ccna routing questions

ccna routing questions

If an LSP is continuously destroyed during transmission, it will be continuously cleared by other routers, and the source router will continue to resend. This creates an LSP destruction storm. CISCO IOS allows routers to ignore corrupted LSPs and write errors only to log files locally. Open with the lsp-ignore-errors command. Tunnel destination 4.4.4.4 tunnel mode mpls traffic-eng IS reachability Explicit Route: 10.1.45.5 5.5.5.5 After calculating the path, you need to reserve resources and distribute labels through RSVP . The RSVP path message is transmitted one hop along the calculated PATH and requests resources and labels. Then R7 will give the response and bring the label back. This tag distribution and resource reservation actions are also performed one by one. In this way, an LSP is finally established. Section LAN ID as 1921.6811.1001. 03 . " the routers connected to the multiaccess network (Ethernet) all have the same circuit ID . The circuit ID is a one-octet number that the router uses to uniquely identify the Let's start with a brief introduction: 0x7056 Fa1/0 O *Aug 18 09:06:07.919: SENDER_TSPEC type 2 length 36: Mpls traffic-eng tunnels mpls ip Affinity Bit : 0x0 IGP Metric : 1 ISO10589 Each of our IS generates an LSP , and the first segment of the LSP is numbered 0 . But if my LSP is particularly large, it exceeds the interface. *Aug 18 09:06:02.699: Session Name: R1_t0 1.1.1.1 *Aug 18 09:06:07.919: Outgoing PathTear: Do not need to explain it again? At R4 , R4 pops the top label and forwards the packet to R5. Network 10.1.23.3 0.0.0.0 area 0 HOP Mpls traffic-eng router-id loopback0 Et0/1 i*L1 0.0.0.0/0 [115/10] via 10.1.123.3, FastEthernet0/0 Mpls ldp router-id loopback0 mpls label protocol ldp Ip address 4.4.4.4 255.255.255.255 4 is IPv4 . If it is 6 or IPv6 , the LSR uses this value to determine whether the message is V4 or V6 , and then selects a complex equalization algorithm according to different IP versions. Network 2.2.2.2 0.0.0.0 area 0 Configured in OSPF process mode, this command activates MPLS TE in a specific area. Physical Bandwidth: 100000 kbits/sec Res. Global BW: 75000 kbits/sec Res. Sub BW: 0 kbits/sec Downstream:: ID: path option 10 [248] Router ospf 1 And the link TLV is described for carrying a series of MPLS TE sub-unit of the link TLV , regarding the sub- TLV is described as follows: ATT/P/OL R2 Tunnel mpls traffic-eng autoroute metric absolute 9 0x4F65 IS-IS is IIH Overview Use the above command to view the TE metric. Mpls traffic-eng tunnels mpls label range 200 299 The LDP ID is a 6B field and is the LDP identifier of the LSR . Contains the LSR identifier of 4B and the label space of 2B . TE metric: 1, IGP metric: 1, attribute_flags: 0x0 Metric Type: TE (default) Ip router isis Interface Loopback0 If the headend wants to remove the tunnel , send PATHtear along the tunnel path , and the received node responds to RESVtear , so the tunnel between the two points Just throw the next hop of the traffic that meets the conditions to the tunnel interface. Bandwidth parameter is the bytes as a unit Current LSP: SystemID (DIS) : LAN ID . It consists of the SysID of DIS and a 1- byte pseudonode ID . The LAN ID is used to distinguish the same one. No longer take the tunnel , and then go to traceroute 55.55.55.55 from R2 , no longer see the label. Intra-domain routing protocol discriminator: This is the network layer identifier assigned to IS-IS with a value of 0x83 The configuration of R1 is as follows: Interface eth 0/1 FastEthernet0/0, Src IP addr: 10.1.12.2 Addresses bound to peer LDP Ident: 16 Priority 1 : 9375000 *Aug 18 09:06:07.919: version=0, length in words=7 *Aug 18 11:26:02.546: Link connected to: another Router (point-to-point) (Link ID) Neighboring Router ID: 5.5.5.5 The initial configuration is as above. In the current environment, R1 does not activate fastreroute , and R2 does not deploy a protective tunnel . First, in R1 the debug ip rsvp dump-messages IS-IS supports ISO connectionless network environment, pay attention to the data link is The global configuration command metric-style wide allows the cisco router to run the appropriate IOS version to send LSPs carrying the width. Network 10.1.23.2 0.0.0.0 area 0 Router-id 3.3.3.3 *Aug 18 09:06:07.919: Tun Dest: 5.5.5.5 Tun ID: 0 Ext Tun ID: 1.1.1.1 R1#show ip ospf database opaque-area self-originate Designated IS and PseudoNode The TEDB already has link state information in all areas, so there is no need to use the IGP routing protocol. SENDER_TEMPLATE *Aug 18 09:06:07.919: Path MTU: 1500 Fa0/0 75000 SNPA is equivalent to the Layer 2 address of NSAP or NET . router R1#show mpls traffic-eng tunnels Ip address 2.2.2.2 255.255.255.255 0/0/0 Priority 4 : 9375000 TE 's policy routing is no different from traditional policy routing, and it does not change the routing table traffic forwarding based configuration policy. 3 Type System Id Type Interface IP Address State Holdtime Circuit Id *Aug 18 09:06:02.699: min unit=0 bytes, max pkt size=2147483647 bytes NET 2.0.0.0/32 is subnetted, 1 subnets The IS-IS adjacency relationship is established differently for different network types. IS-IS supports the following two types of networks: Link state information IGP itself supports Mpls traffic-eng router-id Loopback0 mpls traffic-eng area 0 Physical Bandwidth: 100000 kbits/sec Res. Global BW: 75000 kbits/sec Res. Sub BW: 0 kbits/sec Downstream:: Reservable Bandwidth[6]: (Link ID) Network/subnet number: 2.2.2.2 (Link Data) Network Mask: 255.255.255.255 Number of TOS metrics: 0 AFI+IDI is used to identify the Domain Basic architecture Tunnel: Pop tag In this way, in the route of L2 , the route matched by the route-map will be injected into the level1 area , then R1 can learn 5.5.5.0 . Type IA , i.e. isis the interarea route, i.e. isis inter-area routes. Mpls traffic-eng reoptimize events link-up Overview Remote binding: tsr: 2.2.2.2:0, tag: imp-null O bit 129 Path Protection: 2 Common Link(s), 2 Common Node(s) !! Interface priority for electing DIS Form a LAN adjacency: ! Mpls traffic-eng router-id loopback0 mpls traffic-eng area 0 Its ingress and exgress LSRs IS Next, add a PVC between R2 and R3 : TCP connection: 3.3.3.3.41954 - 1.1.1.1.646 Mpls traffic-eng tunnels ip rsvp bandwidth *Aug 18 11:26:02.546: Can be used on R5 : The configuration of R3 is as follows: Interface eth 0/0 IP 10.1.12.0/24 IP 1.1.1.1/32 *Aug 18 09:06:07.919: Flags: (0x7) Local Prot desired, Label Recording, SE Style ! Generate a default route to this device as the egress route by ATT bit with its nearest L1/L2 router Mpls traffic-eng router-id loopback0 mpls traffic-eng area 0 Set-overload-bit The routing table for R1 is as follows: 0/0/1 The interface of each router activates RSVP and MPLS TE tunnel support. LSP Now let's consider another scenario. Suppose we add a physical connection between R1 and R5 . In order to facilitate the experiment, I directly pull a line between R1 and R5 . Everyone has the right to have multiple routers in this new path. Play the imagination and kiss: Local Circuit ID Local circuit ID is a link identifier. The identity of this circuit is assigned by the router that sent the Hello PDU and is unique on the interface of the router. At the other end of the point-to-point link , the local circuit ID in the Hello message may or may not be the same value. First configure R3 : Ip cef InLabel : FastEthernet0/0, 201 !! The inbound label is 201 First configure R3 : Outgoing tag or VC Router ospf 100 Interface eth0 0/0 Checksum: 0x6FEB Length: 132 Link state information IGP itself supports MPLS features 10.1.12.2 Use default-information originate to associate a route-map to conditional notification. Only when the route-map match is established, the default route will be sent . The associated prefix list can be matched in the route-map to match the specific route prefix. The default route is advertised when there is this route in the R3 routing table. Filter_Spec 569 Interface eth 0/0 An IBGP adjacency is established between R1 and R4 . The IBGP adjacency is established on the physical interface. Established between R1 and R5 , R4 and R6 Redistributing via isis 0xE7D9 After completing the above configuration, we find that the is-is neighbor relationships of R2 , R3, and R3 and R4 are UP . This is because the IIH package does not carry TLV information for verification . In addition, the routing table of R3 is empty. Bytes tag switched ! 0xA339 Solution: R1 and R4 use the loopback interface to establish IBGP neighbor relationships. 3bit experimental bits for QoS Label ! Router-id 4.4.4.4 Bytes tag switched R1#traceroute 6.6.6.6 IS-IS Level-1 Link State Database: R3.01-00 So far, the basic configuration has been completed. Now let 's create a TE Tunnel on R2 and R5 : 5.5.5.5 Local tag: 104 R2 (config-router)#authentication key-chain test level-2 R2 (config-router)#authentication mode md5 level-2 10.1.12.2 101 Router router Attribute Flags: 0x00000000 Advertising Router: 1.1.1.1 LS Seq Number: 80000001 LABEL Connection TCP: 2.2.2.2.31044 - 1.1.1.1.646 , indicates that the LDP connection is built on TCP 's 1.1.1.1 source port 646 , to the destination 2.2.2.2 of 31044 ports. Because the 2.2.2.2 address is large, it is the initiator. 75000 Adjacency relationship Up or Down ; PATH R2(config-if)#mpls traffic-eng administrative-weight 100 The tag value is 1 , and this tag can appear anywhere on the tag stack, except for the bottom of the stack. 16 Peak rate *Aug 18 11:26:02.546: 2.2.2.2/32 1/0/0 55.55.55.55 [110/31] via 10.1.23.3, 00:02:29, Ethernet0/1 Local binding: tag: 100 Different TLV field values ​​can be included in the LSP to advertise various different routing information. 10.1.12.2 Meanwhile, in order to avoid loops, R2 in the area level1 when injected these routes will be marked downbit , As a result, R3 receive this LSP , for these routes, it will not flood the backbone inside. Local binding: tag: 101 Src 1.1.1.1, Dst 5.5.5.5, Tun_Id 0, Tun_Instance 9 RSVP Path Info: Ip rsvp bandwidth ISO10589 *Aug 18 04:37:06.239: LSP Holdtime *Aug 18 09:06:07.919: !! Cross-regional words must use loose next hop !! activation Tunnel of forwarding-adjacency Obviously due to the lost and R3 direct link, R1-R3 between the LDP adjacency hung up, in terms of natural LIB table, before R3 pass over the bundled label will be lost,ccna routing questions, and now, if R1-R3 Between the link replies, they have to re-establish LDP adjacency and resend the label bundle. IS-IS metric Mpls traffic-eng tunnels mpls label range 400 499 Setting command 2.2.2.0 [115/20] via 10.1.123.2, FastEthernet0/0 3.0.0.0/24 is subnetted, 1 subnets metric R1#show mpls ldp neighbor !! Set MPLS TE routerID State: Oper; Msgs sent/rcvd: 9/9; Downstream Average output rate based on each tunnel Pop tag Ip address 10.1.56.5 255.255.255.0 Bgp router-id 5.5.5.5 Network 10.1.45.4 0.0.0.0 area 0 mpls traffic-eng router-id loopback0 mpls traffic-eng area 0 Complete MPLS TE configuration on R1 . Look at the example above: A is in the area 49.0001 , B is in 49.0002 , because they are in different areas, so they become Level 2 adjacencies. Maintain adjacencies in the region at the same time. If A is configured: See if you receive HELLO from the other party *Aug 18 04:37:06.239: Path Latency (microseconds):0 Tib entry: 10.1.23.0/24, rev 8 IIH Mpls traffic-eng tunnels mpls label range 500 599 Test 2 : SET-overload-ON-Startup 'bit the wait-for-BGP IS Fa0/0 Src 1.1.1.1, Dst 4.4.4.4, Tun_Id 0, Tun_Instance 2 RSVP Path Info: Frame-relay map ip 10.1.123.3 201 broadcast frame-relay map clns 201 broadcast PDU Although the implicit null tag also uses a tag with a tag value of 3 , tag 3 will never appear in the tag stack of the MPLS message, which is why it is called an implicit null tag. Send PATH message to the downstream every 30S head end The LDP ID is a 6B field and is the LDP identifier of the LSR . Contains the LSR identifier of 4B and the label space of 2B . 75000 Type block This is 1B , which contains a number of important bits: Virtual link Periodically send CSNPs every 10S in the broadcast subnet to flood LSPs Router ospf 1 R1(config-router)#authentication key-chain test level-1 R1(config-router)# authentication mode md5 level-1 ! Information, as shown below: *Aug 18 04:37:06.239: Path Latency (microseconds):0 Certification Information On CISCO IOS 12.4 , Acl tried it with standard and extended access control lists. If it is unsuccessful, even acl permit any will not work. Matching the route with the prefix list is successful. So far, the basic configuration has been completed. Now let 's create a TE Tunnel on R2 : Tunnel mpls traffic-eng path-option 10 dynamic Cross-region TE Tunnel ( OSPF ) IS-IS Level-1 Link State Database: Mpls traffic-eng tunnels mpls label range 100 199 Ip address 1.1.1.1 255.255.255.255 Parameters: 0180-C200-0015 Interface fas0/0 Discovery Sources: MPLS LDP-IGP synchronization is enabled in the IGP process and applied to all interfaces running the IGP . Level1 : Relative to the concept of a single area, consists of L1 routers in this area, and its routing information is published to Backbone . ! 300 After completing the above configuration, we can check that the routing network is now interoperable. Ip vrf VPN-A rd 2345:6 Broadcast network Ip access-list standard accept-ldp permit 1.1.1.1 Labels 0-15 are all reserved labels. Here are some reserved tags that have a specific role: The default on the point to point link 10S sent once IIH . Untag will remove all tag headers and turn them into a pure IP message. 2 The configuration of ip rsvp bandwidth R3 is as follows: Lists the Layer 3 protocol supported by the integrated IS-IS protocol. Currently only CLNP Mpls traffic-eng tunnels mpls label range 400 499 R2.00-00 Interface Ethernet0/0 Configure targeted-hello accept acl TOS 0 Metrics: 65535 L1/L2 router Here are some examples of FEC : Metric Type: TE (default) InLabel : - The configuration of R1 is as follows: Network 10.1.23.2 0.0.0.0 area 0 Record Route: NONE LDP initial/maximum backoff: 15/120 sec LDP loop detection: off *Aug 18 11:26:02.546: Interface tunnel0 When you are in a LSR configured on a TE Tunnel when the LSR becomes this TE tunnel head-end LSR . Next you can specify the destination LSR of the TE Tunnel , and the restrictions it must comply with, such as the guaranteed bandwidth of the tunnel, etc. These related parameters are at the headend LSR . 0/0/0 Device Internet segment 10.1.xy.0 / 24 , where xy is the device number, X small y large Intermediate System to Intermediate System (IS-IS) Cryptographic Authentication 4.4.4.4/32, version 12, epoch 0, cached adjacency 10.1.12.2 Metric Type: TE (default) Router-id 3.3.3.3 Types of. The 7th bit is an internal / external flag, set to 0 to indicate an internal metric, and 1 to be an external metric. Use the detail keyword to view the details of the LFIB forwarding entry, including the Layer 2 information, and all the label content. If you don't add it, you can only see the top label. Mpls traffic-eng tunnels ip rsvp bandwidth Ip address 10.1.12.2 255.255.255.0 Type 1 length 52: ! Restrictions: Use the lockdown keyword (note that the above configuration is configured in the TE tunnel port). 204 Pop Label 5.5.5.5/32 0 Tu0 point2point MAC/Encaps=14/18, MRU=1500, Label Stack{304}, via Et0/1 0E00003017000E00003016108847 00130000 Admin. Weight: 1 0x00000011 Mpls traffic-eng tunnels ip rsvp bandwidth Mpls traffic-eng tunnels ip rsvp bandwidth It can be seen that we allocated 33M bandwidth for the tunnel with priority 6. The total reserved bandwidth of the original interface is 75M , and it is divided into 33M , so there is 42M . We can also see because we have modified the priority. The reservable bandwidth of the tunnel of level 6 is therefore lower, and the reserved bandwidth is also changed. Will affect the VPN traffic. Modify the bandwidth UP/DOWN threshold Then apply the ACL on R2 , connect to the interface of R1 , in the direction LSP ( LinkState Protocol Data Unit ) format Net 49.0003.0000.0000.0005.00 Now let 's take the traffic going to 4.4.4.4 on the R1 to the tunnel , using one of the simplest methods: static routing. [115/20] via 10.1.24.2, Serial0/0 All routers in the LAN advertise their own connectivity to the pseudonodes in their LSPs (the adjacency relationship between themselves and the pseudonodes) Tunnel mpls traffic-eng path-option 10 dynamic Ip unnumbered Loopback0 Then configure it on R1 : Interface FastEthernet0/0 Let's start with a brief introduction: Mpls traffic-eng tunnels ip rsvp bandwidth *Mar 1 00:00:32.759: ISIS-Upd: Building L2 LSP Basic configuration If the payload of the MPLS is an IPv4 packet, load balancing is implemented by hashing the source and destination IP addresses of the IPv4 packet header . Mpls traffic-eng tunnels mpls label range 200 299 R1#debug isis adj-packets Router(config)# mpls ldp session protection for acl-peer duration sencondes Mpls traffic-eng router-id loopback0 mpls traffic-eng area 0 Frame-relay map clns 103 broadcast no frame-relay inverse-arp Outgoing Ip address 10.1.34.4 255.255.255.0 MC Therefore, R1 will only use R4 's label mapping for 3.3.3.3 , that is, use label 404 to send the label packet to 3.3.3.3 . *Aug 18 09:06:07.919: Tun Sender: 1.1.1.1 LSP ID: 247 Name: R1_t0 Status: I/E Router ospf 1 RFC1195 Bw[2]: Bandwidth change The hostname can be used in the ID instead of the SysID section. This brings great convenience to our network maintenance and troubleshooting. *Aug 18 11:26:02.546: *Mar 1 00:00:32.759: ISIS-Upd: Important fields changed 4.4.4.4/32 ! Mpls ldp router-id Loopback0 Tib entry: 1.1.1.1/32, rev 2 The label that the tail router advertises to the penultimate hop router is "explicit empty label". However, if the penultimate hop router runs CISCO IOS , it will understand this in the form of an implicit null label, that is, By default, in the TE tunnel, the message sent by the penultimate router to the tail router is unlabeled (or the top label has been removed). To meet the above requirements, IS-IS is designed as a link state routing protocol and uses the SPF shortest path first algorithm to achieve fast convergence and loop-free networks. Network 10.1.24.2 0.0.0.0 area 0 i L2 3.3.3.0 [115/20] via 10.1.34.3, Serial0/1 O 5.5.5.5 [110/31] via 4.4.4.4, 00:23:47, Tunnel0 Brief introduction to the work process C 10.1.24.0 is directly connected, Serial0/0 C 10.1.45.0 is directly connected, Serial0/2 C 10.1.34.0 is directly connected, Serial0/1 i L2 10.1.123.0 [115/20] via 10.1.34.3, Serial0/ 1 Next-address 10.1.23.3 Mpls traffic-eng tunnels ip rsvp bandwidth Total Allocated BW (kbps) Pop tag Ip address 3.3.3.3 255.255.255.0 ip router isis Type 1 length 12: Ip cef The configuration of RouterB is as follows: 5.5.5.5 Tun ID: 0 Ext Tun ID: 1.1.1.1 Ip cef 300 10.1.13.3 Note: The tunnel 's build priority cannot be set higher than the hold priority. Outgoing The configuration of R4 is as follows: IS reachability 10.1.12.2 [MPLS: Label 201 Exp 0] 132 msec 184 msec 88 msec Then, R4 goes to 5.5.5.5 and the next hop is 10.1.12.1 . When 6.6.6.6 accesses 5.5.5.5 , the IP packet arrives at R4 . R4 checks the CEF and labels the IP packet. The key is On this label, R4 will use the label of 10.1.12.0 for this route ( 12.0 is the next hop to 5.5.5.5 ), and this label is assigned by R3 (the label I give to the export data is always the LDP neighbor. s Mark).