cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
463
Views
0
Helpful
2
Replies

RPF check with equal IGP cost links, how is RPFcalculated?

g.pelt
Level 1
Level 1

Question is: how is rpf calculated?

Got 2 routers with 2 serials links with same bandwich

Routing is due to 2 static routers to the Loopback addresses and BGP is running between the loopback addresses.

Pim spare-mode is every ware enabled.

According to the book Developing IP Multicast Networks volume 1 page 134

The rpf should point to the highest next hop ip address.

But in real live my rpf is pointed to the lowers address, of miss I something?

Ip number 138.55.130.250 is loopback of router2

Router1>sh ip rou 138.55.130.250

Routing entry for 138.55.130.250/32

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

Routing Descriptor Blocks:

directly connected, via Serial0/1.801

Route metric is 0, traffic share count is 1

* directly connected, via Serial0/0.701

Route metric is 0, traffic share count is 1

SGSGPUE2MP999>sh ip rpf 138.55.130.250

RPF information for router2 (138.55.130.250)

RPF interface: Serial0/1.801

RPF neighbor: router2 (138.55.132.13)

RPF route/mask: 138.55.130.250/32

RPF type: unicast (static)

RPF recursion count: 0

Doing distance-preferred lookups across tables

Router1>sh ip int brief

Serial0/0.701 138.55.132.66 --> highest ip address!

Serial0/1.801 138.55.132.14

Loopback0 161.126.91.62

2 Replies 2

ssoberlik
Level 4
Level 4

The following link provides information on RPF troubleshooting

Multiple Equal Cost Paths Result in Unwanted Return Path Forwarding Behavior

http://www.cisco.com/warp/public/105/mcastguide4.html

IP Multicast Troubleshooting Guide

http://www.cisco.com/en/US/tech/tk648/tk363/technologies_tech_note09186a0080094b55.shtml

Both links explain that the RPF pointed to the highest next hop ip address.

in my example it's the Lowers IP address....

Review Cisco Networking for a $25 gift card