Frame Relay notes

 

Frame-Rekay ):

Frame relay is a connection-oriented service. It is an industry standard pure L2 data link layer protocol. It uses HDLC encapsulation between connected devices and can process multiple virtual circuits (VC; frame Relay is more effective than X.25. Currently, it is generally considered that frame relay should be used to replace X.25;

 

 

 

 

Virtual link VC (Virtual Circuits): Permanent Virtual link PVC (Permanent VC) and switched Virtual link SVC (Switch VC); Virtual link must be constructed before frame relay is run.

 

 

Interface Type of Frame Relay:

There are two types of anti-frame interfaces: User-Network Interface (UNI) and Network-Network Interface (NNI, UNI is further divided into DCE and DTE (the client of frame relay is always the DTE end). The interfaces at both ends of PVC should also be configured with the DLCI (Data-Link Connection Identifier) number for FR path searching.

 

 

 

Signaling mode:

Frame Relay signaling uses the Local Management Interface protocol (LMS). There are three modes:

Cisco compatibility;

ANSI T1.617 Annex D;

ITU-T Q.933a Annex;

IOS 12.0 and later have the ability to detect the LCM format → you can choose not to specify → but you must be consistent when specified!

 

 

PVC connection mode:

FR can be seen as a P2P link → P2P (FR): There can be only one physical link (PVC) but there can be multiple logical links (DLCI );

Full-Mesh: each two nodes are directly connected, and the Full-Mesh network of N nodes has N * (N-1)/2 connections; full-Mesh is an inevitable choice for high-end users because of its excellent reliability but high cost;

Hub & Spoke: each node (Spoke) is directly connected to only the host (Hub), and the Hub & Spoke network of N nodes has a N-1 connection; hub & Spoke is low in cost but not good in redundancy, and there is a problem that routes cannot be fully accessible when multiple PVC entries exist in an interface due to horizontal separation (it is solved using the Frame Relay subinterface ).

 

 

PVC status:

The election (active), the absence of ed, and the absence of inactive ).

 

 

 

Ing Table ):

Describes the relationship between the DLCI Number of the Local interface (FR L2 address) and the IP address of the peer interface (Route's L3 address): The L3-IP of the peer interface maps to the local L2-DLCI.

 

 

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LAB1: basic configuration (ISP part) of Frame Relay (based on a PVC Hub & Spoke architecture for each physical connection ):

Step 1: configure the frame relay switch:

No FR-SW, simulated with a router;

First, change a vror2 R2. (c) # no ip routing → frame-relay switching;

Then encapsulate frame relay in the interface: (c-I) # encapsulation frame-relay;

Then specify the interface type, and because FR-sw always acts as DCE, you also need to configure the clock. Of course, the interface must also be enabled: (c-I) # frame-relay intf-type dce → clock rate 2000000 → no shutdown;

Then, you can specify the LCM mode of FR: (c-I) # frame-relay lm-type cisco → ensure that the two sides are consistent;

Step 2: configure the FR route on the frame relay switch:

The interface on both sides should have a configuration for rollback: (c-I) # frame-relay route, inputPVC interface, and outgoingPVC; then you can use # show frame-relay route to view the configuration.

 

 

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LAB2: basic configuration of Frame Relay (USER) (a PVC Hub & Spoke architecture based on each physical connection ):

Step 1: configure the user interface:

First, encapsulate frame relay in the interface: (c-I) # encapsulation frame-relay;

Specify the interface type and enable: (c-I) # frame-relay intf-type dte (default, can be left unspecified) → no shutdown;

Hey, do not forget to configure the IP address for the routing interface. Otherwise ...... In addition, the FR-SW is also the switch → both sides to the same network segment;

If necessary, you need to synchronize the two interfaces of the same PVC to the LCM mode: (c-I) # frame-relay lm-type cisco;

Step 2: Test link:

View commands: # show frame-relay pvc and # show frame-relay map.

# Show frame-relay pvc: DLCI = ?...... PVC status = ACTIVE ...... In s0;

# Show frame-relay map: Serail 0 (UP): ip? Dlci? (Ing table )...... Dynamic (ARP), Broadcast (Broadcast mode )...... Active )......

Set the loose intersection to run IGP and Ping :!!!!!

Still disconnected !? Don't pay ......

Step 3: FR automatic direction ARP:

ARP (c-I) # no frame-relay inverse-arp;

Then, manually create a ing table, that is, configure the FR route on the Interface: (c-I) # frame-relay map ip address to output the PVC broadcast.

 

 

 

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LAB3: Three-port FR-SW configuration (Full-mesh ):

Step 1: configure the router interface of the frame relay switch:

First, change a vror2 R2. (c) # no ip routing → frame-relay switching;

Then encapsulate frame relay in the interface: (c-I) # encapsulation frame-relay;

Then specify the interface type, and because FR-sw always acts as DCE, you also need to configure the clock. Of course, the interface must also be enabled: (c-I) # frame-relay intf-type dce → clock rate 2000000 → no shutdown;

Step 2: configure the FR route for the vro on the frame relay switch:

The interface on both sides should be configured with a return configuration: (c-I) # frame-relay route is input to the PVC interface and PVC is output from the interface; then you can use # show frame-relay route to view the configuration;

Step 3: configure the user interface:

First, encapsulate frame relay in the interface: (c-I) # encapsulation frame-relay;

Next, specify the interface type and open (c-I) # frame-relay intf-type dte (which is already default and can be left unspecified) → ip address 100.0.0.0 255.255.255.0 → no shutdown;

Step 4: build a virtual pipeline Tunnel:

Because the Ethernet does not run FR, IP addresses are configured on the Ether port between SW2 and SW3 and Tunnel is built (the role is to encapsulate Ethernet headers → secondary encapsulation on the basis of the original frame, without unblocking) to achieve the tutorial purpose: (c) # interface tunnel 1 → tunnel source 23.0.0.2 → tunnel destination 23.0.0.3 and ...... ;

Step 6: configure the FR route of the PVC from R4 to R5:

Connect to the tunnel pipeline first: (c-I) # frame-relay route into the PVC interface to output Tunnel TDLCI;

ISP (FR-SW) on # show frame-relay route view FR route: tunnel 1 1000 s1 504 active, serial 1 501 tunnel 1 1001 active ...... Mutual Ping test. Pass !!!!!

 

 

 

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LAB4: ARP & Full-Mesh PVC build IGP network:

Step 1: Build topology:

Connect to a LAB;

Step 2: Run IGP:

3-1: RIP over Full-mesh & arp pvc fr Network :...... Built;

3-2: VPN over Full-mesh & arp pvc fr network :( c) # router VPN 100 → network 0.0.0.0; replica LAB2 is the established Broadcast mode. The replica neighbor relationship is successfully established;

3-3: OSPF over Full-mesh & arp pvc fr Network (c) # router ospf 100 → router-id 100.0.0 .? → Network 0.0.0.0 255.255.25.255 area 0 (OSPF is run for all interfaces, and the OSPF anti-mask cannot be omitted). Use the # show ip ospf interface to check which OSPF interfaces are currently running, pay special attention to the OSPF running mode of the interface (network type): the main interface of FR is NBMA (non_broadcast) by default and does not actively send the hello packet of multicast; use # show ip ospf neighbor to view neighbors: OSPF cannot establish neighbors because the OSPF operation mode is NBMA. Solution: Change the OSPF operation mode to BROADCAST → (c) # interface serial 0 → ip ospf network broadcast/point-to-point (MA/BMA network ).

 

 

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LAB5: Use the multi-point interface (MP) instead of the physical interface to build the IGP network:

The configuration methods for multi-point interfaces and physical interfaces are exactly the same (same as LAB4 );

Considering the future development of the network, scalability → compared with LAB4, LAB5 (full-mesh) is recommended in the project );

Main Interface Configuration: (c) # in s 0 → en fr → no ip add → no sh;

Sub-interface configuration: (c) # in s 0.100 multipoint (MP sub-interface) → ip add 100.0.0.1 255.255.255.0 → fr map ip 100.0.0.4 104 B → fr map ip 100.0.0.5 105 B.