8
votes
Accepted
When X.25 or ATM were used in ISP networks or Internet backbone was the protocol running over this layer still TCP/IP?
Think of it this way: we used the fastest links we could buy to run IP over the wide area between the nodes of the Internet. So that was 56/48Kbps X.25, and later 1.44/2Mbps Frame Relay, and later ...
- 1,171
6
votes
Accepted
What are the reasons for ADSL to use ATM instead of Ethernet
According to the German Wikipedia the bit rates used in the time when ADSL was invented was the reason:
At that time the backbones of the telephone and internet providers operated at 1-40 MBit/s ...
- 2,346
4
votes
Accepted
Why are Frame Relay, ATM and MPLS called "Layer-2 VPN"?
Anything which joins a layer 2 network to another through a shared medium could be considered a layer 2 VPN.
Consider an office building where I rent rooms 1 and 101 and you rent 2 and 102. The ...
- 16.1k
4
votes
Accepted
WAN lines types - understanding leased line/circuit
A real leased line, could be performed with TDM on a line with for example SDH, TDH or SONET with a CSU/DSU on the customer site (a layer 1 leased line?)
This depends - usually a (rare) leased ...
- 81.5k
4
votes
Accepted
What's the difference of TR-069 and Point-To-Point protocol?
I think you are confused with the terms Point to Point and TR-069 here.
An ISP normally uses IPOE/PPPOE/PPPOA for establishing the connectivity between CPE(Modem/Gateway) and their BRAS. They also ...
- 1,412
4
votes
How did ATM switches that were implemented in a core of IP network improve QoS and higher data rate?
ATM (which is all but obsolete today) provided classes of service that guaranteed bandwidth resources. That feature has been replaced by classes of service in IP (using DSCP markings) that can be ...
- 66.9k
3
votes
What are the reasons for ADSL to use ATM instead of Ethernet
When ADSL came up in the late 1990s, Carrier Ethernet was in the far future - Ethernet was just 100 Mbit/s back then.
Then, carrier networks were SDH and used ATM as base protocol. This has changed ...
- 81.5k
2
votes
Is ATM a Wide Area Network?
ATM is a layer-2 protocol. Yes, it is (was?) mostly used in WAN deployments. However, there were PCI network cards to add ATM links to a PC/server. (3com 3c975, comes to mind)
When you purchase a ...
- 31.5k
2
votes
Where are ATM switches located in real life?
DSLAMs are usually placed as close as practical to the CPE -- because it's distance constrained. So they can be in someone's yard, hanging on a pole, buried in a vault (CEV), or in a nearby CO. The ...
- 31.5k
2
votes
Do X.25/Frame Relay/ATM/MPLS have their own switches?
There were, in fact, dedicated X.25 hardware switches produced by the likes of BBN (and others) in the late 70's and into the 80's. Pictures of this sort of thing would be the domain of various ...
- 6,104
2
votes
packet-switching, circuit-switching, PVC and SVC
Please help me to clarify if PVC and SVC can be either packet-switched
or circuit-switched or if PVC and SVC are always circuit-switched and
circuit-switching is a form of packet-switching?
It is ...
- 66.9k
1
vote
How did ATM switches that were implemented in a core of IP network improve QoS and higher data rate?
It's important to understand that ATM is a technology from the telco world, not from the IP world.
ATM was a technology created by the telcos with the aim of creating a "broadband integrated ...
- 13k
1
vote
Do X.25/Frame Relay/ATM/MPLS have their own switches?
Historically, Frame and ATM used purpose built devices. X.25 is a bit before my time, so I don't know if anyone had hardware switches for it. Today, almost everything is done with "soft switch&...
- 31.5k
1
vote
Virtual Circuits in a narrow band network
Your question is extremely broad, possibly due to some mixup.
All forms of ISDN use circuit switching, so channel resources are allocated for the entire duration of a connection. The various ISDN ...
- 81.5k
1
vote
Accepted
X.25 packet formats
Crikey, this is going back a bit :)
P(S) and P(R) were the send and receive sequence numbers, used to handle transmit and receive windows (how many data packets at L3 could be outstanding in either ...
1
vote
PVC not Accepted by CISCO 878
You can show the maximum supported PVC's for a device by checking the output of show atm interface ATM0. I suspect you will be limited to 4 VC's with a maxiumum of 1024 VCI's per VPI. If this is the ...
- 1,307
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