OSPF: UNDERSTANDING PROCESS ID TOPOLOGY


PURPOSE

Configuration picked from Live Datacenter Environment, To understand How Process ID’s are configured in a Real Environment.

Take a Look at the below scenario & answer the Query given at the End


 

SCENARIO

TWO DEVICES

WAN & CORE

1. PURPOSE OF WAN DEVICE

This is the edge device, on which we have access. This device is connecting to Vendor further.

2. PURPOSE OF CORE DEVICE

This is the Core Layer device of Datacenter, connecting to WAN device further

 

LOGS

WAN#sh cdp nei

Device ID       Local Intrfce     Holdtme   Capability Platform Port ID

Fuse_core_1     Gig 2/1           155             R S I WS-C6513 Gig 13/41

PHYSICAL CONNECTION: WAN (Gig2/1) ========== CORE ( Gig 13/41)

 

WAN#sh ip ospf int g2/1 | i Process

Process ID 100, Router ID 10.146.192.252, Network Type BROADCAST, Cost: 1

 

CORE#sh ip ospf int g13/41 | i Process

Process ID 65225, Router ID 10.146.1.254, Network Type BROADCAST, Cost: 1

 

CONCLUSION

On all the interfaces of WAN device, Process ID 100 is running & On all the interfaces of CORE device, Process ID 65225 is running.

At WAN device, we have Process ID 100  & Area is 0, on interface connecting to CORE device

At Core Device, we have Process ID 65225  &  Area is 0, on interface connecting to WAN device

 

QUERY

By Default, Two process ID cannot communicate with each other, until & unless configured to exchange subnets.

How these Two routers having different process, exchanging routes with each other ?

What can be the Design Prospective in this scenario ?

 

MORE LOGS FOR REFERNCE PURPOSE 

CORE#sh ip ospf int | i Process

Process ID 65225, Router ID 10.146.1.254, Network Type POINT_TO_POINT, Cost: 1

Process ID 65225, Router ID 10.146.1.254, Network Type BROADCAST, Cost: 1

 

CORE#sh ip ospf int | i Area

Internet Address 10.146.192.161/30, Area 0

Internet Address 10.146.192.133/30, Area 0

 

WAN#sh ip ospf int | i Process

Process ID 100, Router ID 10.146.192.252, Network Type LOOPBACK, Cost: 1

Process ID 100, Router ID 10.146.192.252, Network Type BROADCAST, Cost: 1

 

WAN#sh ip ospf int | i Area

Internet Address 10.146.192.252/32, Area 0

Internet Address 10.146.203.97/28, Area 0


 

SOLUTION

Hey, Re-think about statement

” Two different process ID cannot communicate with each other “

That’s true, above statement is correct, but there is a catch in the statement. So, i am re-phrasing the statement.

” Two different Process cannot communicate with each other, if both the processes are running on same Router “

or we can say

” Process ID is locally significant  to Router “

 

Here, Two different processes are running, true, but on two different devices. So, this is a normal scenario. It will not create any problem. Routes will be exchanged between devices.

 

KEY POINT

OSPF PROCESS IS LOCALLY SIGNIFICANT TO ROUTER

 

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