Switch_faq generali 2 eng - D-Link

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Oct 26, 2013 (3 years and 8 months ago)

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D
-
Link
Mediterraneo Technical Support



D
-
Link Mediterraneo Srl

Via Nino Bonnet, 6/B


20154 MILANO

Tel. 02
-
29000676 Fax 02
-
29001723

E
-
Mail: luciano.vanzu@dlink.it

E
-
Mail: gianluigi.vinante@dlink.it


FAQs for D
-
Link 10/100/1000Mbps Ethernet Switches




Date: 24 January 2000

Prepared by D
-
Link Technical Marketing


Release 1.2 Updated Information:

1.

Maximum number of VLANs for DES
-
3225G

2.

Port Trunking spec for DES
-
3624/3225G

3.

Backplane capacity of DES
-
3624

series

4.

No support for MAC
-
based VLAN

5.

Integrate previous versions of switch FAQs


In this FAQ, D
-
Link Switch Models Include:



DES
-
1016D (16
-
port 10/100Mbps desktop
-
sized unmanaged switch)



DES
-
1016R/1024R (16 or 24
-
port 10/100Mbps rack
-
mountable unmanaged s
witches)



DES
-
3225G (24
-
port 10/100Mbps plus 1 Gigabit port managed switch)



DES
-
3624 Series (includes DES
-
3624i and DES
-
3624, 24
-
port 10/100 stackable managed switches)



DGS
-
3204/3208F (4 or 8
-
port managed Gigabit switches)



Previous version of switch FAQ inc
luded: DES
-
802/818/1004/1008/2212/2218/ 2108/1012/5016,3216, DES
-
815/810/810E
and 2208



Product Overview

1. What are the differences between the DES
-
1016, DES
-
1016D and DES
-
1016R?

The ‘D’ in 1016D means “desktop,” and the ‘R’ in 1016R means “rack
-
mountabl
e.” Users can easily distinguish the
case size using the naming system of the 1016 switch series. Here are the major differences for these switches:

Feature
\

Model

DES
-
1016/1016F

DES
-
1016R

DES
-
1016D

Case size

Rack
-
mount, 1.25U

Rack
-
mount, 1U

Deskto
p

Port trunking & VLAN

Yes

No

No

Console port

Yes

No

No

100BaseFX module

Yes, DES
-
1016F

No

No


2. What does “switching” mean?


-

The concept and process are similar to Bridging, but with much lower latency.


-

Multi
-
conversation can be built simulta
neously.


-

Dedicated bandwidth for each port.


-

Wire
-
speed for packet filtering and forwarding processing.


-

Improved performance:



Aggregate bandwidth for simultaneous conversation



Consistent response times


-

Less or NO collisions.


-

Provides 100
Mbps capability while preserving any existing 10Mbps investment.


-

Extends the Class2 Fast Ethernet cascade distance from 5M to 100M.


-

Eliminates Class2 Fast Ethernet two repeater count limit issue.


3. How can you use a switch to protect your current

network investment?


A Switch can be installed up
-
stream from existing hubs, routers, and servers. It isn’t necessary to remove or replace
any existing equipment. In doing this, you will create dedicated bandwidth for each device at each port:


-

No N
IC change is necessary for stations or servers.


-

No cable or software driver changes are necessary anywhere.


4.When should you add a switch?


-

Poor network performance: high collision rates causing server access time outs.


-

Slow network response:
one conversation per collision domain at one time.


-

Can’t login to the network: bottlenecks caused by accommodation of bandwidth intensive applications.


-

Abnormal network disconnects: heavy traffic causing unpredictable response times and insufficien
t usable
bandwidth.




D
-
Link
Mediterraneo Technical Support



D
-
Link Mediterraneo Srl

Via Nino Bonnet, 6/B


20154 MILANO

Tel. 02
-
29000676 Fax 02
-
29001723

E
-
Mail: luciano.vanzu@dlink.it

E
-
Mail: gianluigi.vinante@dlink.it


5. “Routers vs. Switches”


Why are switches more popular for LAN segmentation now?


-

Cost effective.


-

Plug
-
and
-
play.


6. What are some significant benefits of switches?


-

Isolate local traffic.


-

Upgrade network performance t
hrough micro segmentation.


-

Provide high throughput for backbone interconnections.


-

Full Duplex data transmission for server connections.


7. After adding a switch, what new target applications could you then use?


-

Mass file transmit. (CAD/CAM and

multimedia)


-

Video Conference (Real time transfer)


8. What kinds of security do switches provide or support?


There are two ways to use a D
-
Link switch to improve network security:

-

VLAN
: A network administrator can define several VLANs and block ac
cess to each VLAN to prevent users from
accessing servers for which they don’t have access permission.

-

MAC Address Filtering
: A network administrator can define a DA (Destination Address) so that packets can only
be received from port A (a hub) and o
nly allow those same packets to be forwarded to port B(a server connection, for
example).Using MAC address filtering, only users that are connected to port A can access the server connected to
port B, other packets from other ports, even those whose DA is
for the server on port B, will be dropped.


9. What is the difference between “cut
-
through,” “store
-
and
-
forward,” and “fragment free cut
-
through”?

Cut
-
Through
: The switch will begin forwarding data after it receives the DA (destination address) of the fra
me, the
difference between this and store
-
and
-
forward is that store
-
and
-
forward receives the whole frame before
forwarding. Since frame errors cannot be detected by reading only the DA, cut
-
through may impact network
performance by forwarding corrupted o
r truncated frames. These “bad” frames can create broadcast storms
wherein several devices on the network respond to the corrupted frames simultaneously.

Store
-
and
-
Forward
: The switch will wait until the entire frame has arrived prior to forwarding it. T
his process
ensures that the destination network is not affected by corrupted or truncated frames, but is a slower method than
cut
-
through.

Fragment Free Cut
-
Through
: Somewhere halfway between cut
-
through and store
-
and
-
forward, fragment free cut
-
through on
ly forwards packets a minimum of 64 bytes long, and filters out packets shorter than 64 bytes, such as
corrupted or runt data. The difference between this method and store
-
and forward is that it will still forward
corrupted packets if they are longer than

64 bytes.


10. What are “crossbar,” “shared memory,” and “shared bus” architectures for in Ethernet switches?


Crossbar:
Based on a point
-
to
-
point or meshed matrix design, it establishes links between MAC addresses to setup
the connection before transmit
ting data. This architecture offers better performance, but is not very flexible.

Shared Memory:

Based on a serial
-
to
-
parallel MUX for each port input, only packet headers are sent to the control
unit, an entry packet is sent to shared memory for processi
ng. Then a parallel
-
to
-
serial DEMUX for packet
output to each port is used. This architecture provides low cost for ASIC logic, and gives the manufacturer more
flexibility in system design.

Shared Bus:
This architecture implements TDM (Time Division Mult
iplexing) technology, so each port has a turn
for transmitting its packets over a common bus. Because the time slot is fixed, performance can be carefully
controlled. This architecture provides good expandability, because the common bus is fixed, so desi
gners can
decide how many input ports and output ports will be provided.


11. Which architecture do D
-
Link switches use? Crossbar, Shared Memory, or Shared Bus?

We use all three architectures, implemented on different D
-
Link switch models. Since we know
the pros and cons
of these three architectures, we implement each of them to provide options for different applications.


12. How do D
-
Link switches implement path redundancy?

D
-
Link’s intelligent switches support the IEEE 802.1d Spanning Tree protocol, so

you can connect two paths to the
same destination. When the SPA is active, only one path is in use, others are back
-
ups which automatically take
over when the master is no longer active.





D
-
Link
Mediterraneo Technical Support



D
-
Link Mediterraneo Srl

Via Nino Bonnet, 6/B


20154 MILANO

Tel. 02
-
29000676 Fax 02
-
29001723

E
-
Mail: luciano.vanzu@dlink.it

E
-
Mail: gianluigi.vinante@dlink.it

13. What is a “stackable switch” and what are its advantages?


A s
tackable switch is a switch design which enables more than one switch to be stacked together using cascade
cables, instead of connecting with each other using TP cables through front panel ports.



14. What is the backplane speed of D
-
Link Switches? How ar
e they calculated?

The backplane speed is one factor used to judge the performance of a LAN switch. There are several kinds of
switching architecture, for example: shared bus and shared memory. Here are the backplane speeds for D
-
Link
switches, all of wh
ich use a shared bus architecture:



Shared
-
Bus Switches Backplane Speeds:


---------------------------------------------------



DES
-
802: 2 Gbps


DES
-
818/1004/1008/2212/2218/2108: 1 Gbps


DES
-
1012: 1.3 Gbps


DES
-
5016/3216
: 5 Gbps



Non
-
Bus
-
Type Switches Maximum Bandwidth Capabilities:


--------------------------------------------------------------------------



DES
-
815/810/810E: 560 Mbps


DES
-
2208: 900 Mbps



How are they calculated?

For example
, the DES
-
2208 was designed based on


the cross
-
bar switch architecture using D
-
Link's switch fabric controller IC


DL3550. This architecture provides wide bandwidth and low switching latency.



* The switch fabric (DL
-
3550) :


1. Pr
ovides 9x9 channels :


Nine (8 bit) input port channels and nine (8 bit) output port channels.


2. Switch frequency maximum is up to 33 MHz, but D
-
Link implements 12.5 MHz in


the DES
-
2208 system design.


3. So, the total band
width of the backplane of the DES
-
2208 is:


12.5Mhz * 8 bits * 9 channels = 900Mbits (@12.5Mhz system clock)


Feature Description

1.

Do the DES
-
1016D and DES
-
1016R support IEEE 802.3x Flow control?

Yes, both switch models support IEEE 802.3x flow

control in Full Duplex mode, and they support back pressure in
half
-
duplex mode to prevent network traffic congestion.


2.

Which switching architecture and packet forwarding method do D
-
Link switches support? What is the
maximum backplane capacity of D
-
Link
Switches?

Here is a list of D
-
Link switch backplane capacities, architectures, and forwarding methods:

Model

Max. Backplane
C
a
p
a
c
i
t
y

Architecture

Packet Forwarding

DES
-
1016D

4.8Gbps

Shared Memory

Store & Forward

DES
-
1016R

2.4Gbps

Shared Memory

Store & F
orward

DES
-
1024R

2.4Gbps

Shared Memory

Store & Forward

DES
-
3225G

Approx. 10.66Gbps

Crossbar

Store & Forward

DES
-
3624i

Approx. 21.32 Gbps

Crossbar

Store & Forward

DES
-
3624

Approx. 10.66 Gbps

Crossbar

Store & Forward




D
-
Link
Mediterraneo Technical Support



D
-
Link Mediterraneo Srl

Via Nino Bonnet, 6/B


20154 MILANO

Tel. 02
-
29000676 Fax 02
-
29001723

E
-
Mail: luciano.vanzu@dlink.it

E
-
Mail: gianluigi.vinante@dlink.it

DGS
-
3204

10.6Gbps

Crossbar bus

Store

& Forward

DGS
-
3208F

21.32Gbps

Crossbar bus

Store & Forward

Notes: backplane capacity is also known as “switching fabric capacity.”


3.

Do D
-
Link switches support IGMP snooping? Which models?

Yes, most of D
-
Link’s managed switches support IGMP snooping, in
cluding the DES
-
3225G, the DES
-
3624 series,
and the DGS
-
3208F.


4.

Do D
-
Link switches support web based management?

Yes, all D
-
Link managed switches support web based management. The switches include an embedded web server
in the device. The network adminis
trator can easily use a web browser to manage all D
-
Link managed switches,
including the DES
-
3225G, DES
-
3624, DGS
-
3204, and DGS
-
3208F.


5.

Do D
-
Link switches support port trunking?

Yes, all D
-
Link managed switches support port trunking, including the DES
-
322
5G, DES
-
3624, and DGS
-
3208F.


6.

How many trunk groups does the DES
-
3225G port trunking feature support?

The DES
-
3225G can support up to three trunk groups and each trunk group can use 2 to 8 ports as a trunk.



7.

Does the port trunking feature of the DES
-
3225G

and DES
-
3624 work with Cisco’s Fast EtherChannel?

Yes, the port trunking feature of the DES
-
3624 and DES
-
3225G works with Cisco’s Fast EtherChannel.


8.

Do D
-
Link switches support/use MT
-
RJ connectors? What is an MT
-
RJ connector?

Yes, many D
-
Link switches su
pport/use MT
-
RJ connectors, some option module(s) for the DES
-
3225G, and DES
-
3624.


The MT
-
RJ is a new fiber
-
optic system that offers economies in size and system costs.

Based on the proven MT
ferrule, the connector is designed to offer the same ease of
use as, and a form factor similar to, the RJ
-
45 modular
plug and jack.

The system includes transceivers, connectors, connecting hardware, and cable to provide a
comprehensive end
-
to
-
end solution for a network cabling infrastructure.

For more detailed MT
-
R
J information,
please visit the following web pages:

http://www.amp.com/fiberoptics/mtrt
-
faq.ht ml

http://www.amp.com/networking
/solarum/white
-
paper.html


9.

What’s the difference between MAC
-
based VLAN and 802.1Q VLAN? Does MAC
-
based VLAN support
overlappi ng VLANs? Does 802.1Q VLAN support overlapping VLANs? Do D
-
Link switches support MAC
-
based VLANs?

There are two major differen
ces between MAC
-
based and 802.1Q VLAN, the first point of difference is that MAC
-
based VLAN is configured using MAC addresses, but 802.1Q VLAN uses assigned tag addresses to distinguish
VLAN information. The second difference is that MAC
-
based VLAN is a t
raditional and proprietary
-
based VLAN,
so interoperability is a problem. On the other hand 802.1Q VLAN, is an industry standard
-
based VLAN, which
helps resolve any interoperability problems between different vendors of LAN switches.


MAC
-
based VLAN
does n
ot

support overlapping VLANs, each MAC address may only belong to one VLAN.
However, 802.1Q VLAN does support overlapping VLANs. Currently D
-
Link switches (including the DES
-
3624,
DES
-
3225G, DGS
-
3204, and DGS
-
3208F) do not support MAC
-
based VLAN.


10.

How ma
ny IEEE 802.1Q VLANs can users set in the DES
-
3624 or the DES
-
3225G?

The DES
-
3624 and DES
-
3225G each support a maximum of 96 VLANs. Available VLAN IDs range from 1 to
4094.


11.

All of D
-
Link’s 100Mbps ports are 10/100 NWay, is NWay a standard? What is NWay?

Yes, NWay (auto negotiation) is a standard defined by the IEEE 802.3u, 100Base
-
T Working Group for a mechanism
to adapt multi
-
speed network devices. Currently, the NWay mechanism is defined in clause 28 of the D5 draft of the
ANSI IEEE Standard 802.3 MAC

parameters, Physical Layer, Medium Attachment Units and Repeater for 100Mbps
operation. This draft has been approved by the IEEE 802.3 Working Group.


NWay is a mechanism that takes control of the cable when a connection is established to a network devic
e. NWay
detects the various modes that exist in the device on the other end of the wire, and advertises it own abilities to



D
-
Link
Mediterraneo Technical Support



D
-
Link Mediterraneo Srl

Via Nino Bonnet, 6/B


20154 MILANO

Tel. 02
-
29000676 Fax 02
-
29001723

E
-
Mail: luciano.vanzu@dlink.it

E
-
Mail: gianluigi.vinante@dlink.it

automatically configure the highest performance mode of interoperation.


NWay acts like a rotary switch that automatically switches

to the correct technology, such as 10BASE
-
T, 100BASE
-
TX, 100BASE
-
T4 or a corresponding full duplex mode. Once the highest performance common mode is
determined, NWay passes control of the cable to the appropriate technology and becomes transparent until
the
connection is broken.


NWay leverages the proven link function of 10BASE
-
T to provide robust operation over Category 3, 4, or 5
Unshielded Twisted Pair (UTP). The primary benefit of NWay is automatic connection of the highest performance
technology av
ailable without any intervention from a user or network administrator.


12. What is RMON and do D
-
Link switches support RMON?

RMON (Remote Monitoring) is a standard for traffic analysis and troubleshooting, particularly for switched
networks. It defines s
pecifications for monitoring network traffic above the MAC layer. Network administrators
can deploy standards
-
based diagnostic solutions for enterprise
-
wide traffic and support mission
-
critical, server
-
based
applications.


Yes, currently the DES
-
5016, DGS
-
3208F, DES
-
3624i, DES
-
3225G, and DES
-
3216 switches support RMON. D
-
Link switches support the following basic four RMON statistic counter groups: Segment Statistics, History, Alarms,
Events.


In the future, D
-
Link will implement RMON features in intellige
nt hubs and additional switches.



Application Setup

1. What is the maximum number of switches that can be stacked with the DES
-
3624?

If a customer uses an SIO(Serial I/O) stacking module, the DES
-
3624i can stack with 3 DES
-
3624 switches, so the
maximum is

four DES
-
3624 in a single stack. Another way to cascade DES
-
3624i is by using a two
-
port Gigabit
module in a DES
-
3624i, the maximum stack size in this configuration is eight switches. Or a customer can use one
DGS
-
3208F to cascade eight DES
-
3624 (slave
model) switches using a one
-
port Gigabit uplink module. One stack
would then have a maximum of nine switches (including one DGS
-
3208F).


2. Can users install the DES
-
1016D in a standard 19” rack ?

Yes, there are optional mounting brackets (DFE
-
700B) that a
llow the DES
-
1016D to be installed in a standard rack.


These long bracket ears make the DES
-
1016D rack
-
mountable for standard racks.


3. What is the default username and password for management access to the DES
-
3624i?

When you first login to the DES
-
3624
i, the default username and password is:

Username: admin

Password: admin

(Please note that the username and password are both case
-
sensitive.)


4. Is the cascade cable for the DES
-
3624 series hot
-
swappable?

Basically the answer is yes. It is possible to ch
ange the configuration of the cascade cable while the DES
-
3624 is in
a “power
-
on” state, but for the configuration change to take effect, the switch MUST be restarted.



5. What is MII? How can we use the MII interface of the DES
-
815,
-
2212,
-
2218, and
-
3
208?

MII stands for “Media
-
Independent Interface.” MII is an industry standard that allows users to attach transceivers
for other types of 100BASE
-
X media, such as 100BASE
-
FX (DFE
-
854) to 100BASE
-
TX devices. When
connecting the DFE
-
853 or
-
854 Ethernet t
ransceivers to D
-
Link switches, the PHY address setting needs to be 02h.
On the DIP switch this is




SW1

SW2

SW3

SW4

SW5



off

off

off

on

off


If connected to non
-
D
-
Link equipment, the PHY setting needs to be obtained from the manufacturer.


6.

My switch
(DES
-
1004/1008) does not support MII, how can I connect to a fiber optic line?




D
-
Link
Mediterraneo Technical Support



D
-
Link Mediterraneo Srl

Via Nino Bonnet, 6/B


20154 MILANO

Tel. 02
-
29000676 Fax 02
-
29001723

E
-
Mail: luciano.vanzu@dlink.it

E
-
Mail: gianluigi.vinante@dlink.it

You can use DFE
-
855 TX
-
to
-
FX converter. The charts and tables below provide more detail on how to use the
DFE
-
855. Regarding the DFE
-
855, the following is data concerning comm
unication mode and transmission
distances.









Mode

Device A

Device B

X

Y

Full
-
duplex

DTE (*)

DTE

100m

2000m

Half
-
duplex

DTE

DTE

X <=100, X+Y <=360

Half
-
duplex

Class I hub
(+)

DTE

X <=100, X+Y <=130

Half
-
duplex

Class II Hub (+)

DTE

X <=100, X+Y <=174







Mode

Device A

Device B

X

Y

Z

Full
-
duplex

DTE (*)

DTE

100m

2000m

100
m

Half
-
duplex

DTE

DTE

X<=100m, X+Y+Z <=286m, Z<= 100m


* DTE (Data Terminal Equipment): workstation, switch, router, or terminal device

+ Distances given above assume that if device A is a 100Base
-
TX hub, twisted pair cable from it to devices other than
the DFE
-
855 are 100 meters long.


Reference

1.

External Specification (S/W and H/W) of D
-
Link Switches.

2.

User’s Guides for D
-
Link Switches.

3.

The MT
-
RJ introduction is from the web site of AMP Incorporated.






End of file



Max. distance

Max. distance

Y meters

X meters

Device A

DFE
-
855

Device A

DFE
-
855

DFE
-
855

Device A

Device B

X meters

Y meters

Z meters

Device B Has no fiber optic port