routing issue

Unanswered Question
Jan 16th, 2007
User Badges:
  • Silver, 250 points or more

RTRA(eigrp)-RTRB(a0)-RTRC(a0+a66)-RTRD(a66)

|

|

RTR E


All the routers are conncected using serial links.


RTR A is running Eigrp and RTRB, RTR C and RTR D are running ospf.


10.0.0.0 /8 network is used on RTR A and RTR E whereas 172.0.0.0 /8 is used on the remaining Routers.


I am trying for redundency in this scenario.

My problem is,


172.29.140.0 / 25 network is allocated to RTR D.172.29.140.25 is allocated to ATM machine.


RTR E is the backup for this ATM machine( VSAT connectivity).


Whenever serial link b/n RTR C and RTR D goes down , then traffic should take path through RTR E.(i.e RTR A to RTR E to reach ATM on VSAT link).


I have configured the following routes on RTR A which is running Eigrp.


ip route 172.29.140.25 255.255.255.255 172.16.17.121

ip route 172.29.140.25 255.255.255.255 10.30.0.126 120.


Where 172.16.17.121 is serial ip of RTR B and 10.30.0.126 is serial ip of RTR E.


As soon as I shutdown the serial link of RTR C which is connecting to RTR D , we are getting ospf updates till RTR B.Where as the static route configured on the RTR A is not purging out from RTR A route table so that floating static route will come in to picture.


static routes are redistibuted on RTR A and RTR B under Eigrp (RTR A) and OSPF (RTR B).


Whenever I shutdown serila link of RTR C , ospf updates on RTR B , RTR C are not showing 172.29.140.0 subnet and static route on RTR A is still pointing towards RTR B not to RTR E.

But as soon as i shut the serial interface of RTR C , the static on RTR A is not vanishing from routing table of RTR A.


The ouptut taken on RTR A and RTR B without shutting down the serail link of RTR C are.


RTR A#sh ip route 172.29.140.25

Routing entry for 172.29.140.0/25

Known via "static", distance 1, metric 0 (connected)

Redistributing via eigrp 15

Advertised by eigrp 15

Routing Descriptor Blocks:

* 172.16.17.121

Route metric is 0, traffic share count is 1


and

RTR B#sh ip route 172.29.140.25

Routing entry for 172.29.140.0/25

Known via "ospf 192", distance 110, metric 1954, type inter area

Redistributing via rip

Advertised by rip metric 10

Last update from 172.16.0.5 on GigabitEthernet5/2, 00:00:31 ago

Routing Descriptor Blocks:

* 172.16.0.5, from 192.168.254.16, 00:00:31 ago, via GigabitEthernet5/2

Route metric is 1954, traffic share count is 1


As soon as i make the serial link of RTR C which is connecting to RTR D , the above route to 172.29.140.25 should go off and floating static route should be prrsent in the routing table of RTR A which is not happening in this case.


What could be the problem.How to achieve redundency in this case.


Any help would be appreciated.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
smothuku Tue, 01/16/2007 - 06:51
User Badges:
  • Silver, 250 points or more

The config on RTR A is


RTRA#router eigrp 15

redistribute static

network 10.0.0.0

no auto-summary

eigrp log-neighbor-changes


and routes added on RTRA


ip route 172.29.140.0 255.255.255.128 172.16.17.121

ip route 172.29.140.0 255.255.255.128 10.30.0.126 110


Note that RTR B is running OSPF and 172.16.0.0 is allocated to OSPF network.





sundar.palaniappan Tue, 01/16/2007 - 12:46
User Badges:
  • Green, 3000 points or more

Satish,


Configure the serial link between RTR A & RTR B to run OSPF. Just configure a floating static route for this network on all the routers to point to the alternate path via RTR A-->RTR E.


This way, RTR A would learn 172.29.140.0/25 via OSPF from RTR B and when RTR A stops learning the OSPF route from RTR B the floating static route on RTR A will come into the routing table. RTR B & RTR C would act the same way as they would forward the traffic via RTR A if the route via RTR D becomes unavailable.


HTH


Sundar

smothuku Sun, 01/21/2007 - 22:40
User Badges:
  • Silver, 250 points or more


HI Sundar ,


Thanks for your reply and help.

I configured the serail link b/n RTR A and RTR b to run ospf and traffic is diveretd through RTR E as soon as I shut doen the serial link of RTR C connecting to RTR D.


If u have time then can you give some tips for preparing CCIE R & S exam.


Thanks

satish

sundar.palaniappan Mon, 01/22/2007 - 14:09
User Badges:
  • Green, 3000 points or more

Satish,


Glad to hear it helped and thanks for the rating!!


Here's a good link that provides preparation outlines and general resources for R&S Lab.


http://www.internetworkexpert.com/resources/#1


Another thing I would recommend is sign up for CCIE groupstudy (groupstudy.com) newsgroup, if you haven't already done that, and that will be of tremendous help in your preparation. Feel free to post any specific questions you may have and I shall try to respond to it promptly.


Good Luck!!


HTH


Sundar

smothuku Mon, 02/12/2007 - 02:25
User Badges:
  • Silver, 250 points or more

Hi Sundar ,


Thanks for your valuable info.


The previous problem is sorted out and I have a doght from the above setup.


RTRA(eigrp)-RTRB(a0)-RTRC(a0+a66)|-RTRD(a66)

10.0.0.0 172.16.0.0/16 |-RTDE(a66)

|-RTRF(a66)

|-RTRG(a66)


So many locations are connected to RTR C and each and every location has one ATM machine.

One tandem server is connected to RTR A and other one is connected to RTR B. RTR D to RTR G and other location ATM machines are interacting with Tandem server located at RTR B.


We are doing testing by taking RTR D ATM machine which should connect to Tandem server located at RTR A.


Tandem server ip which is connecting to RTR A is 10.17.1.3 and which is connecting to RTR B is 172.15.0.10.


If i want to connect to 10.17.1.3 from RTR D atm machine i need to do the following changes.


1. add a host route (172.15.0.10/32 )with next hop pointing to RTR A serail ip.

2.Configure a static nat on RTR A and apply it on ethernet and serial interface.


Problem is as soon as i add static route for 172.15.0.10 on RTR B all the ATM machines are communicating with RTR A tandem server.


I want RTR D ATM machine should comunicate with RTR A's tandem server and remaining locations(RTR E , RTR F and so on)should comunicate with RTR B's tandem server.


How can i accomplish this.


Many thanks in advance.


Satish


Actions

This Discussion