Questions tagged [ppp]

For questions about Point-to-Point Protocol (PPP), a data link protocol typically used in establishing a direct connection between two nodes.

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Does PPP do broadcasting? [duplicate]

Let's consider the scenario below: Router 1 <---> Router 2 <---> Router 3 Routers 1 and 3 establish a link with router 2, then will Router 2 broadcast to the interface connected to routers ...
Darevil294's user avatar
3 votes
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103 views

Address Field In PPP Protocol

What is the actual use of the Address Field on PPP As I know, it is always set to 11111111 and this doesn't seem to have any purpose because we use ppp we dealing with the direct link communication
Darevil294's user avatar
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What is PPP and why does it not have a MAC address?

I just wanted clarification on what exactly PPP is and why it does not have a MAC address due to having seen that under a response to a question of how routers transverse packets to their destinations....
N.C.'s user avatar
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Running 2 or more applications PPP

I had a doubt regarding point-to-point protocol. Is it possible for a single PPP link to enable running of 2 or more simultaneous applications between two hosts? Thanks!
ikben's user avatar
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How PPPoE uses addressing to know destination Mac address?

Case.1 We know that when router connected via point to point(PPP) protocol then ARP isn't used to know the destination Mac address. Case.2 When two router connected via PPP as well as Ethernet which ...
S. M.'s user avatar
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What is the addressing problem of SLIP? [closed]

In the RFC1055 that describes SLIP, in the DEFICIENCIES section, there is a bullet named "addressing" which says: both computers in a SLIP link need to know each other's IP addresses for ...
YoavKlein's user avatar
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What is SLIP good for? [closed]

I read a bit about SLIP in few places, and from what I understand, the goal of this protocol is to allow the transfer (or encapsulation) of IP packets between hosts over a serial line. But I don't ...
YoavKlein's user avatar
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In PPTP, do encapsulated packets get further encapsulated in Ethernet frames?

I know that for PPP to travel in datalink layer 2 (ethernet) , the ppp frames need to get encapsulated in a ethernet frame , thus PPPoE. Is the same case for PPTP too?
Allan's user avatar
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What really a point to point connection means? [duplicate]

I know that point to point connection is used to directly connect between two nodes without any intermediate. But if we take in our world the internet(WAN) , let's say I want to achieve a point to ...
Allan's user avatar
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can two devices communicate without physical layer?

can 2 device communicate with each other without data going to physical layer? for example we just use protocol of data link layer that use MAC address , but transferring this frame data between 2 ...
johnny is here's user avatar
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3 answers
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Why does PPP need an underlying protocol?

The Point-to-Point Protocol is (at least according to Wikipedia) a Datalink Layer Protocol. I know that different use cases exist for it but on examining the image below from Wikipedia one can see ...
Martin Dallinger's user avatar
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What is the purpose of the Set-Link-Info message in PPTP? The RFC seems to contradict itself in regard to this message

A PPTP connection transports payload data by wrapping it into PPP and then sending it over a previously negotiated Enhanced GRE link. As per PPTP RFC, the following holds true: The encapsulated PPP ...
Mecki's user avatar
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Who initiates PPP Keepalives after PPPoE session is Established between Modem and BNG?

Hello Everyone, In case of DSL Modem , normally service providers employ PPPoE connection between Modem and BRAS (BNG). We all know that when Modem dials , it goes through PPPoE stages namely 1 ) PADI ...
Nabeel's user avatar
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IPCP removing default route when 2 available

I've been stuck on this one in my lab for a while. Any help is appreciated. Here's my CPE edge topology: https://i.stack.imgur.com/a1R6U.png Take the below scenario: I have 2 circuits coming in that I ...
jaaacck's user avatar
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How is the PPP protocol byte-oriented as well as bit-oriented?

Many articles consider PPP as byte-oriented, and others mention it as bit-oriented. +----------+----------+----------+----------+------------ | Flag | Address | Control | Protocol | ...
mmbs's user avatar
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PPP, Ethernet and PPPoE differences

Correct me if I'm wrong. So, Ethernet technology is being primarily used in LANs. And we use PPP in serial links. To carry IP datagram, we can use either layer 2 technology, such as Ethernet, or we ...
pedal's user avatar
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Worst-case efficiency of PPP escaping mechanism

Will transferring over PPP data stream containing only reserved bytes 0x7E, 0xFF, 0x03 reduce bandwidth by 50% because of escaping? Then it seems to be very stupid if not say moronic. Such poor ...
Mikhail Karakulov's user avatar
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221 views

PPTP encapsulation process

i am learning networking and vpn technologies now and i have some problems with understanding the whole PPTP encapsulation process. So i will write steps of PPTP encapsulation process (as i understand ...
violetapple's user avatar
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Is PPP a useful choice for fiber connections?

I was recently thinking about how I would go about connecting two separate buildings using optical fiber cables. This is mostly for understanding how this would be done to further my mental horizon, ...
Kritzefitz's user avatar
2 votes
0 answers
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How to adjust output queue length on Cisco IOS synchronous PPP (Dialer/Virtual-access) interfaces [duplicate]

I have a Cisco 3845 running IOS 15.3(3)XB12 which is accepting synchronous MLPPP calls from ISDN lines via a PRI. I want to reduce the size of the output queue on the router's PPP interfaces, but the ...
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Assigning static IP addresses to dialin PPP users on Cisco IOS

I have a Cisco router running IOS 15.3 serving as a dial-in PPP endpoint for a handful of modems. I am using local authentication and a local IP pool to hand out dynamic IP addresses to the callers; ...
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Why does PAP authentication not work in Packet tracer 7.2?

Note : Platform = Packet Tracer 7.2.1 for Linux 64 bit on Fedora 29. I configured two serial interfaces in packet tracer v7.2 for PAP authentication. While one of them has the status up/up, the ...
Somenath Sinha's user avatar
3 votes
1 answer
395 views

Why are the Address and Control fields constant in PPP protocol?

I saw that address and control fields are constant in PPP protocol. What is the need for even having a field that has constant value in it if we had not have this field then wouldn't it have saved ...
Natesh bhat's user avatar
2 votes
1 answer
796 views

How exactly does CHAP authentication work?

Let's assume that pppd returns following message: rcvd [CHAP Challenge id=0x1 <12345>, name = ""] and password is "test". What string should I use to calculate MD5 hash for CHAP Response? [...
Adam's user avatar
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What is a "rotary dialer" in the context of dialup connections?

Some friends and I have discussed setting up a PPP dialup Internet gateway (solely for private use) for fun/nostalgia purposes. I've been reading through the Linux-PPP Howto at TLDP (old, I know, but ...
Kurt Weber's user avatar
3 votes
1 answer
578 views

How do protocols like PPTP, L2TP work below IP level

I have been using these protocols without deep understand how everything works under the hood. I understand a process of tunneling as follows When we are using protocols like OpenVPN, IPSec, SSH ...
solderingiron's user avatar
2 votes
1 answer
435 views

PPP CHAP Authentication password requirement

What is the requirement for CHAP authentication on a PPP interface? I thought both routers had to have the same password defined, such as below. r1> username r2 password demo r2> username r1 ...
dcrearer's user avatar
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IPv6 in PPP - should be an Interface Identifier negotiated FOR both ends of a link? Clarification of RFC 5072 needed

I am trying to implement IPv6 in an existing VPN PPP software, but having hard time of understanding some of the RFC 5072 sections meaning. Namely, section 4.1. Assumption 1: PPP interfaces do not ...
Evengard's user avatar
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Why is L2TP based on PPP and not PPPoE?

I'm trying to grasp why L2TP is based on PPP. I thought PPP was a protocol for point-to-point situations where you don't have Ethernet. So why/how is L2TP using PPP in order to establish communication ...
rigor's user avatar
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What does State PADISNT mean/stand for? (in CiscoRouter# show pppoe session)

I stumbled upon this while doing Person VUE Test Prep for CCNA and I came up with a question that google wasn't that helpful for. (This is just for curiosity, so a basic answer will do, but for others ...
neoakris's user avatar
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1 answer
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How to decipher, why the pppoe interface has disconnected?

I am using a Ubiquity Edgerouter X, which is connected to a Draytek modem. This is the log from the pppoe interface: #######@ubnt:~$ show interfaces pppoe pppoe0 log Tue Jun 13 06:26:00 IST 2017: PPP ...
noelmcg's user avatar
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2 answers
563 views

What is PPPOE line protocol?

In serial wan connection we use PPP or HDLC line protocols,but where would we use PPPOE? What is Ethernet in this term 'PPPOE'?
Tehmas's user avatar
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1 answer
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Where the password is stored when using ppp protocol

The question might sound dumb, but you never learn if you do not ask. When using PPP as a datalink layer, it offers you authentication by using username and password. Where is the username and ...
Ahmad's user avatar
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3 votes
2 answers
732 views

How is the length of a PPP frame known?

How does the receiver determine the length of a PPP frame (not PPPoE or PPPoA)? Structure of a PPP frame shows no length field. Sure, at the end of the frame there is a 2-byte checksum followed by a ...
Isabell Cowan's user avatar
0 votes
1 answer
978 views

IPCP DNS : Configure-Reject [closed]

I'm working with a VxWorks PPP server running on an embedded system. There seems to be a problem with IPCP DNS negotiation. Each time the PPP server offers a IPCP to a client, the client seems to be ...
fastforward's user avatar
3 votes
1 answer
2k views

PPP, VPN, Tunneling and OSI model

I am really confused about tunneling protocol family and all related protocols. I read a bunch of articles, rfc but still cannot get the idea. I will put my questions between my explanation. A ...
brqgddez's user avatar
0 votes
1 answer
249 views

PPP sessions on packet return?

Here is a picture of a an xDSL deployment : The BRAS is the termination for PPP sessions. The customer modem establishes a session with the BRAS, gets authenticated and can then access the ISP's ...
pHeoz's user avatar
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3 answers
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Configuring PPPoE client through OMCI on Huawei ma5608T

We've received an OLT ma5608T and an ONT hg8245H for a short period of time - we want to see if Huawei is better than Zhone. We don't have a full documentation for this OLT because we're not a partner ...
Tomasz Kasperczyk's user avatar
3 votes
2 answers
5k views

Why are /30 subnet used for PPP connections?

Our telephone company has recently set us up a new ADSL connection. It consists of a PPP link over ATM. The connection comes with a public /30 subnet that we can use to our liking. We used one of the ...
rrrrrrrrrrrrrrrr's user avatar
1 vote
1 answer
88 views

PPP compression and encryption: which one happens first?

If PPP is enabled for both compression and encryption, which one happens first, compression or encryption, before the PPP sends the data over the physical link?
R__raki__'s user avatar
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1 answer
449 views

Why PPP cares about network layer?

Why PPP have protocol field? Isn't whole purpose of partitioning communication system to have simple isolated subsystems?
Mr. Vader's user avatar
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2 answers
2k views

Link layer protocols used by ISP?

Newbie networking question here... Do ISPs generally use the same link layer protocols (Ethernet, ARP to relate to network layer 3, etc.) that are used on LANs? In school I learned in some detail ...
Adam Sharpe's user avatar
1 vote
2 answers
106 views

Is PPP used to connect immediately adjacent hosts on a network?

I know PPP is used for point-to-point connections. The Wikipedia article for "point-to-point" says that the term is used to refer to a wire that links only two computers or networks, as opposed to, ...
Zen Hacker's user avatar
1 vote
1 answer
606 views

What is happening during CHAP PPP authentication between Cisco routers?

I'm going through the great CBT nuggets series for the CCNA. In the video on WAN protocols Jeremy sets up a PPP connection between two routers using CHAP authentication. On each router he adds a ...
red888's user avatar
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2 votes
1 answer
88 views

Can I assign a ppp serial link to a subnetwork that is also being used?

Let's say a network admin is provided a /24 IP address and asked to create a network that involves two different subnetworks that are distant to each other. I have learned that I need to assign a ...
Onur's user avatar
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10 votes
2 answers
16k views

Why PPTP, L2TP, PPPOE are in OSI Layer2?

PPTP, L2TP, PPPOE - these are tunneling protocols. And they are Data link Layer protocols. Why? As I understood, Layer2 protocols work only in same subnet. They don't use IP addresses and cannot be ...
Алдар's user avatar
1 vote
1 answer
5k views

How does PPPOE bridging work?

How does the authentication take place in a pppoe bridge setup assuming I have a bridge modem and a router that is capable of maintaining a bridge connection both connected to an un-managed switch? ...
Craig Lafferty's user avatar
4 votes
1 answer
1k views

Will an ERICSSON T720G GPON ONU & a Linux box work as an upstream PPPoE BRAS in our demo setup?

I am a volunteer teacher trying to get my students fired up by learning Broadband. Accordingly I am building a small scale DSL/PPPoE Broadband network that they can touch, deconstruct and put back ...
Nick Mitchell's user avatar
2 votes
2 answers
356 views

Line Sync when there is supposed to be no ADSL codes on the line? [closed]

I have a client who had ADSL (1500/256), and in an attempt to get her a faster connection, she tried to churn to a different provider. Long story short, the other provider will not supply adsl ...
Reece's user avatar
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10 votes
1 answer
5k views

PPPoA ADSL Configuration with external modem on Cisco 891

Context We use Cisco 891 routers as CPE for several client sites. They are all running IOS 15. Cisco IOS Software, C890 Software (C890-UNIVERSALK9-M), Version 15.0(1)M8, RELEASE SOFTWARE (fc1) The ...
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