Re: Classical IP and SVC's

From: gladston@br.ibm.com
Date: Wed Jun 29 2005 - 19:08:53 GMT-3


Hi Lee,

==============
quoted
I believe one of the requirements is PVC 0/5 for
qssal so that your router may talk with the ATM switch
so that it can receive the NSAP addresses.
===============

PVC0/5, qssal, "make the path" (SVC) between the routers.
PVC0/16, ilmi, will send the NSAP address to the router (the prefix, from the atm switch).

You can check it using show atm ilmi-status.

====================
quoted
What I don't get is that if you wanted to disable
classical IP... would you have to statically configure
your SVC devices? This I would assume you knew what
they were?

I am thinking it is much like iverse-arp on
frame-relay in that if you disable it you must create
a mapping from the protocol to the DLCI (or protocol
to ESI on ATM) in order for things to continue to
work. Also, that inverse-arp or classical ip are
disabled on point-to-point interfaces.
====================

When using Classical IP your routers connects to the ARP server and inform its atm address/IP. So other routers can discover the atm address requesting this information to the ARP Server. Can you see it? Router A wants to send packets to x.x.x.x. Router A asks the ARP Server: -which atm address does router with x.x.x.x use?

=====================
quoted
Does anyone have a good configuration example of an
SVC with classical IP disabled? Or maybe be able to
explain it better. Also, I remember a command you can
enter to get the ATMs address if not given, once
qssal is enabled. Anyone have that handy?
====================

There is no need to disabe classical IP. It is there only if you configure it (atm arp-server...)

Example of classical IP:

interface ATM1/0
 pvc 0/5 qsaal
 !
 pvc 0/16 ilmi
 !
interface ATM1/0.269 multipoint
 description Classical-IP
 ip address 172.16.99.6 255.255.255.0
 atm esi-address 266666666666.00
 atm arp-server nsap 47.00000000000000000000000A.299999999999.00

Example of SVC with mapping configured manually:

interface ATM1/0
 pvc 0/5 qsaal
 pvc 0/16 ilmi
 !
!
interface ATM1/0.69 multipoint
 description PVC
 ip address 150.100.3.6 255.255.255.0
 ip verify unicast reverse-path
 pvc 1/100
  protocol ipv6 FE80::203:6BFF:FE37:C2A1 broadcast
  protocol ipv6 2001:AAAA:BBBB:69::9 broadcast
  protocol ip 150.100.3.254 broadcast
  vbr-nrt 2000 1000
 !
 ipv6 address 2001:AAAA:BBBB:69::6/64
 ipv6 rip RIP enable
 ipv6 rip RIP summary-address 2001::/16
!
interface ATM1/0.169 multipoint
 description SVC with manual mapping
 ip address 172.16.169.6 255.255.255.0
 atm esi-address 666666666666.00
 !
 svc nsap 47.00000000000000000000000A.999999999999.00
  protocol ip 172.16.169.9 broadcast
  ubr 1000

You may ask: How do you get the nsap address on the second example?
The answer is: I configure ilmi on the remote router, typed 'show atm ilmi-status' and get it.



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