few questions about standard based hdlc,ppp

Answered Question
Aug 19th, 2009

Hi every body

I have few questions.

1) Will standard-based hdlc also use keepalive messages like cisco's hdlc ?

2) multilink support in ppp

My book says if a router has two parallel ppp links, then multilink ppp features will cause the router to segment the packets into two equal length frames then send on one link then send other one on the other ppp link.

How about if router has 4 ppp links, will router segment the packet into 4 small frames as well?

3)LQM feature

When router is configured for LQM,, lcp at each end of the link sends messages describing the numbers of correctly received packets and bytes. The router then compares this number of in-error frames to the number of frames and bytes it sent and it then calculates percentage loss. the router can take down the link after a configured error rate has been exceeded.

My questions is how about router calculated packet loss does not exceed the configured error rate,rather it is just equal to configured error rate. Will router still bring the link down?

Lcp sends messages desribing the numbers of correctly received packets and bytes .

How often this message is exchanged ?

thanks

I have this problem too.
0 votes
Correct Answer by Edison Ortiz about 7 years 3 months ago

Sarah,

1)

The standard HDLC based on IBM's SDLC protocol does not have keep-alive messages. The original type of transfer mode was NRM (Normal Response Mode) but this was replaced later by ARM (Asynchronous Response Mode) as the former only provided half-duplex communication while the latter provided full-duplex.

Keep-alive was introduced with Cisco's HDLC as an extension called SLARP (Serial Line Address Resolution Protocol).

2)

Yes

3) I suggest reading http://www.ietf.org/rfc/rfc1548.txt

HTH,

__

Edison.

Correct Answer by Lucien Avramov about 7 years 3 months ago

1) what do you mean by standard-based hdlc, what RFC are you referring to?

2) if 4 interfaces are in your multilink bundle, yes.

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Lucien Avramov Wed, 08/19/2009 - 16:00

1) what do you mean by standard-based hdlc, what RFC are you referring to?

2) if 4 interfaces are in your multilink bundle, yes.

Correct Answer
Lucien Avramov Wed, 08/19/2009 - 16:01

1) what do you mean by standard-based hdlc, what RFC are you referring to?

2) if 4 interfaces are in your multilink bundle, yes.

Correct Answer
Edison Ortiz Wed, 08/19/2009 - 16:26

Sarah,

1)

The standard HDLC based on IBM's SDLC protocol does not have keep-alive messages. The original type of transfer mode was NRM (Normal Response Mode) but this was replaced later by ARM (Asynchronous Response Mode) as the former only provided half-duplex communication while the latter provided full-duplex.

Keep-alive was introduced with Cisco's HDLC as an extension called SLARP (Serial Line Address Resolution Protocol).

2)

Yes

3) I suggest reading http://www.ietf.org/rfc/rfc1548.txt

HTH,

__

Edison.

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