shutdown
encapsulation frame-relay
frame-relay intf-type dce
clock rate 1612800
frame-relay route 201 interface serial 1/0 102
frame-relay route 203 interface serial 1/2 302
!
interface serial 1/2
no shutdown
encapsulation frame-relay
frame-relay intf-type dce
clock rate 1612800
frame-relay route 301 interface serial 1/0 103
frame-relay route 302 interface serial 1/1 203
interface serial 1/0
no shutdown
encapsulation frame-relay
!
interface serial 1/0.123 multipoint
frame-relay map ip 192.168.100.2 102
frame-relay map ip 192.168.100.3 103
ip address 192.168.100.1 255.255.255.0
interface serial 1/0
no shutdown
encapsulation frame-relay
!
interface serial 1/0.123 multipoint
frame-relay map ip 192.168.100.1 201
frame-relay map ip 192.168.100.3 203
ip address 192.168.100.2 255.255.255.0
interface serial 1/0
no shutdown
encapsulation frame-relay
!
interface serial 1/0.123 multipoint
frame-relay map ip 192.168.100.1 301
frame-relay map ip 192.168.100.2 302
ip address 192.168.100.3 255.255.255.0
R1# show ip route
C 192.168.123.0/24 is directly connected, Serial1/0.123
R1# ping 192.168.123.2
R1# ping 192.168.123.3
R2# show ip route
C 192.168.123.0/24 is directly connected, Serial1/0.123
R2# ping 192.168.123.1
R2# ping 192.168.123.3
R3# show ip route
C 192.168.123.0/24 is directly connected, Serial1/0.123
R3# ping 192.168.123.1
R3# ping 192.168.123.2