Layer2-wan-3 Frame-relay

Session 1 Frame-relay Frame Relay
Fr was first standardized in 1990. has replaced the X. Technology, which simplifies the 2nd layer of functionality, is a connectivity-oriented data link technology, to provide high-performance and high-efficiency data transmission import line of technical simplification, it relies on high-level protocol import error correction, shipowner fully utilize today's optical fiber and digital network technology. Only basic error detection functionality is provided. Typical rate within 56k-2m/s.

FR is working on the second tier (data link layer), which is a WAN connectivity standard developed by the National Standardization Association of the International Telecommunication Union Communication Standardization Group. Fr can be said to be a two-tier VPN

1. The connection between the user and the service provider is called the User-network interface (UNI). [Uni:user Network Interface]
2. The connection between remainders of different service providers is called Network-network Interface (NNI). [Nni:network-network Interface]
3. User front-end equipment (CPE) (Customer premises equipment)
4, the Data Terminal equipment (DTE) connects the Frame Relay switch router All as the digital terminal equipment [dte:data Terminal equipment]
5. Data communication equipment (DCE) connecting the router to the Frame Relay switch as a digital device [dce:data circuit-terminating equipment]
6, the type of Frame relay network and ways:
Fr Network is a non-broadcast multi-access (NBMA) network.
Fr connections Run on virtual circuits (VCS), each VC is identified by a data link connection identifier (DLCI). Shipowner maps This DLCI to an IP address. [Dlci:data-link Connection Identifier user Digital Identification]
VC is divided into: Permanent virtual circuit (PVC), switching virtual circuit (SVC).
PVC: Required to be used when transferring data between DTE Remainders via Fr. PVC complies with LAP-D Standard, no control field;
SVC: For intermittent transmission of data between the DTE Remainders via Fr. Consider whether the ISP supports it. SVC complies with LAP-F standard
The topology is as follows:

7. DLCI Data Link Connection identification (Connection Identifier):
The FR Switch associates the DLCI of 2 routers to create 1 PVCs.
DLCI only has local meaning.
The range of DLCI (16-1007) 0-15 and 1008-1023 are reserved, 1019 and 1020 are reserved for broadcast, 1023 reserved for Cisco LMI
0 reserved for the LMI type ANSI and q.933a
DLCI Address Mapping:
To transfer data over FR, you must associate the local DLCI with the destination IP address. Address mapping can be manually statically configured, or dynamically learned to generate. The use of Frame Relay reverse Address Resolution Protocol (IARP) is generally not recommended for dynamic generation, and is not stable in complex networks.


8. Local management Interface (LMI) [lmi:local Management Interface]
LMI is a signaling standard between the CPE and FR Switch Remainders, which manages the connection between devices and maintains connection status. The LMI signaling protocol can advertise the addition and removal of PVCs, as well as the data between frame Relay switches and Frame Relay data terminal Equipment remainders.
LMI is configurable, but the router attempts to self-detect the LMI type used by the FR switch. LMI is divided into three types
Cisco. Cisco.
ANSI T1.617 Annex D. ANSI T1.617 Annex d. ANSI T1.617 Annex d.ansi T1.617 Annex d. ANSI T1.617 Annex D. ANSI T1.617 Annex D. ANSI T1.617 Annex D. ANSI T1.617 Annex D.
ITU-T q.933 Annex a T q.933 Annex at q.933 Annex a T q.933 Annex a T q.933 Annex a T q.933 Annex at q.933 Annex a T q.933 Annex A.
In the Frame Relay switch and the connected Frame Relay data terminal equipment, LMI must be the same, the frame Relay provider (Frame Relay switch) will generally tell the user what kind of LMI they are using
ANSI and q933.a use a DLCI value of 0, and Cisco uses a DLCI of 1023.


9, Inverse ARP (reverse arp, in the Frame Relay also has ARP and I-ARP and other network ARP and R-ARP) through the IP address request DLCI number
After the DTE side learns to the PVC entry through the DCE end, the reverse resolves to the Peer DTE Device Interface IP address, which is turned on by default and the interface command no Frame-relay invers-arp is turned off. Turn off parsing will affect PVC learning first turn on reverse parsing, After the completion of the analysis and then the reverse resolution no off, will cause constant error. If reverse parsing is already present, clear Frame-relay Inarparp is required with the privileged mode command clear Frame-relay
When you turn it off, you get the result: if the other person resolves me, I don't respond. After turning off the reverse-state mapping, all mappings under the FR interface are done by manual configuration.


Session 2 FR Network topology
1, fully connected: Each site is connected to each other
2, Star: Each site connected to the total site, through the total site to communicate
3, part of the interconnection: each site connected to the total site, through the total site to communicate. Sub-sites can be partially connected.




Session 3 Frame Relay forwarding Principle
1, now there is no Frame Relay switch hardware, are using routers instead of Frame Relay switch.
2. The forwarding principle of Frame Relay switch: View Fr-route table

For example, explain the frame-relay principle of forwarding:
1, both ends of the Enterprise gateway device R2, R3 need to configure the frame relay ARP, that is, the destination IP address and the VC (DLCI number) corresponding
2, FR-SW view FR routing table, when receiving a DLCI 100 frame Relay frame from the s4/0 port, view FR routing table found the destination of dlci=100 in the route entry corresponding interface is S4/1, and then forwarded through the S4/1 interface, S4/1 from the DLCI interface into 50 , so that when the R3 received dlci=50 frame know is to give their own, the same R3 return to R2 data frame DLCI=50,R3 view their own frame Relay ARP map found the R2 IP address corresponding to the VC (DLCI=50), so from this VC sent to be FR-SW received, FR-SW received the dlci=50 frame after viewing the Frame Relay routing table found that the dlci=50 frame needs to be emitted from the interface s4/0, and then sent from the s4/0 interface, and DLCI to 100, so that R2 received after the R3 back to their own frame, the completion of the data frame forwarding. (Of course, the value of DLCI is set in advance, you need to FR-SW in the configuration, and both ends of the site exit R devices need to configure Fr ARP mapping, that is, the destination IP corresponding to the VC DLCI number)
The specific configuration is as follows:
First, the FR-SW defines the VC DLCI number, such as R2 to R3 VC Dlci=100,r3 to R2 VC dlci=50.
FR-SW (config) #frame-relay switching open Frame Relay switch feature
FR-SW (config) #interface s4/0 Enter the interface s4/0
FR-SW (config-if) #encapsulation Frame-relay? Interface sealing and Finishing relay default is the Cisco standard, but generally most of the manufacturers of equipment are supported (general recommendations with sub-interfaces, described later)
MFR Multilink Frame Relay Bundle interface multiple Frame Relay bundles, similar to EC multi-port bundling
IETF Use rfc1490/rfc2427 encapsulation IETF public standard

FR-SW (config-if) #frame-relay intf-type DCE configuration Frame Relay interface is DCE, otherwise it will not work
FR-SW (config-if) #frame-relay route interface S4/1 broadcast Frame Relay routing configuration when a s4/0 frame is received from the DLCI=100 interface and forwarded from the S4/1 interface, and turn DLCI to 50 and support broadcast/multicast. If no routing entries are dropped, the packet is not flushed.
FR-SW (config) #exit

FR-SW (config) #interface S4/1
FR-SW (config-if) #encapsulation Frame-relay
FR-SW (config-if) #frame-relay intf-type DCE
FR-SW (config-if) #frame-relay route interface s4/0 from broadcast received S4/1 from dlci=100 forwarding and s4/0, and supported broadcast/multicast.
FR-SW (config) #exit
OK, Frame Relay switch configuration complete

Two, the two ends of the export R configuration
R2 above
R2 (config) #intface s4/0
R2 (config) #ip address 192.168.1.1 255.255.255.0
R2 (config-if) #encapsulation Frame-relay Package fr
R2 (config-if) #no frame-relay inverse-arp switch off FR's I-arp automatic learning function, it is recommended to shut down otherwise complex network problems.
R2 (config-if) #frame-relay map IP 192.168.1.2 100 manually maps the ARP table of FR, which maps the destination ip1.2 in the Out VC100 (dlci=100), That is, just go to the 192.168.1.2 data frame all go dlci=100 VC virtual link. If you have multiple destination IPs for different network segments, you need to create multiple mappings, you need to use subinterfaces, because the primary interface can only configure one IP. As to why DLCI = 100, which is defined by FR-SW, FR-SW sends an LMI data message via the interface to inform both ends R (similar to the LSA message).
R3 above
R2 (config) #intface S4/1
R2 (config) #ip address 192.168.1.2 255.255.255.0
R2 (config-if) #encapsulation Frame-relay Package fr
R2 (config-if) #no Frame-relay inverse-arp
R2 (config-if) #frame-relay map IP 192.168.1.1 50

View Frame Relay Configuration
Fr-sw#show Frame-relay Route
Input Intf input DLCI output Intf output Dlci Status
serial4/0 SERIAL4/1 Active
SERIAL4/1 serial4/0 Active


R2#show Frame-relay Map
serial4/0 (UP): IP 192.168.1.2 DLCI (0x64,0x1840), Static,
CISCO, status defined, active

R3#show Frame-relay Map
SERIAL4/1 (UP): IP 192.168.1.1 DLCI (0X32,0XC20), Static,
CISCO, status defined, active

R2#ping 192.168.1.2 Repeat 9
Type escape sequence to abort.
Sending 9, 100-byte ICMP Echos to 192.168.1.2, timeout is 2 seconds:
!!!!!!!!!
Success rate is percent (9/9), round-trip Min/avg/max = 20/27/64 ms


Session 4 FR-SW Remote connection
The topology is as follows:

1, Frame Relay switch in the long-distance communication will encounter intermediate devices can not recognize frame relay frame and can not transfer data, such as R1 and R2, R3 to establish PVC,R1 for the headquarters of a company in Shanghai, R2, R3 respectively for the Shenzhen branch of two, It is now necessary to connect 2 divisions with the R1 headquarters via FR Technology, but because the FR-SW1 of the ISP in Shanghai and the FR-SW of the ISP in Shenzhen have passed through the iinternet N devices (this is replaced by 2 switches), because these devices do not use FR technology, Can not recognize the data frame fr, resulting in FR-SW1 and FR-SW2 data frame is not able to transfer directly, if you want to transfer two more FR-SW to do a (Ethernet) tunnel, so that the frame relay data transmission is encapsulated as an Ethernet frame in the tunnel transmission (equivalent to the Ethernet frame to do the carrier, and Frame Relay frame in this carrier, the outside of the device does not know what is inside the carrier, but the carrier itself is an Ethernet frame, can be in the Internet encapsulation and transmission.
2, R1 to be connected with R2, R3 respectively. And R2, R3 two branches by each have their own network, network address is not the same (different network segments). This must require that the R1 end device support more than 2 IP addresses, so the frame Relay sub-interface needs to be enabled on the R1 s4/0 interface to configure multiple IP addresses and multiple vcs.
Assume that the R1 headquarters network uses a network of 192.168.1.0/24,R2 subsidiaries using the 192.168.2.0/24,R3 subsidiary network using 192.168.3.0/24
The specific configuration is as follows:
First step, R1 sub-interface
R1 (config) #interface s4/0
R1 (config-if) #encapsulation Frame-relay physical interface requires a binding relay to create a FR sub-interface
R1 (config-if) #exit
R1 (config) #interface s4/0.1?
Multipoint Treat as a multipoint link needs to build multiple VCs (usually with this)
Point-to-Point Treat as a point-to-point link only need to establish a VC when, with the physical port directly do the same
R1 (config) #interface s4/0.1 multipoint create multipoint (VC) sub-interfaces
R1 (config-subif) #no frame-relay inverse-arp off ARP auto-learning
R1 (config-subif) #ip address 192.168.2.1 255.255.255.0 Configure IP addresses connected to R2
R1 (config-subif) #frame-relay map IP 192.168.2.2 122 establish the R2 ARP map for the purpose IP+DLCI
R1 (config) #interface s4/0.2 multipoint
R1 (config-subif) #no Frame-relay inverse-arp
R1 (config-subif) #ip add 192.168.3.1 255.255.255.0 Configure the IP address connected to the R3
R1 (config-subif) #frame-relay map IP 192.168.3.2 123 establish the R3 ARP map for the purpose IP+DLCI
Show Frame-relay Map

The second step, R2, R3 configuration mapping, whether to enable sub-interface to see the specific situation, it is generally recommended to do sub-interface
R2 (config) #interface S4/2
R2 (config-if) #encapsulation Frame-relay
R2 (config-if) #no shutdown
R2 (config-if) #exit
R2 (config) #interface s4/2.1 multipoint
R2 (config-subif) #no Frame-relay inverse-arp
R2 (config-subif) #ip address 192.168.2.2 255.255.255.0
R2 (config-subif) #frame-relay map IP 192.168.2.1 221
R2 (config-subif) #exit
Show Frame-relay Map

R3 (config) #interface S4/3
R3 (config-if) #encapsulation Frame-relay
R3 (config-if) #no shutdown
R3 (config-if) #exit
R3 (config) #interface s4/3.1 multipoint
R3 (config-subif) #no Frame-relay inverse-arp
R3 (config-subif) #ip address 192.168.3.2 255.255.255.0
R3 (config-subif) #frame-relay map IP 192.168.3.1 321
R3 (config-subif) #exit
Show Frame-relay Map

Configure tunnel and Frame-relay on the third, FR-SW1, and FR-SW2
FR-SW1 (config) #frame-relay switching
FR-SW1 (config) #interface s4/0
FR-SW1 (config-if) #encapsulation Frame-relay
FR-SW1 (config-if) #frame-relay intf-type DCE
FR-SW1 (config-if) #frame-relay Route 122 f0/0 888
^
% Invalid input detected at ' ^ ' marker. See the prompt does not have this command, because the outside network interface does not know the FR frame, so can not be outgoing FR frame data, here need to do tunnel tunnel and FR-SW2 to establish a connection to the transmission Fr.
FR-SW1 (config-if) #exit
FR-SW1 (config) #interface f0/0
FR-SW1 (config-if) #ip address 56.1.1.1 255.255.255.0 configuring IP for tunnel interface
FR-SW1 (config-if) #exit
FR-SW1 (config) #interface tunnel 1 Create virtual Tunnel 1 for R1 and R2
FR-SW1 (config-if) #tunnel the interface used by source f0/0 Tunnel 1 f0/0
FR-SW1 (config-if) #tunnel destination 56.1.1.2 tunnel 1 Destination Address 56.1.1.2
FR-SW1 (config-if) #exit
FR-SW1 (config) #interface tunnel 2 Create virtual Tunnel 2 for R1 and R3
FR-SW1 (config-if) #tunnel the interface used by source f0/0 Tunnel 2 f0/0
FR-SW1 (config-if) #tunnel destination 56.1.1.2 tunnel 1 Destination Address 56.1.1.2
FR-SW1 (config-if) #exit
FR-SW1 (config) #interface s4/0
FR-SW1 (config-if) #frame-relay Route 122 Interface Tunnel 1 888 Frame Relay Routing entry (using tunneling), sent to the FR-SW2 (tunnel) address. When a dlci=122 frame is received, it is forwarded through the tunnel 1 port and the DLCI becomes 888.
FR-SW1 (config-if) #frame-relay Route 123 Interface Tunnel 1 999 Frame Relay routing entry (using tunneling), sent to the FR-SW2 (tunnel) address. When a dlci=123 frame is received, it is forwarded through the tunnel 1 port and the DLCI becomes 999.

Fr-sw2
Fr-sw2 (config) #frame-relay switching
Fr-sw2 (config) #interface S4/2
FR-SW2 (config-if) #encapsulation Frame-relay
FR-SW2 (config-if) #frame-relay intf-type DCE
FR-SW2 (config-if) #exit
Fr-sw2 (config) #interface S4/3
FR-SW2 (config-if) #encapsulation Frame-relay
FR-SW2 (config-if) #frame-relay intf-type DCE
FR-SW2 (config-if) #exit
Fr-sw2 (config) #interface f0/0
FR-SW2 (config-if) #no shutdown
FR-SW2 (config-if) #ip address 56.1.1.2 255.255.255.0
FR-SW2 (config-if) #exit
Fr-sw2 (config) #interface tunnel 1 to create tunnel 1 for R1 and R2
FR-SW2 (config-if) #tunnel source f0/0 uses f0/0 as the origin
FR-SW2 (config-if) #tunnel destination 56.1.1.1 Tunnel 1-to-end ip56.1.1.1
FR-SW2 (config-if) #exit
Fr-sw2 (config) #interface Tunnel 2 to create tunnel 2 for R1 and R3
FR-SW2 (config-if) #tunnel source f0/0 uses f0/0 as the origin
FR-SW2 (config-if) #tunnel destination 56.1.1.1 Tunnel 2-to-end ip56.1.1.1
FR-SW2 (config-if) #exit
Fr-sw2 (config) #interface S4/2
FR-SW2 (config-if) #frame-relay Route 221 Interface Tunnel 1 888 create FR Route R2 to R1
FR-SW2 (config-if) #exit
Fr-sw2 (config) #interface S4/3
FR-SW2 (config-if) #frame-relay Route 321 Interface Tunnel 2 999 create FR Route R3 to R1
FR-SW2 (config-if) #exit

Fr-sw2#show Frame-relay Route
Input Intf input DLCI output Intf output Dlci Status
SERIAL4/2 221 Tunnel1 888 Inactive
SERIAL4/3 321 TUNNEL2 999 inactive
Tunnel1 888 SERIAL4/2 221 Inactive
Tunnel2 999 SERIAL4/3 321 Inactive

Fr-sw1#show Frame-relay Route
Input Intf input DLCI output Intf output Dlci Status
serial4/0 122 Tunnel1 888 Inactive
serial4/0 123 Tunnel2 999 inactive
Tunnel1 888 serial4/0 122 Inactive
Tunnel2 999 serial4/0 123 Inactive
Test results, R1PINGR2
R1#ping 192.168.2.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.2, timeout is 2 seconds:
!!!!!

R1pingr3
R1#ping 192.168.3.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.2, timeout is 2 seconds:
!!!!!

The FR is configured correctly.
Show Framr-relay PVC
Show Framr-relay LMI

Re-add: Frame-relay PVC Status
PVC status
Active-on behalf of this section PVC available, to end PVC available
Inactive-on behalf of the local PVC is available, to end PVC is not available
Delete-is not available on behalf of the local PVC, usually because this PVC is not learned through LMI
static-on behalf of the DTE does not have a survival detection between DCE, the DTE Ring DCE unilaterally considers the local interface up, there is no LMI update at this time, all the DTE end-learned PVC entry status becomes static, then the PVC cannot use no keepalive (Keepalive10 seconds one, 30 seconds to get down, because every 15 seconds will send a DCE notification tells you I did not receive keepalive, two times after the down)
To configure the non-detection of the surviving state is required on both ends (client, Frame Relay switch side) connected ports are configured no keepalive, or unilaterally configured, because one party does not carry out LMI messages received and sent to the end of the side of the view that the opposite state failure and the interface in the protocol layer down, The interface status changes to up-down state and cannot send and receive data.

PVC link, interface status for local and remote frame relay switches that correspond to the status of the PVCs:
Local Remote
Active√√ The local PVC is no problem, the remote PVC is no problem
Inactive√x The local PVC is not a problem, the remote PVC fault
Deletex? Description of local PVC fault, remote PVC no problem

Add: In the FR network, the FR main interface and FR's multi-point interface is the default to close CDP, only the peer-to sub-interface default is to open CDP. To enable CDP, you need to enable CDP on the main interface and the multi-point interface, allowing the interface to open the CDP Discovery protocol. Non-open CDP can affect the operation of certain protocols, such as ODR-on-demand routing protocols that require CDP protocol to send and receive messages.

Layer2-wan-3 Frame-relay