how many questions in the ccna exam
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Ip vrf forwarding VPN-A
Let's start with a brief introduction:
In the Level1 link state database. Each zone in the IS-IS domain has a unique Level1 link state database. The shortest path is calculated by the SPF algorithm.
*Aug 18 04:37:06.239: ADSPEC type 2 length 48:
ISs flood new LSPs to all neighbors
Network 184.108.40.206 0.0.0.0 area 0
The figure above is a single-area Level1 routing domain.
The attribute used to describe the physical link consists of 32 bits . Each bit can represent an attribute of the link (such as whether it is encrypted or not) or a managed policy. There is no specific syntax for this 32bits . Each bit can be set to the latter without moving it. The network designer can think of specifying a specific meaning for a particular bit as needed .
AFI+IDI is used to identify the Domain
Mpls traffic-eng tunnels mpls label range 200 299
Mpls traffic-eng tunnels ip rsvp bandwidth
Record Route: 220.127.116.11(200) 18.104.22.168(403)
Mpls ldp router-id Loopback0
!! TE metric , the default is equal to the following IGP metric
Or Tunnel Id
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.
Will affect the VPN traffic.
Moreover, it is not necessary to maintain the matching time of both parties when establishing the adjacency relationship.
Static Routing Static Route
Adding the force keyword will take effect immediately. Otherwise, only when the interface selected as the routeriD is DOWN ,how many questions in the ccna exam, the reselection will be performed. Note: The router ID of the LDP neighbor must have reachable routes locally.
In the standard SPF algorithm, there can be multiple equivalent paths to the same destination. We call it ECMP ( Equal-cost Multipath ).
After the above configuration, we will find, R1 can learn to R2 , R3 route, but R2 , R3 between can not learn the route to the peer.
Type 2 length 48:
= 250000 bytes/sec
Now activated R1 is fast-reroute features modified R1 of Tunnel port configured as follows:
Ip address 10.1.23.3 255.255.255.0
Mpls traffic-eng tunnels mpls ip
In IOS , the normal router hello interval defaults to 10S , and the DIS defaults to 3.3S .
Address-family ipv4 vrf VPN-A no synchronization
Last update from 10.1.123.2 on FastEthernet0/0, 00:01:32 ago Routing Descriptor Blocks:
MPLS TE information distribution
When a router receives a tagged message, it searches in the LFIB table. The related matching entries in the LFIB table have outbound actions or labels for the inbound tag, and next hop information. .
Mpls ldp neighbor 22.214.171.124 targeted ldp
MPLS label header. At the same time, the header of the Layer 2 data link layer will be instructed accordingly. For example, the Ethernet data frame, the TYPE field of the MAC layer indicates whether the upper layer data is an mpls label frame (if it is an IPv4 packet, the value is 0x0800 , if it is a label packet) Then it is 8847 -unicast or 8848- multicast)
i ia 126.96.36.199 [115/158] via 10.1.123.2, FastEthernet0/0 10.0.0.0/24 is subnetted, 4 subnets
R1#sh ip os mpls ldp interface fa0/0
188.8.131.52 0 
Select the path with the least number of hops
R2#show ip ospf database router self-originate
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.
Bandwidth , latency , policy constrains
Solution: R1 and R4 use the loopback interface to establish IBGP neighbor relationships.
Local binding: tag: 103 !! Locally assigned label for prefix 184.108.40.206/32
Average rate = 250000 bytes/sec, burst depth = 1000 bytes
R2-PE1# show mpls forwarding-table
PDU length : the length of the entire PDU , including the header
*Aug 18 09:06:02.699: SENDER_TEMPLATE type 7 length 12:
Router ospf 1
Bytes tag switched
Fspec: ave rate=2000 kbits, burst=1000 bytes, peak rate=2000 kbits History:
Finally choose the red path above because the TE metric of this path is smaller
For IS-IS LSP messages and CSNP and PSNP, see the IS-IS Link State Database chapter.
Path MTU: 4294967295
No longer take the tunnel , and then go to traceroute 220.127.116.11 from R2 , no longer see the label.
Router(config)#interface tunnel x
R1#show mpls forwarding-table
Or Tunnel Id
!! Set overload-bit to suppress external routing
*Aug 18 04:37:06.239: Path MTU: 1500
Provide network scalability
Therefore, in the above figure, if R5 sends an IPv4 packet to R3 , R3 can directly identify and hash the source and destination addresses of the Ipv4 header to implement load balancing.
Clear text interface authentication
Administrator-weight , and only the IGP metric is used to calculate the shortest path of the tunnel .
Provide the best route for the network
O 18.104.22.168 [110/2] via 10.1.12.2, 00:00:37, FastEthernet0/0
An IP address.
R1#show ip ospf database opaque-area self-originate
*Aug 18 09:06:07.919: Minimum Path Bandwidth (bytes/sec): 1250000
LDP adjacency establishment process
Type 2 length 36:
Label 14 OAM alarm tag
AutoRoute: disabled LockDown: disabled Loadshare: 0 bw-based auto-bw: disabled
State: Oper; Msgs sent/rcvd: 19/19; Downstream Up time: 00:07:56
A route 10.1.1.0/24 on E was advertised, and now it is summarized on C. The summary route is 10.1.0.0/16 and is advertised to B.
Link connected to: another Router (point-to-point) (Link ID) Neighboring Router ID: 22.214.171.124
Network 10.1.34.4 0.0.0.0 area 0
The interface of each router activates RSVP and MPLS TE tunnel support.
Tib entry: 10.1.12.0/24, rev 4
Tunnel mpls traffic-eng autoroute announce
Res. Global BW: 75000 kbits/sec !! interface's maximum reservable bandwidth
Up Thresholds 15 30 45 60 75 80 85 90 95 96 97 98 99 100
*Aug 18 09:06:07.919:
The first 6 is the setup priority and the second 6 is the hold priority .
Can be modified as the basis for calculating the shortest path of the TE tunnel
Mpls traffic-eng tunnels mpls label range 300 399
Remote binding: tsr: 126.96.36.199:0 , tag: 300 tib entry: 188.8.131.52/32, rev 4
Local binding: tag: 100
Forwarding Adjacency forwarding adjacency
L1 router re-releases external routes into IS-IS
Ip explicit-path name R2R3R4 enable next-address 10.1.12.2
TE router ID of the device
MPLS TE Router ID: 184.108.40.206
220.127.116.11/24 is subnetted, 1 subnets
R2#show mpls forwarding-table
The IS-IS adjacency relationship is established differently for different network types. IS-IS supports the following two types of networks:
Let's look at the picture. If R1 to R6 want to establish a TE tunnel , which is the optimal path, and the bandwidth requirement is 30Mbps , what is the calculation process? First of all, thanks to the flooding of link state information in the zone, " OSPF or IS-IS for MPLS TE extensions ",
The configuration of R2 is supplemented as follows:
Let the ES know where it is, the area prefix
Network 18.104.22.168 0.0.0.0 area 0
The load of the routing processor is low in large areas
Looking at the above topology, we need to establish a TE tunnel between R1 and R5 . Under normal network conditions, we want the tunnel path to be R1-R2-R5 , which is an explicit specified path. In order to make the tunnel path have a backup, we can define a path-option , this path uses the dynamic setting method, let CSPF calculate it by itself, then the configuration is as above.
Retention mode (the Label Retention) : free mode (Liberal Retention)
MPLS TE information distribution
Let's experiment one by one:
The boundary of the area is on the link
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 :
The first label is applied on the ingress LSR and the label belongs to one LSP. The path of the packet through the MPLS network is bound to that one LSP. All that changes is that the top label in the label stack is swapped at each hop The ingress LSR imposes one or more labels on the packet. The intermediate LSRs swap the top label (the incoming label) of the received labeled packet with another label (the outgoing label) and the transmit the packet on the outgoing link. The egress LSR Of the LSP strips off the labels of this LSP and forwards the packet.