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© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-3
教学目标( Objectives )
1. 帧中继( Frame Relay )2. 帧中继术语( Frame Relay Terminology ) *3. 帧中继地址映射( Frame Relay Address Mapping )**4.LMI 操作( LMI Operation )5. 帧中继反向 ARP ( Frame Relay Inverse ARP )** 6. 配置基本的帧中继( Configuring Basic Frame Relay )
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-4
Why need Frame-relay?
路由器上需要多个串口,几条 DDN 线路,就需要几个串口
DDN 线路
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-5
Why need Frame-relay?
• 路由器上只需要一个串口,可以有多条 PVC。
• 当帧中继网络空闲时,可以实现突发量传输。
Frame Relay 网络
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-6
帧中继预览Frame Relay Overview
帧中继用虚电路为面向连接的服务建立连接Virtual circuits make connections for Connection-orie
nted service
帧中继工作在这里Frame Relay works here.
DCE or FrameRelay Switch
CSU/DSU
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-7
帧中继协议族Frame Relay Stack
OSI Reference Model Frame Relay
Physical
Presentation
Session
Transport
Network
Data Link
Application
EIA/TIA-232, EIA/TIA-449, V.35, X.21, EIA/TIA-530
Frame Relay
IP/IPX/AppleTalk, etc.
帧中继工作在 OSI 参考模型的物理层和数据链路层
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-8
帧中继术语Frame Relay Terminology
LocalAccess
Loop=T1
Local AccessLoop=64 kbps
Local AccessLoop=64 kbps
DLCI: 400
PVC
DLCI: 500
LMI100=Active400=Active
LMI100=Active400=Active
DLCI: 200
DLCI: 100PVC
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-9
Frame-relay 的关键: DLCI
1. 通俗地讲: DLCI 可以看成用来表示哪一条 PVC 。
2. 实际上它是数据链路层地址。
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-10
What is DLCI?
Frame Relay 网络
102 201R1
R2
R3R4
1.1.1.1
1.1.1.2
1.1.1.3 1.1.1.4
103
301
204
402
304 403
R1 要发送数据到 R2 ,只要往 DLCI 为 102 的 PVC 上发送数据,也就是帧中的 DLCI 为 102 即可。
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-12
帧中继交换网络:如何实现 PVC?
S0S1
R1 R2102 201
S0 : IN 102 S1:OUT 201
S1 : IN 201 S0:OUT 102
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-13
帧中继术语Frame Relay Terminology
1. 访问速率( Access rate ):连接本地环到帧中继的端口速度。2. 数据链路连接标识( DLCI ):在源和目的设备之间标识逻辑电路的一个数值。3. 本地管理接口( LMI );是客户前端设备和帧中继交换机之间的信令标准,负责管理设备之间的连接、维护设备之间的连接状态。4. 承诺信息速率( CIR ): ISP 提供的有保障的速率。
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-14
帧中继术语Frame Relay Terminology
5. 前向显示拥塞通知( FECN ):当网络发生拥塞的时候,向目的设备发送一个 FECN 数据包,来通知拥塞。6. 后向显示拥塞通知( BECN ):当网络发生拥塞的时候,向源路由器发送一个 BECN 数据包,来通知拥塞。同时按 25% 的比例降低数据报发送速率。7. 允许丢弃指示器( DE ):当路由器检测到拥塞时,帧中继交换机将会首先丢弃那些 DE 位设置为 1 的数据包。
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-15
CSU/DSU
帧中继地址映射Frame Relay Address Mapping
• 从 ISP 获得本地意义的 DLCI 号码• Get locally significant DLCIs from provider
• 把网络地址映射到 DLCI
• Map your network addresses to DLCIs
DLCI: 500 PVC 10.1.1.1
Inverse ARP orFrame Relay map
IP(10.1.1.1)
FrameRelay DLCI (500)
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-16
LMI 类型LMI TYPES
Cisco supports three LMI standards:• Cisco (默认)• ANSI
• Q.933
• 11.2 以后的版本不用指定 LMI 类型,可以自动适应
DLCI: 400PVC
Keepalive
CSU/DSU
DLCI: 500 PVC 10.1.1.1
xLMI500=Active400=Inactive
LMI500=Active400=Inactive
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-17
帧中继反向 ARPFrame Relay Inverse ARP
Frame RelayCloud
1
DLCI=100 DLCI=400
172.168.5.5 172.168.5.7
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-18
帧中继反向 ARPFrame Relay Inverse ARP
2 Status Inquiry 2Status Inquiry
Frame RelayCloud
1
DLCI=100 DLCI=400
172.168.5.5 172.168.5.7
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-19
帧中继反向 ARPFrame Relay Inverse ARP
3Local DLCI 100=Active
4Local DLCI 400=Active
2 Status Inquiry 2Status Inquiry
Frame RelayCloud
1
DLCI=100 DLCI=400
3
172.168.5.5 172.168.5.7
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-20
帧中继反向 ARPFrame Relay Inverse ARP
4Hello, I am 172.168.5.5.
3Local DLCI 100=Active
4Local DLCI 400=Active
2 Status Inquiry 2Status Inquiry
Frame RelayCloud
1
DLCI=100 DLCI=400
3
172.168.5.5 172.168.5.7
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-21
帧中继反向 ARPFrame Relay Inverse ARP
Hello, I am 172.168.5.7.4
5Frame Relay Map
172.168.5.5 DLCI 400 Active
Frame RelayCloudDLCI=100 DLCI=400
Frame Relay Map
172.168.5.7 DLCI 100 Active5
172.168.5.5 172.168.5.7
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-22
帧中继反向 ARPFrame Relay Inverse ARP
Hello, I am 172.168.5.7.4
5Frame Relay Map
172.168.5.5 DLCI 400 Active
Frame RelayCloudDLCI=100 DLCI=400
Frame Relay Map
172.168.5.7 DLCI 100 Active5
Hello, I am 172.168.5.5.6
172.168.5.5 172.168.5.7
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-23
帧中继反向 ARPFrame Relay Inverse ARP
Keepalives Keepalives
Hello, I am 172.168.5.7.4
5Frame Relay Map
172.168.5.5 DLCI 400 Active
Frame RelayCloudDLCI=100 DLCI=400
Frame Relay Map
172.168.5.7 DLCI 100 Active5
Hello, I am 172.168.5.5.6
7 7
172.168.5.5 172.168.5.7
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-24
Rel. 11.2 Router Rel. 10.3 Router
interface Serial10/1 ip address 10.16.0.1 255.255.255.0 encapsulation frame-relay bandwidth 64 frame-relay lmi-type cisco
interface Serial1 ip address 10.16.0.2 255.255.255.0 encapsulation frame-relay bandwidth 64 frame-relay lmi-type cisco
HQ Branch
配置基本的帧中继Configuring Basic Frame Relay
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-26
103 104
R1
R2
R3 R4
1.1.1.1
1.1.1.31.1.1.4
301401
304 403
S0/0
S0/0
S0/1
S0/1 S0/1
S0/2
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-27
要求
1. 在 R2 (模拟帧中继交换机)配置 PVC ,配置由教师拷贝给学生
2. 在 R1/R3/R4 上,配置帧中继封装,互相 ping 通对方的串口即可。
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-28
R1/R3/R4 上的配置
int s0/X
no shut
clock rate 128000
encap frame-relay
ip address 1.1.1.X 255.0.0.0
show frame map :查看 IP 到 DLCI 的映射
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-31
DLCI=110IP address=10.16.0.1/24
p1r1
DLCI=100IP address=10.16.0.2/24
interface Serial1ip address 10.16.0.1 255.255.255.0encapsulation frame-relaybandwidth 64frame-relay map ip 10.16.0.2 110 broadcast
HQ Branch
Configuring a Static Frame Relay Map
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-32
Verifying Frame Relay Operation
• Displays line, protocol, DLCI, and LMI information
Router#show interface s0/0Serial0 is up, line protocol is up Hardware is HD64570 Internet address is 10.140.1.2/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation FRAME-RELAY, loopback not set, keepalive set (10 sec) LMI enq sent 19, LMI stat recvd 20, LMI upd recvd 0, DTE LMI up LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0 LMI DLCI 1023 LMI type is CISCO frame relay DTE FR SVC disabled, LAPF state down Broadcast queue 0/64, broadcasts sent/dropped 8/0, interface broadcasts 5 Last input 00:00:02, output 00:00:02, output hang never Last clearing of "show interface" counters never Queueing strategy: fifo Output queue 0/40, 0 drops; input queue 0/75, 0 drops <Output omitted>
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-33
• Displays LMI information
Router#show frame-relay lmi LMI Statistics for interface Serial0 (Frame Relay DTE) LMI TYPE = CISCO Invalid Unnumbered info 0 Invalid Prot Disc 0 Invalid dummy Call Ref 0 Invalid Msg Type 0 Invalid Status Message 0 Invalid Lock Shift 0 Invalid Information ID 0 Invalid Report IE Len 0 Invalid Report Request 0 Invalid Keep IE Len 0 Num Status Enq. Sent 113100 Num Status msgs Rcvd 113100 Num Update Status Rcvd 0 Num Status Timeouts 0
Verifying Frame Relay Operation (cont.)Verifying Frame Relay Operation (cont.)
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-34
• Displays PVC traffic statistics
Verifying Frame Relay Operation (cont.)Verifying Frame Relay Operation (cont.)
Router#show frame-relay pvc 100
PVC Statistics for interface Serial0 (Frame Relay DTE)
DLCI = 100, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0
input pkts 28 output pkts 10 in bytes 8398 out bytes 1198 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts 10 out bcast bytes 1198 pvc create time 00:03:46, last time pvc status changed 00:03:47
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-35
• Displays the route maps, either static or dynamic
Router#show frame-relay mapSerial0 (up): ip 10.140.1.1 dlci 100(0x64,0x1840), dynamic, broadcast,, status defined, active
Verifying Frame Relay Operation (cont.)Verifying Frame Relay Operation (cont.)
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-37
103 104
R1
R2
R3 R4
1.1.1.1
1.1.1.31.1.1.4
301401
304 403
S0/0
S0/0
S0/1
S0/1 S0/1
S0/2
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-38
要求
1. 在 R2 (模拟帧中继交换机)配置 PVC ,配置由教师拷贝给学生;
2. 在 R1/R3/R4 上,配置帧中继封装,从环回口 ping 通环回口;
3. 注意: R3 和 R4 之间没有 PVC 的存在。
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-39
R1 上的配置
int s0/0no shut
clock rate 128000
encap frame-relay
ip address 1.1.1.1 255.0.0.0
no frame inverse-arp
frame map ip 1.1.1.3 103 broadcast
frame map ip 1.1.1.4 104 broadcast
show frame map :查看 IP 到 DLCI 的映射
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-40
R3 上的配置
int s0/1no shut
clock rate 128000
encap frame-relay
ip address 1.1.1.3 255.0.0.0
no frame inverse-arp
frame map ip 1.1.1.1 301 broadcast
show frame map :查看 IP 到 DLCI 的映射
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-41
R4 上的配置
int s0/1no shut
clock rate 128000
encap frame-relay
ip address 1.1.1.4 255.0.0.0
no frame inverse-arp
frame map ip 1.1.1.1 401 broadcast
show frame map :查看 IP 到 DLCI 的映射
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-42
R1 的 RIP 配置
int loo0
ip add 10.1.1.1 255.0.0.0
router rip
network 10.0.0.0
network 1.0.0.0
show ip route
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-43
R3 的 RIP 配置
int loo0
ip add 30.1.1.1 255.0.0.0
router rip
network 30.0.0.0
network 1.0.0.0
show ip route
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-44
R4 的 RIP 配置
int loo0
ip add 40.1.1.1 255.0.0.0
router rip
network 40.0.0.0
network 1.0.0.0
show ip route ,注意查看下一跳的 IP 地址
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-45
•在 R1 上: ip split-horizon
•R1/R3/R4:show ip route 再注意路由的变化
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-47
问题:广播流量必须被发送到每一条 PVC
Problem: Broadcast traffic must be replicated for each pvc
RoutingUpdate
A C
B
2
3
1
路由更新的可达性问题( Reachability Issues with Routing Updates )
B
C
D
A
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-48
解决可达性问题( Resolving Reachability Issues )
方案( Solution ) :• 在 NBMA 环境下,存在水平分割的问题• Split horizon can cause problems in NBMA environments• 子接口可以解决水平分割的问题• Subinterfaces can resolve split horizon issues• 一个单一的物理接口模拟多个逻辑接口• A single physical interface simulates multiple logical interfaces
Subnet A
Subnet B
Subnet C
S0
PhysicalInterface
S0.1S0.2S0.3
Logical Interface
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-49
配置子接口( Configuring Subinterfaces)
•点到点( Point-to-Point )–子接口充当专线– Subinterfaces act as leased line
– 每一个子接口有自己的子网– Each point-to-point subinterface requires its own
subnet
– 应用在 hub and spoke 拓扑中– Applicable to hub and spoke topologies
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-50
配置子接口( Configuring Subinterfaces)
• 多点( Multipoint )– 向 NBMA 网络一样,不能解决水平分割的问题– Subinterfaces act as NBMA network so they do not resolv
e the split horizon issue
–使用同一子网,可以节省地址空间– Can save address space because uses single subnet
– 应用在 partial-mesh 和 full-mesh 拓扑中– Applicable to partial-mesh and full-mesh topology
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-51
A
10.17.0.1s0.2
B
配置点到点子接口实例( Configuring Point-to-Point Subinterfaces Example
)
interface Serial0 no ip address encapsulation frame-relay!interface Serial0.2 point-to-point ip address 10.17.0.1 255.255.255.0 bandwidth 64 frame-relay interface-dlci 110!interface Serial0.3 point-to-point ip address 10.18.0.1 255.255.255.0 bandwidth 64 frame-relay interface-dlci 120!
s0.310.18.0.1
C
10.17.0.2
10.18.0.2
DLCI=110
DLCI=120
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-52
interface Serial2 no ip address encapsulation frame-relay!interface Serial2.2 multipointmultipoint ip address 10.17.0.1 255.255.255.0 bandwidth 64 frame-relay map ip 10.17.0.2 120 broadcast frame-relay map ip 10.17.0.3 130 broadcast frame-relay map ip 10.17.0.4 140 broadcast
s2.1=10.17.0.2/24s2.2=10.17.0.1/24
s2.1=10.17.0.4/24
s2.1=10.17.0.3/24
RTR1
B
RTR3
RTR4
配置多点子接口实例( Multipoint Subinterfaces Configuration Example )
DLCI=120
DLCI=130
DLCI=140
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-54
103 104
R1
R2
R3 R4
301401
304 403
S0/0
S0/0
S0/1
S0/1 S0/1
S0/2
13.1.1.1/8
13.1.1.3/8
14.1.1.1/8
14.1.1.4/8
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-55
要求
1. 在 R2 (模拟帧中继交换机)配置 PVC ,配置有教师拷贝给学生;
2. 在 R1/R3/R4 上,配置帧中继封装,从环回口 ping 通环回口。
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-56
R1 上的配置
int s0/0• no shut
• clock rate 128000
• encap frame-relay
• no ip address
• no frame inverse-arp
int s0/0.3 point-to-point• ip address 13.1.1.1 255.0.0.0
• frame interface-dlci 103
int s0/0.4 point-to-point• ip address 14.1.1.1 255.0.0.0
• frame interface-dlci 104
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-57
R3 上的配置
int s0/1• no shut
• clock rate 128000
• encap frame-relay
• no ip address
• no frame inverse-arp
int s0/1.1 point-to-point• ip address 13.1.1.3 255.0.0.0
• frame interface-dlci 301
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-58
R4 上的配置
int s0/1• no shut
• clock rate 128000
• encap frame-relay
• no ip address
• no frame inverse-arp
int s0/1.1 point-to-point• ip address 14.1.1.4 255.0.0.0
• frame interface-dlci 401
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-59
R1 的 RIP 配置
int loo0• ip add 10.1.1.1 255.0.0.0
router rip• network 10.0.0.0
• network 13.0.0.0
• network 14.0.0.0
show ip route
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-60
R3 的 RIP 配置
int loo0• ip add 30.1.1.1 255.0.0.0
router rip• network 30.0.0.0
• network 13.0.0.0
show ip route
© 2002, Cisco Systems, Inc. All rights reserved. ICND 2.0—0-61
R4 的 RIP 配置
int loo0• ip add 40.1.1.1 255.0.0.0
router rip• network 40.0.0.0
• network 14.0.0.0
show ip route