cisco it exam

cisco it exam

LSPID (support) does not announce the direct connection between R1-R5 and R4-R6 into OSPF Tunnel mpls traffic-eng priority 5 5 Note: a L1 / L2 router if the other area router adjacency relationship, it will to this area of the L1 router advertisement himself outlet, the specific method is the raw cost region L1 LSP when packets ATT bit Set 1 RFC 3787 R1#sh isis neighbors detail Safety and certification Reservable Bandwidth[2]: Path Protection: 2 Common Link(s), 2 Common Node(s) Reservable Bandwidth[1]: 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). The checksum calculation knows the end of the packet starting from the field after the remaining time-to-live field in the LSP . When the LSP copy is propagated between routers in the network, its checksum field is not modified. Tag or VC Of course, not the remote tag in LIB will be used. We also need to combine the FIB table to get the next hop information about the prefix. Finally form the LFIB table: The above is the debug information under normal circumstances . It became untagged , before it was POP , why is it untagged now? Analysis, we modified the R2 's loopback mouth, into 2.2.2.2/24 , then for R2 own, this is the direct route 2.2.2.0/24 , right? R2 may for this 2.2.2.0/24 assign a label, since it is directly connected, so R2 to this prefix divided empty tag 3 . Then send the label mapping message to other LDP neighbors including R1 and R3 : Interface fas0/0 It can prevent the structure of the core transmission network from being exposed due to TTL=0 return error message Network 10.1.12.1 0.0.0.0 area 0 Support 0-7 total 8 tunnel priority levels O 5.5.5.5 [110/31] via 4.4.4.4, 00:23:47, Tunnel0 CLNP is similar to the IP protocol except that it serves the ISO transport layer. IS-IS , ES-IS , and CLNP are network layer protocols that are encapsulated directly in the data link layer frame. Compared with the OSPF packet in TCP/IP , it is hidden behind the IP header. The encapsulation efficiency of the former protocol packet is higher. In the LAN , SNPA refers to the MAC address. Circuit type : 01 means L1 router, 10 means L2 router, 11 means L1/2 router (Link Data) Router Interface address: 0.0.0.13 Number of MTID metrics: 0 Mpls traffic-eng router-id loopback0 mpls traffic-eng area 0 Then just fill in the configuration on R2 . I won't go into details here. Interface fas0/0 Network 3.3.3.3 0.0.0.0 area 0 Provide the best route for the network It became untagged , before it was POP , why is it untagged now? Analysis, we modified the R2 's loopback mouth, into 2.2.2.2/24 , then for R2 own, this is the direct route 2.2.2.0/24 , right? R2 may for this 2.2.2.0/24 assign a label, since it is directly connected, so R2 to this prefix divided empty tag 3 . Then send the label mapping message to other LDP neighbors including R1 and R3 : Explicit empty label Rl , R2 , R3 , R4 running the OSPF , declaring a straight connector, and Loopback interfaces, Loopback port IP of XXXX / 32 , X The trick of traditional IP routing: Configuration example 1 : 10.1.23.0 That is , the direct link of R2-R3 is imported into 49.0001 , but the default route generated by R3 does not come together. Although the L1 / L2 router having both L1 and L2 function, but sometimes simply Establishing a specific interface on a layer adjacent relationship, are arranged on the other interfaces in the first 2 layers adjacent relationship. Clear text interface authentication Let us verify it now. *Aug 18 11:31:44.598: In order for the protection feature to work properly, you need to enable this feature on both LSRs . If one end does not support this feature, you can configure the feature in one segment and the mpls ldp discovery targeted-hello accept command on the other end to receive target-hello . Local tag R2# show ip route ! R1.00-00 *Aug 18 09:06:07.919: Tun Sender: 1.1.1.1 LSP ID: 247 RFC 3277 Checksum: 0x6FEB Length: 132 Note that at this time, although the LDP adjacency between R1 and R2 has been broken, in principle, LDP does not adjacency,cisco it exam, in the case of synchronizing, RFC 3787 If you change the Path-selection metric to igp , the shortest path to the tunnel will ignore the configuration in the physical interface. 10.1.56.5 [MPLS: Label 505 Exp 0] 4 msec 0 msec 0 msec 668 As a result, the Level 1 LSP sent by R1 carries the cipher text authentication TLV . However, since R2 does not enable authentication, the LSPs sent by R1 are sent to R2 . R2 ignores the authentication information in the LSP and directly reads the LSP . Therefore, R2 can learn the route advertised by R1 . Of course, there is no R1 routing. Since everyone learned 4.4.4.4/32 through OSPF , all LSRs will generate a label locally for 4.4.4.4/32 , and then bind this label to the prefix and pass it to other LDP neighbors, as shown in the figure. Current LSP: You can see the main two contents contained in it: one is the directly connected network segment of R1 , here is 10.1.123.0 and 1.1.1.0 , and the other is the direct connection of R1 . Configure targeted-hello accept acl Label 14 OAM alarm tag Remote binding: tsr: 3.3.3.3:0 , tag: 300 tib entry: 2.2.2.2/32, rev 4 Link connected to: a Transit Network R1(config)#key chain test R1(config-keychain)#key 1 Link connected to: a Stub Network Other features of the reserved tags between 0-15 are currently not defined. So our available tags are 16 to 1048575 ( 220-1 ) Route-map test permit 10 router isis Network 10.1.34.4 0.0.0.0 area 0 75000 ! Tunnel mpls traffic-eng autoroute metric relative parsing if the configuration of R2 changes as follows: *Aug 18 04:37:06.239: Flags: 0x0 The process of exchanging LSPs by routers in an area is called flooding . The LSPs received from neighboring routers in the area are stored in the local router. Path calculation The configuration of R3 is as follows: LDP IETF standard ( TCP/UDP port number 646 ) TDP CISCO private ( TCP/UDP port number 711 ) 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. 75000 kbits/sec, Mpls ldp router-id Loopback0 55000 On the L1/L2 router , the routes of the subordinate Level1 area are summarized, so that the summary route is learned in the backbone or level2 area , and the configuration is as above. SRM ( Send Routing Message ): Send routing information message Generating a pseudo-node, node action by the pseudo-elections DIS play 10.1.56.0/24 No bgp default ipv4-unicast neighbor 2.2.2.2 remote-as 2345 Experimental procedure IS-IS hierarchy * 0x0000000C 75000 Set-overload-bit suppress external Net 49.0001.0000.0000.0001.00 Interface fas0/0 Local tag: 104 IS-IS Level-1 Link State Database: IS-IS supports two levels of routing: Level1 and Level2 . Level1 supports routing within the region, Level2 support routing between areas. The Level 2 LSP encapsulates the Level 2 network topology information obtained from the routers connected to the backbone network . The complete Level 2 network topology can be obtained by using the SPF algorithm in the Level 2 link state database . After the configuration is complete, the level 2 LSP sent by R2 will carry the cipher text authentication TLV information (the level 1 LSP is not carried). If this configuration is maintained, we will find that R2 can only learn the R1 release. Routing, this is because level1 LSPs are not authenticated. After completing this experiment, R3 and R4 complete the configuration. 5.5.5.5/32 Since the IP packet destined for 6.6.6.6 is sent to R2 , the IP packet is pushed into the VPN label 505 under the inner layer , which is no problem. Then we continue, the VPNv4 route on 6.6.6.6 on R2 is passed by 5.5.5.5, which is R5 . SENDER_TSPEC 6.6.6.6/32 Uptime: 10 seconds Selection: reoptimization Support for diagnosis of LSP tunnel Different LANs on the DIS . When forwarding, if the destination address is present in the area within, the direct use of L1 LSDB routes generated forward packets, if the destination address is not in the region, the use of this area nearest L1 / L2router as an outlet outside the area network, whereby May cause sub-optimal routing Mpls traffic-eng tunnels ip rsvp bandwidth *Aug 18 11:26:02.546: The work of RSVP continues to work based on the sequence of this IP address. 947 !! 2.2.2.2 The metric of the link is unchanged 3 Mpls traffic-eng tunnels ip rsvp bandwidth Net 49.0001.0000.0000.0002.00 Route-target export 2345:5 !! ldp 's routerid uses loopback port IP Ip address 55.55.55.55 255.255.255.255 RouterID , or the IP address of the interface . The maximum bandwidth is the total bandwidth of the link. In CISCO IOS , this value matches the physical link or the configured bandwidth value. Note that this 303 obviously, is R3 assigned to this allocation result and then to R4 , R4 is with R3 label assigned to pressure to Mpls traffic-eng tunnels mpls label range 400 499 *Aug 18 11:26:02.546: The L1 and L2 IIH PDUs on the LAN are sent to different multicast MAC addresses: L1 is 0180-C200-0014 , L2 is Neighbor 2.2.2.2 update-source Loopback0 Reservable Bandwidth[1]: Untagged Located in the backbone area i L1 2.2.2.0 [115/10] via 10.1.123.2, FastEthernet0/0 5.0.0.0/24 is subnetted, 1 subnets Show isis lsp-log 75M 0x18B7 Intermediate System Intermediate System By default, the IS-IS area is the stub area, which is the latest release. OSPF is LSADB L1 (inside the area) and L2 (in the area) IS-IS extensions for Traffic Engineering LSP Seq Num LSP Checksum LSP Holdtime 103 Interface Ethernet0/0 Value Outgoing Experimental procedure The configuration of R1 is as follows: The OSPF adjacency cannot be established, but R1 has only one available path to reach R2 , so OSPF adjacency is established unconditionally. At the same time, R1 and R2 will directly announce the 10.1.12.0/24 direct link, which will be advertised with the largest metric 65535 . The purpose of this is that if the network environment is a redundant link environment, then the metric of the link can be made the worst from the perspective of the IGP , so that the LDP path bypasses the link.