wan technoloy and physical layer

[sarahr202]

Hi everybody

How is everyone?

R1-------ppp----------R2

1)R1 and R2 are connected via ppp. what kind of physical layer  we can  use i.e  T1 line, isdn line for ppp?

R1-------frame relay switch.

2)what kind of physcial layer technology we can use to connect our router to frame relay switch?

R1---------ATM switch.

3)What kind of physical layer technology we can use to connect our R1 to ATM switch?

R1--------x.25 switch

4)What kind of physical layer technology we can use to connect R1 to x.25 switch?

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Let say we have two sites  R1   ad R2. . we want to connect them using T1 line.  The issue is we are unable to get t1 line at both sites from same provider. We have service provider SP1 at R1 site  and SP2 at R2 site.

R1--------t1--(SP1)                                                      (Sp2)-----t1------R2

5)Can we still able to connect these two sites even though both ends of t1 line are provided by different service providers ?

thanks and have a nice weekend.

[smehrnia · Accepted solution]

Hi Sarah,

long time...

1) PPP is capable of operating across any DTE/DCE interface. the only absolute requirement imposed by PPP is the provision of a duplex circuit, either dedicated or switched, that can operate in either an asynchronous or synchronous bit-serial mode, transparent to PPP link layer frames. i.e. V.35, RS-232, T1 CSU/DSU.

there is also PPPoE (PPP over Ethernet) and PPPoFR (over Frame-relay)

2) Serial interfaces. V.35 , HSSI.

3) Fiber Optics or Copper wire (Coaxial, Twisted pair) using ATM interface module cards.

4) X.25 is a packet switched WAN network which uses DTE/DCE form of communication between its devices, so it must be using Serial interfaces to achieve this. with either X.25 encapsualtion or use of PAD.

5) T1 Lines give you a channelized 1.544 Mbps bandwidth link with Voice n Data capability, which can u simply use to connect to an IP network (internet) and get connected to the other site.

although, there is another type of link called leased lines, which u usually have to be on a same provider to work out.

Hope it Helps,

Soroush.

[sarahr202]

thanks Soroushm

Just got back from a long needed vacation.

[sarahr202]

R1-------frame relay switch.

2)what kind of physical layer technology we can use to connect our router to frame relay switch?

2) Serial interfaces. V.35 , HSSI.

How long this cable v.35 ,HSSI can be ? for example If the frame relay switch is 2 miles from our site. Are we going to use 2 mile v.35 or HSSI cable to connect it?

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T1 Lines give you a channelized 1.544 Mbps bandwidth link with Voice n  Data capability, which can u simply use to connect to an IP network  (internet) and get connected to the other site.

R1--T1---R2

There is no voip traffic. Both sites forward only packets using T1 line. If R1 receives Ip packets destined for R2( no Voip packets), Will R1 still use 24 or 23 channelized slots to forward those packets?

thanks and have a nice weekend.

[smehrnia · Accepted solution]

about Frame relay:

frame relay as you already know is a packet switching mechanism, we use those type of physcal layer connections to connect to a FR transmitter modem or sth in the local site, from local site to the FR service provider, connection happenes over other types of long range Media.

Actually we receive an End-to-End rrame relay service, but in the service provider cloud, it could be a MPLS network.

V.35 and other serial connections support only a couple of meters.

T1:

yes on the T1 controller you configure which channel slots to be used, each channel provides you with a ~64K bandwidth. the total bw would be sum of that.

Hope it Helps,

Soroush.

[sarahr202]

Thanks Soroush

Obviously, we can not stretch v.35 over 2 mile to connect to frame relay switch. So when we order frame relay connection from provider, how does provider terminate that connection at customer site? I mean what kind of connection? for e.g

site -R1-s0---cable 1-----------Demarcation point-------cable2------Frame relay switch

As you mentioned cable 1 could be v.35 cable, but what kind of cable is cable 2?

thanks and have a great weekend.

[smehrnia · Accepted solution]

could be ISDN, T-Carriers i.e. T1

HTH,

Soroush.

[paolo bevilacqua · Accepted solution]

Frame relay is a slow and largely outdated tehcnology, that should not be used for new designs.

You will get better perfrmances and smaller cost, with VPN, or check what are the alternatives.