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Networking/Discussion/Technology/Number of PPP instances on same serail port /List of Posts
Forum Topic - Number of PPP instances on same serail port : (4 Items)
   
Update
ravi varma
11/26/2008 9:53 AM
post17373
Number of PPP instances on same serail port   
Hi 

Till now i was with assumption that PPP is only between 2 systems, used only for point to pint communcaition, and one 
PPP instance will be connected to dedicated serial link.

But today i tried intantiating 2 processes on same serail port.I.e 

First i did

pppd /dev/ser2 proxyarp 115200 192.168.0.200:192.168.0.210
then i did 
pppd /dev/ser2 proxyarp 115200 192.168.0.200:192.168.0.220

and as part of ifconfig i got :

ppp1: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
        inet 192.168.0.200 -> 192.168.0.210 netmask 0xffffff00
ppp0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
        inet 192.168.0.200 -> 192.168.0.220 netmask 0xffffff00

when i tried to attach third instance 
pppd /dev/ser2 proxyarp 115200 192.168.0.200:192.168.0.230

ppp0: flags=8050<POINTOPOINT,RUNNING,MULTICAST> mtu 1500
ppp1: flags=8050<POINTOPOINT,RUNNING,MULTICAST> mtu 1500
ppp2: flags=8050<POINTOPOINT,RUNNING,MULTICAST> mtu 1500

all three got failed,

1. Is there any limit on no of virtual PPP interfaces that can be connected to a particaular serail link. 
2. what woud be real need for instantiating multiplte virtaul PPP interfaces, is it that if i have RS-485 is on other 
end of serail port, can i have a one to many network, where each virtaul instance can communiate with one device on 485 
network ? ... send me some links where i can get data on this.

Thanks
Ravi
Xiaodan Tang(deleted)
11/27/2008 7:53 PM
post17502
Re: Number of PPP instances on same serail port   
Attach multiple ppp instances on same serial does not sound right. Can you explain what exactly you are trying to do?
ravi varma
11/28/2008 3:42 AM
post17508
Re: Number of PPP instances on same serail port   
Hi 

Please see attached ppt. Aim is to directly send command from A to D1, D2, D3 on their IP Addresses, for this what we 
need to do in B.

1. If ppp is b/w two machines (B and C) then i used 
pppd /dev/ser2 proxyarp 115200 192.168.0.200:192.168.0.210 to assign Ip address to B and C, which comunicates over 
serail port.

2. From my understanding now C has to act as router, so initial thought that came to me is 
- To create as many ppp process for handling D1,D2,D3 etc ..in B and C, all of which will use the same serial port. 
- Since D1,D2,D3 will have already Ip assigned (ethernet port) C will act as router to forward the packets, i.e by 
enabling IP forward mechanism. 

But i am not sure the concept is goign to work or not. I am still trying, Let me know if i went wrong coceptually any 
where, suggest me any better approach.

Thanks
Ravi 




destiantion is only C then what we did is enable pppd


> Attach multiple ppp instances on same serial does not sound right. Can you 
> explain what exactly you are trying to do?
Attachment: Powerpoint ppp_router1.ppt 20.5 KB
Xiaodan Tang(deleted)
11/28/2008 5:38 AM
post17511
RE: Number of PPP instances on same serail port   
No, you should only establish one ppp connection between B and C.

Both B and C will acting as a router, make sure both of them have
forwarding enabled.

The rest is just to set everyone's routing table so A knows how to goto
D[1-3], and D{1-3] knows how to reach back to A.

-xtang

> -----Original Message-----
> From: ravi varma [mailto:community-noreply@qnx.com]
> Sent: November 28, 2008 3:43 AM
> To: technology-networking
> Subject: Re: Number of PPP instances on same serail port
> 
> Hi
> 
> Please see attached ppt. Aim is to directly send command from A to D1,
D2,
> D3 on their IP Addresses, for this what we need to do in B.
> 
> 1. If ppp is b/w two machines (B and C) then i used
> pppd /dev/ser2 proxyarp 115200 192.168.0.200:192.168.0.210 to assign
Ip
> address to B and C, which comunicates over serail port.
> 
> 2. From my understanding now C has to act as router, so initial
thought
> that came to me is
> - To create as many ppp process for handling D1,D2,D3 etc ..in B and
C,
> all of which will use the same serial port.
> - Since D1,D2,D3 will have already Ip assigned (ethernet port) C will
act
> as router to forward the packets, i.e by enabling IP forward
mechanism.
> 
> But i am not sure the concept is goign to work or not. I am still
trying,
> Let me know if i went wrong coceptually any where, suggest me any
better
> approach.
> 
> Thanks
> Ravi
> 
> 
> 
> 
> destiantion is only C then what we did is enable pppd
> 
> 
> > Attach multiple ppp instances on same serial does not sound right.
Can
> you
> > explain what exactly you are trying to do?
> 
> 
> 
> 
> _______________________________________________
> Technology
> http://community.qnx.com/sf/go/post17508

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