Switches and routers What is the difference
Both devices are connected to the Internet, the main difference between them is that the switch occurs at the data link layer of the second network, and the third layer occurs in the router network layer. This distinction is the fundamental difference between the respective work of the two. The router may find the IP address of the next device, TCPIP protocol can handle, and the one we have said switch is a MAC address for addressing.
Switches are data distribution network, the router can assign an IP address to the network address assigned to you and can come at any time by address to find you.
An IP router can be assigned to multiple hosts to use at different times. Through the switch MAC address and identify the various hosts.
Switch is to achieve that through a cable Internet, but everyone online is each dial, each use their broadband, we each Internet has no effect, even if others download their own Internet has no effect, and all use the same switch the computers are in the same local area network. Routers than switch a virtual dial-up function, through the same router internet computers share a single broadband account access between all affect each other, such as a computer download, then on the same router other computers will be very significant feel the speed is very slow. Computer on the same router is also within a LAN.
First, the switch performance
1. backplane bandwidth: refers to the maximum amount of data throughput that can switch between the interface processor and a data bus or an interface card, it is an important indicator of the switch. A total switch backplane bandwidth flag data exchange capabilities, in bps.
Calculated: backplane bandwidth = number of ports * 2 * port rate
2. The packet forwarding rate (throughput): refers to the number without loss of data transferred per unit time packet, unit: pps (package per second).
Packet is composed of a data packet, each packet processing consumes resources. If the packet forwarding rate is too small, it will become a transmission bottleneck.
Packet forwarding rate is the number of 64byte packet forwarding unit time computed by reference.
In an example gigabit port, 64byte packet, together with the frame header and the gap 8byte 12byte a fixed overhead, the actual packet length 84byte, so a single port gigabit packet forwarding rate calculated as follows:
1000 000 000bps/8bit/(64+8+12)byte=1 488 095pps
Is generally considered gigabit port packet forwarding rate 1.488Mpps. For example, the switch 24 gigabit port, which is disposed over the packet forwarding rate 24 * 1.488Mpps = 35.71Mpps.
3.MAC Address Number: Number of MAC addresses in the MAC address table of the switch can be stored.
4.VLAN entry
VLAN is a separate broadcast domain, can effectively prevent broadcast storms. VLAN support is also an important parameter to measure the switch
5. The maximum number of stacked: refers to the maximum number of switches in the stack of stackable units that can be stacked.
Second, the main performance indicators of the router
1. Throughput: refers to the router packet forwarding capacity is an important indicator of the performance of the router. A certain number of ports of the router, the length of the port speed, the packet type and packet concerned. Throughput includes two aspects: the machine throughput and port throughput.
2. backplane capacity
A backplane physical channels between input and output ports of the router. Backplane capability of a router is performed by the internal structure of the router decision. Traditional router uses a shared backplane structure, high-performance router backplane structure is used interchangeably.
3. packet loss rate
Refers to a router in a stable continuous load, the number of missing data packets representing the ratio of transmitted packets. Packet loss rate is one of the performance indicators to measure the router when overworked.
4. concurrent connections
When users access the network, each open a WEB page will establish one or more IP connections, each connection is a session, the router can handle the maximum number of sessions is the maximum number of concurrent connections.
The maximum number of concurrent connections is a point to point connection of the router can be processed simultaneously, it reflects access control and connection status tracking capability of a router connected to multiple devices, this parameter directly affects the size of the router can support maximum information points.
The number of connections established per second: the number refers to the TCP / IP connection within the router unit of time can be established again.
6. Delay and Delay Jitter
First delay means a data packet entering the router bit into the last bit time interval of the output router. The packet length and related to the link rate. General requirements for delay and less 1518Byte IP packet is less than 1ms.
Jitter is defined as the time delay
Extension of change. Data services for less demanding jitter, jitter generally not as a measure of the high-speed router main technical indicators, but for video, voice and other real-time services, the indicator is very important.
7. frames back to back
It refers to the minimum frame interval that does not cause packet transmission up to the number of packets when packet loss. This index is used to cache the ability to test the router.
The main memory of the router in four types:
RAM,ROM,NVRAM,FLASHRAM
A.RAM: providing temporary storage of data, including routing information table, the ARP cache operation information and configuration file (running-config) and the like, to facilitate quick access CPU;
B.ROM: corresponding to the BIOS of the computer, for guiding the device to save the file, the system comprising POST code and system boot code is mainly used for system initialization. Usually save the IOS operating system backup.
C.NVRAM: router startup configuration file
D.FLASH: the equivalent of a hard disk, the main storage IOS operating system, you can upgrade IOS routers by rewriting the contents of memory.