Router problem:
1. When do you use multiple ways of agreement?
When two different routing protocols are swapped, multiple route protocols are used. Of course, routing redistribution can also exchange routing information. The following cases don't have to use multiple route protocols:
Upgrade from the old version of the internal gateway protocol (Interior Gateway Protocol, I g P) to the new version of I g P.
You want to use another routing agreement but must retain the original protocol.
You want to terminate internal routing to avoid interference from other routers without strict filtering regulatory functions.
You are in an environment composed of a plurality of manufacturers' routers.
What is the distance vector routing agreement?
The distance vector routing protocol is designed for a small network environment. In large network environments, such protocols are learning routing and maintaining routing will result in large traffic, accounting for too much bandwidth. If the routing selection table update sent by the neighboring site is not received in 9 0 seconds, it considers that the adjacent site is unreachable. Every 30 seconds, the distance vector routing protocol will send the entire routing table to the adjacent site, so that the routing table of the neighboring site is updated. This way, it can collect a list of networks from other sites (directly connected or otherwise) to make routing. The distance vector routing protocol uses the number of hops as a metric to calculate the number of routers to go through the destination.
For example, R i P determines the shortest path using the B E L M a N - F O R D algorithm, that is, as long as the minimum hop number is passed, the destination is reached. The maximum allowable number of hops is usually set to 1 5. Those terminals that must pass more than 1 5 routers are considered to be irreparable.
The distance vector routing protocol has the following: IP RIP, IPX RIP, A P L e Talk RT M P and I G R P.
What is a link state routing protocol?
The link status routing protocol is more suitable for large networks, but due to its complexity, the router requires more C P u resources. It can find a broken link or a newly connected router in a shorter time, so that the aggregation time ratio distance vector routing protocol is shorter. Typically, there is no HE E L Lo message from the neighboring station within 1 0 seconds, which is considered that the neighboring station is not arrival. A link status router sends a new message to its neighboring station to inform all links it know. It determines that the metric value of the optimal path is a value price, and the value of this price is generally determined by the bandwidth of the link. Links with minimum costs are considered optimal. In the shortest path priority algorithm, the maximum possible price can be almost unlimited.
If there is no change in the network, the router can only refresh the route selection table without updated routing tables (the length of the cycle can range from 3 0 minutes to 2 hours).
The link status routing protocol has the following: IP OSPF, IPX NLSP, and I S - I S.
A router can use both distance vector routing protocols and use link status routing protocols?
can. Each interface can be configured to use different routing protocols; however, they must be able to exchange routing information by redistributing routes. (Route redistribution will be discussed later in this chapter.)
2, what is the access sheet?
Access table is a series of control packets joined by the manager to enter and output the rules in the router. It is not generated by the router. Access tables can allow or disable packets from entering or output to destination. The entry of the access table is executed in order, that is, the packet is coming, first look at whether it is constrained by the first item, if not, then execute it down; if it matches the first table item, no matter It is allowed to be prohibited or not, there is no need to perform the check of the following items.
Each protocol of each interface can only have an access table.
What types of access tables are supported?
An access table can be determined by its number. The specific protocol and its corresponding access table numbers are as follows:
◎ I P Standard Access Table Number: 1 ~ 9 9
◎ I P extended access table number: 1 0 0 ~ 1 9 9 ◎ I P x Standard Access table number: 8 0 0 ~ 8 9 9
◎ I P x expansion access table number: 1 0 0 0 ~ 1 0 9 9
◎ AppleTa L K Access table number: 6 0 0 ~ 6 9 9
Tip In Cisco iOS Release11.2 or above, you can use a nameless access table to determine the number of access tables from 1 to 199.
How to create an IP standard access table?
An IP standard access table can be done by the following command: Access-list access number {permit | deny} Source [Source-Mask]
In this order:
◎ Access List Number: Determine which access table belongs to this entry. It is a number from 1 to 9 9.
◎ Permit | DENY: Indicates that this entrance is allowed to block information traffic from a particular address.
◎ Source: Determine the source I P address.
◎ S O U R C E - M A S K: Determining which bits in the address are used to match. If a bit is "1", it indicates that the bit bit does not need to be used, if "0", indicating that the bit bit will be used to match. You can use wildcards.
The following is an access sheet example in a router configuration file:
Router # show access-lis
Standard IP Access List 1
Deny 204.59.144.0, Wildcard Bits 0.0.0.255
Permit Any
3. When is the route redistribution?
Routing redistributions are usually configured on routers responsible for learning routing from a self-government system and then broadcast to another autonomous system. If you are using I G R p or E G R p, routing redistribution is usually automated.
4, what is management distance?
Management distance refers to a routing credibility of a routing protocol. Each routing protocol is high to low according to reliability, and assign a trust level in turn. This trust level is called management distance. For two different routing protocols to a destination, the router first determines which protocol is determined according to the management distance.
6. How to configure redistribution?
You must first: before the routing is redistributed.
1) Decide where to add a new protocol.
2) Determine the Autonomous System Boundary Router (ASBR).
3) Decide which protocol is at the core, which is on the boundary.
4) The decision is performed in the direction of routing.
You can use the following command to redistribute the route update (this example is for OSPF):
Router (config-router) #redistribute protocol [process-id] [metric metric - value] [metric-type type - value] [subnet]
In this command:
◎ Protocol: Specifies the source routing protocol that specifies the router to make routing.
The main values are: BGP, EQP, IGRP, ISIS, OSPF, STATIC [IP], Connected, and RIP.
◎ Process-id: Indicates the process ID of OSPF.
◎ Metric: is an optional parameter to indicate the measure value of the reassigned route. The default metric is 0.
7. Why is it important to determine the adjacent router?
Determining adjacent routers in a small network is not a major problem. Because when a router fails, other routers can converge in an acceptable time. However, in a large network, it is possible to find a fault router. It is known that the adjacent router can accelerate convergence because the router can know more quickly, because the interval between the Hello packet is shorter than the router exchange information. The router using the distance vector routing protocol is not allowed to be adjacent to the router when the adjacent router does not send routing update information. This time is generally 10 ~ 90 seconds. The router using the link state routing protocol does not receive the Hello message, it can be found that the adjacent router is not up to 10 seconds.
How does the distance vector routing protocol and link status routing protocol discovers the router?
The router using the distance vector routing protocol is to create a routing table (which includes a network that is directly connected to it), and it sends this routing table to the router that is directly connected to it. The adjacent router will incorporate the routing table into its own routing table, and it also wants to send its own routing table to its adjacent router. The router using the link status routing protocol To create a link status table, including a list of the entire network destination station. In the update message, each router sends its entire list. When the adjacent router receives this update message, it copies the contents, while sending information to its neighboring station. There is no need to recalculate when the content of the routing table is forwarded.
Note that the Hello packets are broadcast using IGRP and EIGRP routers to discover the neighbors, while swaping routing updates like OSPF. EIGRP Saves an neighbor table for each network layer protocol, which includes the address of the neighboring station, and the number of packets sent by the queue, receives the average time required to send packets from the neighboring station, and When it is determined that the link is not received from the neighboring station before the link is turned off.
8, what is a self-government system?
A autonomous system is router and network groups under a management mechanism control. It can be a router directly connected to a LAN and is also connected to the Internet; it can be a multiple local area network interconnected by the company's backbone. All routers in a self-governing system must be connected to each other, run the same routing protocol, and assign the same autonomous system number. Links between autonomous systems use external routing protocols, such as B g P.
9, what is BGP?
BGP (Border GatewayProtocol) is a routing protocol for dynamically exchange routing information between autonomous systems. The classic definition of a self-governing system is a set of routers under a management mechanism control, which uses IGP and normal metric to forward packets to other autonomous systems.
This term is to emphasize such a fact that the management of a self-government is a unified internal selection plan for other autonomous systems, which provides a consistent description.
10. The type of session supported by BGP?
The session between the BGP adjacent routers is based on the TCP protocol. The TCP protocol provides a reliable transmission mechanism that supports two types of sessions:
o External BGP (EBGP): a session between routers belonging to two different autonomous systems. These routers are adjacent to the same media and subnets.
o Internal BGP (IBGP): is a session between routers within a self-government system. It is used to coordinate and synchronize the process of routing and synchronize within the autonomous system. The BGP router can be separated by several routers at any position of the autonomous system.
Note "The content of the initial data stream is the entire BGP routing table. But when the routing table changes, the router only transmits the changed part. BGP does not need to update the entire routing table periodically. So, in the connection established, one The BGP sender must save the entire BGP routing table with all currently all-level routers. The BGP router periodically sends a Keep Alive message to confirm that the connection is activated. When an error or special case occurs, the router sends a Notification message. When a When an incorrect connection occurs, a Notification message is generated and the connection is disconnected. "- From RFC11654, BGP * works. 11. Is BGP Allow Routing to allocate?
allow. Because BGP is primarily used to router between the autonomous systems, it must support the synthesis of routing tables for RIP, OSPF, and IGRP to transfer their routing tables into a self-government system. BGP is an external routing protocol, so its * is different from an internal routing protocol. In BGP, a route can be created in the BGP routing table if a routing already exists in an IP routing table.
12. How to display all BGP routes in the database?
To display all BGP routes in the database, simply enter from the EXEC command line:
SHOW IP BGP PATHS
The output of this command may be:
Address Hash Refcount MetricPath
0 x 2 9 7 A 9 C 0 2 0 I
13, what is horizontal segmentation?
Horizontal segmentation is a technique that avoids the emergence of routing and accelerating routing agglomeration. Since the router may receive the routing information itself sent, this information is useless, and the horizontal segmentation technology does not reverse any route update information received from the terminal, but only the notice will not be cleared due to the count to endless. routing.
14. How is the routing ring produced?
Due to the existence of the network's routing aggregation time, the route of the new route or changes in the routing table cannot be stabilized quickly in the whole network, so that there is inconsistent route, so the routing ring will be generated.
15, what is a metric?
Metric representative distance. They are used to determine the optimal route when looking for routing. Each routing algorithm is generated when a routing table generates a value (metric), and the minimum value represents the optimal path. The calculation of the metric can only consider a characteristic of the path, but more complex metrics is generated by a plurality of features that integrate the path. Some common metrics are:
◎ Skumper number: The number of router output ports to be passed.
◎ Ticks: Delay of the data link (approximately 1/18 per second).
◎ The cost: It can be an arbitrary value, which is obtained according to the calculation method defined by the bandwidth, cost or other network managers.
◎ Bandwidth: The capacity of the data link.
◎ Delay: The length of the message transmitted from the source to the destination.
◎ Load: The size of the part of the network resource or link has been used.
◎ Reliability: The ratio of the error bits of the network link.
◎ Maximum Transmission Unit (MTU): All links accepted on a path (unit are bytes).
What type of route metric is used by IGRP? What make up this measure value?
IGRP uses multiple routing metrics. It includes the following sections:
◎ Bandwidth: Source to the smallest bandwidth value between the destination.
◎ Delay: The interface delay accumulated in the path.
◎ Reliability: The worst possible reliability between the source to the purpose, based on the state of the link.
◎ Load: The link between the destination is in the worst case load, expressed by bits per second.
◎ MTU: The minimum M t u value in the path.
16, can the metrics can be modified or adjusted?
Add a positive offset. The integrity of this command is as follows: You can use the Offset-List Router subcommand to add a positive offset to the network input and output metrics in the access table.
Offset-list {in | out} offset [access-list] no offset-list {in | OUT} offset [access-lis]
If the value of the parameter List is 0, the OFFSET parameter will be added to all metric. If the value of Offset is 0, there is no effect. For IGRP, the value of the offset is only extension. This subcommand also applies to RIP and Hello routing protocols.
Use the no offset- list command with appropriate parameters to clear this offset.
In the following example, a router using IGRP adds an offset 10: Offset-List Out 10 at the time of all output metric
Below is an example of adding the same offset to access table 121:
Offset-list Out 10 121
17. Which five parties do you need to know when you look for routing?
All routers need to find routing as the following information:
◎ Destination address: the destination host sent by the message.
◎ Determination of the neighboring station: Indicates who is directly connected to the router interface.
◎ Route discovery: find which networks know the neighborhood.
◎ Select routing: Provide the optimal path to the destination (related to metric) by information from the neighboring station.
◎ Keep routing information: The router saves a routing table, which stores all the routing information you know.
18. Is the routing protocol supported by the Cisco Router compatible with other manufacturers of equipment?
All routing protocols supported by Cisco routers are compatible with all routing protocols supported by IGRP and EIGRP. IGRP and EIGRP are patented products for Cisco.
19. What is the information about the entry of the RIP routing table?
Each of the entries for the RIP routing table provides certain information, including the final destination address, to the next hop address and metric of the destination. This metric represents the distance of the destination terminal (number of hops). Other information can also be included.
Router problem complement:
1. Does the Cisco3600 Series Router currently support WAN interface cards WIC-2T and WIC-2A / S?
The Cisco3600 Series Router supports both WIC-2T and WIC-2A / S in two wide area network interface cards in 12.007xK and above.
But you need to pay attention to:
Only fast Ethernet hybrid network modules can support these two wide area network interface cards.
The network module supporting these two interface cards is as follows:
NM-1FE2W, NM-2FE2W, NM-1FE1R2W, NM-2W.
The Ethernet hybrid network module does not support, as shown below:
NM-1E2W, NM-2E2W, NM1E1R2W.
2, the NM (4A / S, NM (8A / S network module and WIC (2A / S wide-area network interface card support support by the Cisco3600 series router?
These network modules and wide area network interface cards can support asynchronous and can also support synchronization. The maximum asynchronous rate supported is 115.2kbps, and the maximum synchronization rate is 128kbps.
3, which is the cable of WIC-2T and WIC-1T?
Wic-1T: DB60 turn V35 or RS232, 449 and other cables. Such as: CAB-V35-MT.
WIC-2T: Smart type V35 or RS232, 449 and other cables. Such as: CAB-SS-V35-MT.
4, what is the difference between MCE1 and CISCO 2600/3600 on the Cisco 7000 Series?
The MCE1 on the Cisco 7000 can be configured as E1, CE1, while the CI1, CE1 on the Cisco 2600/3600 supports only its own functions. 5. Is the Cisco 2600 Series Router Supporting VLANs, what is the need for iOS software?
Cisco (2600 Series Router, only Cisco2620 and Cisco2621 can support routing between VLANs (100M ports support VLAN routing). And if the VLAN route is supported, IOS software must include IP Plus feature sets.
6. Is there a difference in hardware than 3620/3640 routers?
Different points are as follows:
* Cisco3660 router Basic configuration includes 1 or 2 10 / 100M adaptive fast Ethernet interface; the Cisco3620 / 3640 basically does not include an Ethernet interface.
* Cisco3660 router supports hot-swappable network modules, while Cisco3620 / 3640 does not support hot-swappable network modules.
* The redundant power supply of Cisco3660 is built-in, and the redundant power supply of Cisco3620 / 3640 is external.
7. Why can't 3640 not recognize NM-1FE2W?
Need to upgrade iOS to 12.0.7T
Switch problem
About switch issues:
1, how is the stack of Catalyst 35500XL / 2950XL?
a. Need to use a special stack cable, 1 meter long or 50 cm long (CAB-GS-1M or CAB-GS-50CM) and special Gigabit stacked card GigaStack GBIC (WS-X3550-XL) (the card has included CAB-GS-50CM stacked cable).
b. You can use two stacking methods: chrysanthemum chain method (providing 1G bandwidth) or point-to-point method (2G bandwidth).
c. 2 methods can be backed up.
d. Chrysanthemum chain method can support up to 9 switches, point-to-point method can support up to 8 sets.
2. Does the Catalyst 3550 XL Series Switches Do you support redundant backups?
There are two implementation methods for the Stack of Catalyst3550XL Series Switches: Chrysanthemum Chain Ways and Points.
When using a chrysanthemum, the stacked switches are sequentially connected, and the switches can reach the transfer bandwidth of 1Gbps;
When using a point-to-point approach, a separate Catalyst3508G-XL switch is required.
The remaining switches are connected to 3508g by stacking GBIC cards and stacked cables, which can reach the full-duplex transmission bandwidth of 2Gbps.
Both methods support stacking redundant connections, respectively. When using a chrysanthemum chain connection, the redundant connection is done by connecting the top switches with the lowermost switch to the stacked cable. When using a point-to-point connection, it is done by using the 2nd 3508 switch.
4, Catalyst3550 XL's Gigabit uses a stacked card to make a stack, can another Gigabit can connect Gigabit switches or Gigabit servers?
can. 1000BASE-SX GBIC or 1000BASE-LX / LH GBIC is required.
5, Ethernet Channel Tech. Can I apply between network devices? how to use?
Can be applied between switches, switches and routers, between switches and servers
2 or 4 10/100 Mbps or 1000 Mbps ports can be used using Ethernet Channel Tech. With a bandwidth of up to 400M (10 / 100Mbps port), 4G (1000Mbps port), 800M (10 / 100Mbps port), 8G (1000Mbps port) .
6. What is the effect of Ethernet CHANNEL TECHNOLOGY?
Increase bandwidth, load balancing, line backup
7. How to choose a line when the port is set to Ethernet CHANNEL?
Depending on which link output is determined from the last 1 or 2 position of the Ethernet address and destination address of the data frame. For the router, it is done or operates according to the network address to determine the output of the link.
8. The difference between Ethernet CHANNEL TECHNOLOGY and PAGP (Port AggRegation Protocol)?
PAGP is the enhancement version of Ethernet Channel, which supports Spanning Tree Protocol and UPLink Fast on Ethernet Channel and supports the bundle of automatic Ethernet Channel.
Local number of power supplies 1 2
Package transfer rate 18MPPS 18MPPS
Backplane bandwidth 24Gbps 60Gbps
9. Does the Catalyst4000 Series support ISL?
Start support from Supervisor Engine Software Release 5.1.
10. What is the difference between the redundant power options 4008/2 and 4008/3 of the Catalyst4000 switch?
There are two power slots on the Catalyst4003 switch chassis. It is self-contained in the factory, and 4008/2 is a redundant power supply for its customized. There are three power slots on the chassis of Catalyst4006, and 2 power supply is shipped at the factory, and 4008/3 is a dedicated redundant power supply for its customized.
11. Is the three-layer switching module of Catalyst 4006 not contain Ethernet ports?
No, the Catalyst4006's three-layer switching module contains 32 10/100 adaptive ports and 2 Gigabit ports. The original WS-X4232-GB-RJ module can be replaced when used on 4003 so as not to affect the network structure.
12. How to use the two exchange modules currently existing when the Catalyst 4000 Series Modular Switch uses a Gigabit switch module (the product number is as follows)?
WS-X4306-GB Catalyst 4000 Gigabit Ethernet Module, 6-Ports (GBIC)
WS-X4418-GB Catalyst 4000 GE Module, Server Switching 18-Ports (GBIC)
The use environment of these two modules is different
WS-X4306-GB is a 6-port Gigabit switch module, each port exclusive bandwidth, is suitable for the backbone of the network, used to connect a switch with Gigabit interface; or connected to the Gigabit network card .
WS-X4418-GB is a 18-port Gigabit switch module, two of which are exclusive gigabit bandwidth, and the other 16 ports share 8G full-duplex bandwidth, but each port can suddenly go to Gigabit . This module is suitable for connecting Gigabit servers in places where the server is concentrated, and is not suitable for connecting the network trunk.
13. How much is the backplane bandwidth and packet transfer rate of the Catalyst 6000 series?
The backplane bandwidth of the Catalyst 6500 series can be extended to 256Gbps, and the inclination rate can be extended to 150MPPS; the Catalyst 6000 Series can provide a cost-effective solution to the 32Gbps backplane bandwidth and 15MPPS package transition rate.
14. How much M DRAM is required for the MSFC of the Catalyst 6000 Series?
Catalyst 6000 Series iOS Software is stored in MSFC, and MSFC requires 128M DRAM. The default configuration has 128M DRAM.
15. Is there a restriction on the slot on the Catalyst 6000 series?
In addition to the first slot for the engine, the second slot can be used for backup engines or line cards, and other slots are used for line cards.
16. How many engines do the Catalyst 6000 Series?
The Catalyst 6000 Series is divided into two kinds of Supervisor Engine 1 and Supervisor Engine 1a, where Supervisor Engine 1A has two specific backup engines. Its models are as follows: Model Description WS-X6K-Sup1-2GE Catalyst 6000 Supervisor Engine1 Engine Contains two Gigabit ports (need purchase GBIC)
WS-X6K-SUP1A-2GE Catalyst 6000 Supervisor Engine1A Engine enhanced QoS features, including two gigabits (need to purchase GBIC)
WS-X6K-SUP1A-PFC Catalyst 6000 Supervisor Engine1A The engine contains two Gigabit ports (requires GBIC) and PFC cards
WS-X6K-S1A-PFC / 2 Catalyst 6000 Supervisor Engine1A redundant engine contains two Gigabit ports (requires GBIC) and PFC cards
WS-X6K-SUP1A-MSFC Catalyst 6000 Supervisor Engine1A The engine contains two Gigabit ports (requires GBIC) and MSFC, PFC cards
WS-X6K-S1A-MSFC / 2 Catalyst 6000 Supervisor Engine1a redundant engine, including two Gigabit ports (requires GBIC) and MSFC, PFC card
17. Is the backup engine and the main engine on the Catalyst 6000 series must be consistent?
Yes it is. The Catalyst 6000 series backup engine must be consistent with the main engine.
For example, the engine without MSFC & PFC can be prepared for engines with MSFC & PFC.
In addition, WS-X6K-SUP1A-PFC and WS-X6k-Sup1a-MSFC have a special backup engine.
The correspondence between the main and standby engines is as follows:
Main engine backup engine
WS-X6K-SUP1-2GE WS-X6K-SUP1-2GE
WS-X6K-SUP1A-2GE WS-X6K-SUP1A-2GE
WS-X6K-SUP1A-PFC WS-X6K-S1A-PFC / 2
WS-X6K-SUP1A-MSFC WS-X6K-S1A-MSFC / 2
18. What are the routing protocols supported by the Catalyst 6000 Series?
The Catalyst 6000 Series supported routing protocols are: OSPF, IGRP, EIGRP, BGP4, IS-IS, RIP, and RIP II;
Two modes of multicast PIM support sparse and DENSE;
Supported non-IP routing protocols include: NLSP, IPX RIP / SAP, IPX EIGRP, RTMP, Apple Talk EIGRP, and DECNET PHASE IV and V.
19. What are the network protocols supported by the Catalyst 6000 Series?
The 6MPPS IP, IP Masterning, and IPX are supported on the MSM. The MSFC on the engine supports 15MPPS IP, IP multicast, IPX, and AppleTalk, Vines, Decnet.
20, if the engine is SUP-1A-2GE, how to implement three-layer exchange function?
Implement with MSM. Only an engine containing MSFC can be implemented through MSFC, and MSFC cannot be ordered separately on 6000.
21. What is the difference between Catalyst? 6000 switches and Catalyst? 6500 switch? Can the 6000 switch upgrade to 6500 switches?
The backplane bandwidth of the Catalyst? 6000 series of switches is 32g, while the backplane bandwidth of the 6500 series switches can be extended to 256G. Since the backplane bus structure used by these two series of switches is different, the 6000 switch cannot be upgraded to the 6500 series switches. But these two series switches use the same exchange module.
22. Can Catalyst3508g can also use chrysanthemum chain stacking mode as Catalyst3524?
absolutely okay.
23. When configuring UPLINK-FAST between the switches, do you need to close the original spanning-tre option?
No need, UPLINK-FAST actually uses a simplified spanning-tree algorithm, compatible with standard spanning-trees, so there is no need to close this feature
