Posted by: Richard @ | January 22, 2008

Day 2 of Week 3

Another evening’s work almost complete and I’m feeling much better about things now.  Thank goodness I’m working with someone who actually knows what he is doing!  As mentioned as a task in my last post I have now read through a couple of web pages covering frame-relay and although I took a lot of it in it was my colleague who really simplified things for m; I felt simple by the end of it 😦

Some key points I have picked up about Frame-relay:

Frame-relay = NBMA

LMI messages are between local router and local FR switch
LMI type default = autosense
Manual configuration = frame-relay lmi-type ‘type’

InARP is between local router and remote router (forwarded by FR switch)
Replies can’t be stopped but interface can be set to stop sending InARP
Remember ‘broadcast’ keyword for manual mapping – InARP usually deals with this
OSPF is non-broadcast by default on physical serial interfaces so network type always has to be changed for FR

If subinterfaces are used you need to configure the interface DLCI
frame-relay interface-dlci ‘no.’

States (show frame-relay pvc):
Active – All OK
Inactive – Remote side is down
Deleted – Local side is down

Advised before any change:
interface shut
clear frame-relay inarp
‘make change’
interface no shut

Much of this is probably pretty basic stuff for most people on the CCIE learning track
but because of limited exposure to frame-relay in the past I have never really ‘got it’ – hopefully I’ve got the understanding I need to move on now.

Quick mention: I have now unsubscribed myself from the Cisco NetPro RSS feed – the success rate of finding useful information is too low to warrant checking the posts anymore.

I scored 9/10 on the ‘IP Forwarding’ test so hopefully when I buy a test database this small chapter won’t be one of my weaknesses.

Here is another useful link to a short page covering some useful CEF commands:

How to Verify Cisco Express Forwarding Switching

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