loose source record route option in ip header ,still puzzled

Answered Question
Apr 25th, 2010
User Badges:
  • Bronze, 100 points or more

I was reading  rfc 791 ( internet protocol)  .  I am still puzzled about  loose source record option


I will use en example to make my point.





let say we have a network as shown below.



H1---------e0R1s0--------------------------s0R2---------H2


Where  H  denotes host and  R  denotes router.


Let say  R1 receives the packet on e0 from H1, with Loose source record option with  ip1,ip2  listed in the route field.

pointer in the option points to to ip1,  R1  replaces the  ip address in the destination ip address field with ip1, increments the pointer by 4.


Here is my confusion,  according to rfc, R1 will replace the  ip1 with recorded route address in the option data field



According to rfc,  the recorded route address is the internet module's own internet address as known  in the enviroment into which this datagram is being forwarded.



It  all seems greek to me.



How will R1 replace the ip1 ?  will it replace it with ip address of e0 or  so?





thanks a lot.








http://http://www.rfc-archive.org/getrfc.php?rfc=791

Correct Answer by Ganesh Hariharan about 7 years 1 month ago

I was reading  rfc 791 ( internet protocol)  .  I am still puzzled about  loose source record option


I will use en example to make my point.





let say we have a network as shown below.



H1---------e0R1s0--------------------------s0R2---------H2


Where  H  denotes host and  R  denotes router.


Let say  R1 receives the packet on e0 from H1, with Loose source record option with  ip1,ip2  listed in the route field.

pointer in the option points to to ip1,  R1  replaces the  ip address in the destination ip address field with ip1, increments the pointer by 4.


Here is my confusion,  according to rfc, R1 will replace the  ip1 with recorded route address in the option data field



According to rfc,  the recorded route address is the internet module's own internet address as known  in the enviroment into which this datagram is being forwarded.



It  all seems greek to me.



How will R1 replace the ip1 ?  will it replace it with ip address of e0 or  so?





thanks a lot.


Hi,


Loose Source Routing is an IP option which can be used for address translation.Loose source routing uses a source routing option in IP to record the set of routers a packet must visit. The destination of the packet is replaced with the next router the packet must visit. By setting the forwarding agent (FA) to one of the routers that the packet must visit,


The name loose source routing comes from the fact that only part of the path is set in advance.This is in contrast with strict source routing, in which every step of the route is decided in advance when the packet is sent.


Check out the below link for example :-


http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f22.shtml


Hope to Help !!


Ganesh.H

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Correct Answer
Ganesh Hariharan Sun, 04/25/2010 - 23:37
User Badges:
  • Purple, 4500 points or more
  • Community Spotlight Award,

    Member's Choice, February 2016

I was reading  rfc 791 ( internet protocol)  .  I am still puzzled about  loose source record option


I will use en example to make my point.





let say we have a network as shown below.



H1---------e0R1s0--------------------------s0R2---------H2


Where  H  denotes host and  R  denotes router.


Let say  R1 receives the packet on e0 from H1, with Loose source record option with  ip1,ip2  listed in the route field.

pointer in the option points to to ip1,  R1  replaces the  ip address in the destination ip address field with ip1, increments the pointer by 4.


Here is my confusion,  according to rfc, R1 will replace the  ip1 with recorded route address in the option data field



According to rfc,  the recorded route address is the internet module's own internet address as known  in the enviroment into which this datagram is being forwarded.



It  all seems greek to me.



How will R1 replace the ip1 ?  will it replace it with ip address of e0 or  so?





thanks a lot.


Hi,


Loose Source Routing is an IP option which can be used for address translation.Loose source routing uses a source routing option in IP to record the set of routers a packet must visit. The destination of the packet is replaced with the next router the packet must visit. By setting the forwarding agent (FA) to one of the routers that the packet must visit,


The name loose source routing comes from the fact that only part of the path is set in advance.This is in contrast with strict source routing, in which every step of the route is decided in advance when the packet is sent.


Check out the below link for example :-


http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f22.shtml


Hope to Help !!


Ganesh.H

Actions

This Discussion