ccna sample exam questions answers

ccna sample exam questions answers

10.1.23.0/24 R3.00-00 205 R2#sh mpls tr link-management advertisements Et0/1 Network 6.6.6.6 0.0.0.0 area 0 ! - 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 : 1bit Note CISCO IOS in, LDP will not BGP in IPv4 prefix bundled label. ! Attribute Flags: 0x00000000 Since we have configured link protection on R2 to protect the link between R2-R4 , when the E0/1 port of R2 is shut down , the path error message sent by R2 to R1 indicates that R1 does not need to be removed. Drop the tunnel . So R1 of the tunnel will not be removed. No support for Ip multicast routing Comparison of terms between IS-IS and OSPF : Router isis // Prerequisites for binding a label to a route prefix locally Next-address 10.1.23.3 Pop tag 0/0/0 Link ID:: 0 !! R2 has two direct links to participate in MPLS TE . This is the first, which is F0/0 . 75000 kbits/sec, L1/L2 router re-releases external routes into IS-IS ( to level2 ) 202 Interface fast1/0 ERROR_SPEC Mpls traffic-eng tunnels mpls label range 400 499 14 The loopback0 address space of all devices is xxxx/32 , and x is the device number. Last update from 10.1.123.2 on FastEthernet0/0, 00:01:32 ago Routing Descriptor Blocks: Network 10.1.45.4 0.0.0.0 area 0 Going f.0/0 , the outbound tag used is 200 , while 10.1.35.5 accesses 1.1.1.1 and goes to F1/0 , and the outbound tag used is 400 . 10.1.12.2 Test . 3 : SET-overload 'bit-ON-120 Startup 75000 R1.00-00 If there is a loop (usually a problem with the IGP , such as a misconfiguration of the static route), the TTL in the tag header will prevent the tag packet from being forwarded indefinitely. TLV 22 : Extended intermediate-System Reachability Next, R3 receives the tag package. Similarly, look at your own LFIB : System ID System ID 5 Device Internet segment 10.1.xy.0 / 24 , where xy is the device number, X small y large *Aug 18 04:37:06.243: tspec parameter id = 127, flags = 0, length = 5 OutLabel : Ethernet0/1, 304 Ip address 55.55.55.55 255.255.255.255 *Aug 18 09:06:07.919: HOP type 1 length 12: Bytes tag switched Then, OSI routing begins. When an ES wants to send a packet to another ES , it sends the packet to its directly connected network. Type 2 length 48: IS-IS The link type indicates whether the link is a point-to-point or multiple access link. Global Pool Sub Pool Router isis PUSH is also similarly understood, only for top-level label operations, first the inbound top-level label TTL249 is first decremented by 1 , then the newly pushed label header TTL LSPID R3.02-00 10.1.34.4 668 Therefore, in an NBMA network, such as a frame relay environment, it is strongly recommended to use the P2P sub-interface to run ISIS . The agreement was released as RFC1195 . Create a TE tunnel on R1 , the source is its own loopback0 , and the destination is 4.4.4.4 of R4 . OSP PDU Net 49.0001.0000.0000.0002.00 R1#show mpls forwarding-table Forwarding Adjacency forwarding adjacency My Address: 10.1.12.1 55000 Network 10.1.23.2 0.0.0.0 area 0 mpls traffic-eng router-id loopback0 mpls traffic-eng area 0 In RFC5250 In been described herein: A neighbor Capable IS-opaque and only IF The IF IT sets-O 'bit in the Options The ITS Database Field of the Description packets; The-O' bit the NOT SHOULD BE SET When ignored and the MUST BE Three triggers that may cause the TE tunnel to reoptimize . Net 49.0002.0000.0000.0004.00 Ip address 10.1.45.5 255.255.255.0 Mpls traffic-eng tunnels ip rsvp bandwidth Route-map test permit 10 router isis Fa0/0 ! 75M Precautions: !! The link to the problem , the metric is set to 65535 RSVP path maintenance and removal Session_Attibute In R2 on Ip vrf VPN-A rd 2345:6 75000 10.1.12.2 [MPLS: Label 203 Exp 0] 200 msec 84 msec 136 msec Then from the tunnel0 port, cost=1+1=2 , better, so the routing table of R2 changes: R1#show ip route MPLS TE improves the efficiency of traffic spread across the network, avoiding inadequate and overuse of links. In the SWAP process, after the label is exchanged, the inbound label TTL -1 is then copied to the outbound label TTL . MAC/Encaps=14/18, MRU=1500, Label Stack{204} CA014FEC0008CA004FEC00088847 000CC000 968 To form an adjacency relationship. Label description The above output is the opaque-area LSA of type10 flooded by each router in area0 in this environment . You can take a closer look at it, for example, look at R1 itself to generate LSA10 : Interface eth0 0/0 Mpls traffic-eng router-id loopback0 mpls traffic-eng area 0 i L1 i L2 ... ... ... ... Mpls traffic-eng tunnels ip rsvp bandwidth Bw[3]: R1 has already completed the collection of its own TEDB information, and the calculation process of the tunnel path is completed on R1 . Route Distinguisher: 2345:6 Mpls traffic-eng tunnels ip rsvp bandwidth OSPF checks by embedding the interface MTU field in a DBD packet. Local 0/0/0 R4 routing table: The tag value is 1 , and this tag can appear anywhere on the tag stack, except for the bottom of the stack. 0x2D6E Value 1.0.0.0/24 is subnetted, 1 subnets Tag request object ! Record_route ISO10589 defines how to establish a through Level2 backbone of Level1 to repair a quarantined routing Level1 area. This is mainly achieved by electing a level2- capable router in each area as the area-specified level 2 IS and establishing a special adjacency relationship called virtual adjacency or virtual link between the areas. ! Untagged 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. Let's look at an example: Router ospf 1 Tunnel mpls traffic-eng bandwidth 33000 Address-family ipv4 vrf VPN-A no synchronization 0 kbits/sec Layer 1 and Layer 2 set different metrics. ATT/P/OL Type Tu0 The TCP/IP protocol stack, similar to ES-IS , is done by ARP , ICMP , and DHCP protocols in the TCP/IP stack . Different TLV field values ​​can be included in the LSP to advertise various different routing information. Device Configuration Network 55.55.55.55 area 0 OSPF Router-id 1.1.1.1 ATT/P/OL Is-type level-1 metric-style wide Does it match, verify that the password is correct, the area ID or something. 0xA339 Explicit Path a series of IP configuration, an explicit path in the IP can be an interface IP , it may be MPLS TE Router ID . Next Hop Type block This is 1B , which contains a number of important bits: Outgoing RFC 2210 The Use of RSVP with IETF Intergrated Services RFC3209 RSVP Extension to TE Ip cef Explicit Route: 10.1.12.2 10.1.23.2 10.1.23.3 10.1.34.3 Each IP packet forwarded to a router is the same before and after being forwarded through the router. R1#show isis da R1.00-00 detail (Link ID) Designated Router address: 10.1.23.2 (Link Data) Router Interface address: 10.1.23.2 Number of TOS metrics: 0 Outgoing All routers in the area (except the border router) can only establish neighbor relationships with routers in the area. Local binding: tag: imp-null Interface Tunnel0 Used to request complete LSP information when the database is synchronized on the broadcast link. R1#sh ip rsvp interface TE router ID of the device *Aug 18 09:06:07.919: parameter id=127, flags=0, parameter length=5 C It is also to check the FIB table, find 301 corresponding to the tag outgoing label is PoP and the next hop is D , then the head will pop up labels, which expose the original IPv4 data, C will be to the packet D . Version = 0 length in words = 7 service id = 5, service length = 6 E Remote binding: tsr: 2.2.2.2:0, tag: imp-null remote binding: tsr: 3.3.3.3:0 , tag: 301 !! Change to 33M [115/10] via 10.1.123.2, FastEthernet0/0 The L1 and L2 IIH PDUs on the LAN are sent to different multicast MAC addresses: L1 is 0180-C200-0014 , L2 is 2.2.2.0 [115/20] via 10.1.123.2, FastEthernet0/0 3.0.0.0/24 is subnetted, 1 subnets Next Hop Network 10.1.23.2 0.0.0.0 area 0 Show mpls ldp discovery detail Show mpls ldp parameters Show mpls ldp neighbor *Aug 18 09:06:07.919: *Aug 18 04:37:06.239: Error Value: 0x5 (No route available toward destination) NLPID: Tu0:403 ! *Aug 18 09:06:07.919: SESSION type 7 length 16: Current LSP: *Aug 18 04:37:06.239: Hop Addr: 10.1.12.1 LIH: 0x02000403 The tag value is 1 , and this tag can appear anywhere on the tag stack, except for the bottom of the stack. The configuration of R1 is very critical, let's focus on it: Interface eth 0/0 Priority 2 : 9375000 202 Type escape sequence to abort. Tracing the route to 6.6.6.6 Interface fast1/0 The loopback interface of R2 and R3 comes from this area, so there is no problem with the route of L1 , but is the direct link of R2-R4 and R3-R4 coming in? That's because these are the direct connections of R2 and R3 . You can configure the interface to be on S1 and 0 of R2 and S1/0 of R3 . Look at the LDP neighbor on R2 : R2#show mpls traffic-eng fast-reroute database *Aug 18 09:06:07.919: General Parameters break bit=0 service length=8 1.1.1.1:0 Equivalent load balancing in CEF Bw-based To add: In the above environment, the loopback interface cost=1 , and the cost of all other physical interfaces =10 . Then if we configure: Related standards: 2.2.2.2 Prefix Flooding Protocol: OSPF Header Information:: Link[0 ]:Nbr IGP Id: 10.1.12.2, nbr_node_id:8, gen:51 frag_id 0, Intf Address:10.1.12.1 Fa0/0 Mpls ldp router-id loopback0 mpls label range 100 199 interface fast0/0 Outgoing Options: (No TOS-capability, DC) LS Type: Router Links Frame-relay map ip 10.1.123.2 102 broadcast Router ospf 1 *Aug 18 11:31:44.598: 75000 Mpls traffic-eng router-id loopback0 mpls traffic-eng area 0 Router isis Tag Outgoing tag or VC My Address: 10.1.12.1 Activate the MPLS TE extension for each router's OSPF and manually set the RouterID for MPLS TE . If you want the penultimate hop router to recognize the "explicit empty tag" advertised by the tail router as "explicit empty tag", then you can * Aug 18 04: 37: 06.239 : Outgoing PathTear: !! dismantle tunnel SNPA *Aug 18 04:37:06.239: Incoming PathError: !!R2 sends a patherror message to R1 75000 Bw[4]: 0x10BA 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 : Mpls ip 105 *Aug 18 09:06:02.699: version=0, length in words=7 No output feature configured / / Whether the local will retain all the label mapping messages received from the neighbor in the database Bandwidth: 0 Next Hop For the highest loopback port IP (Tunnel0) Destination: 4.4.4.4 The configuration of R5 is as follows: Exist in the message Label space (the Label Space) : based platform (Per-Platform) 4 Mpls traffic-eng tunnels mpls label range 400 499 Router(config-if)#tunnel mode mpls traffic-eng Only the label mapping message of the route prefix advertised by the next hop neighbor of the optimal route is saved locally. NLPID: Metric: 10 Ip cef Router(config)#interface fast0/0 Fa0/0 *Mar 1 00:00:32.763: ISIS-Upd: Important fields changed If the MPLS payload is an IPv4 or IPv6 packet, CISCO IOS is used in a destination-based load balancing environment. Fa1/0 Oper: up AutoBandwidth RFC 3847 10.1.24.2 10.1.24.4 Ip address 3.3.3.3 255.255.255.255 19 Reservable Bandwidth[0]: IS-IS is IIH Overview Fa0/0 ! 0/0/0 Config Parameters: In-label Out intf/label The IS-IS network layer protocol ID in the ISO protocol stack is 0x83. L Access-list 1 permit 3.3.3.3 Network 10.1.34.4 0.0.0.0 area 0 10.1.23.3 [MPLS: Label 301 Exp 0] 124 msec 96 msec 104 msec 10.1.34.0/24 Ip address 10.1.34.3 255.255.255.0 AutoRoute Allocation pattern (the Label Allocation) : independent control mode (Independent Control) lab environment This will cause the route of R2 to change. The outgoing interface of the route to 5.5.5.5 and 55.55.55.55 becomes e0/1 . So R2 goes to RFC1195 Pop tag Bw[7]: Continue to show it: Similar to the concept of DR in OSPF i L2 The configuration of R5 is as follows: Admin: up Then R1 and R3 receive a label mapping with a prefix of 2.2.2.0/24 and a label of 3 . At the same time, they also received the R2 updated route. Since the loopback interface route is updated by OSPF by default, it is updated in /32 mode. Therefore , the route learned on R1 and R3 about 2.2.2.2 is /32 bit. of. Then this is a problem, my routing entry is 2.2.2.2/32 , but the label message you sent me is 2.2.2.0/24 , it doesn't match, so R1 thinks that the label is going to Not 2.2.2.2 , just give an untagged , just like the LFIB table we saw for R1 . In this way, when R1 receives the label package and goes to 2.2.2.2 ,R1 will pop up the label stack of the label package, then find its own FIB table and forward the message out. This seems to be no problem in this topology, but in many environments,ccna sample exam questions answers, there will be problems, such as MPLS VPN . So how to solve it? Very good, R2 loopback port to an ip ospf network point-2-point , or change the mask.