06-09-2010 04:59 AM - edited 03-04-2019 08:43 AM
Hi All;
Anyone can advise why can not use RIP, IS-IS and IGRP in case I was uing NBMA like FrameRelay or X.25? While I can use EIGRP and OSPF with NBMA?
Regards
Bilal
Solved! Go to Solution.
06-09-2010 05:55 AM
Hi,
ISIS worked over NBMA but only in a fully-mesh topology as it supports only pt-2-pt or broadcast network type. Please see the following link for more information:
http://www.cisco.com/en/US/partner/tech/tk365/technologies_tech_note09186a008009445a.shtml
RIP/IGRP works as well over NBMA as split-horizon is disabled by default with FR encapsulation (not for X25). If you can't send multicast update, you can switch to unicast update (neighbor + passive interface commands). Also if you have a lot of neighbor and are sending multicast updates, you may have to tune the broadcast queue.
HTH
Laurent.
06-09-2010 06:00 AM
Hello Laurent,
>> ISIS worked over NBMA but only in a fully-mesh topology
Thanks for your correction my memory betrayed me
Best Regards
Giuseppe
06-12-2010 09:28 PM
Hello Bilal,
>> From the other side, why I can not use IS-IS with NBMA if I disabled the split horizon (same as RIP)?
IS-IS is link state like OSPF there is no split horizon concept in both of them: they flood data structures (OSPF LSA for example) in all links that are in the same area.
Split horizon is a distance vector concept that says do not advertise an IP subnet out the interface it has been learned.
OSPF has many network types that allows to deal with NBMA, IS-IS has only two network types: broadcast (LAN) and point-to-point (serial) so as correctly noted by Laurent it can be used only in an NBMA with a full mesh (where each router can reach every other router without going via a third one)
You can use the neighbor statement in RIP even together with passive-interface (that will stop broadcast advertisements)
As I noted IGRP is not current anymore.
Hope to help
Giuseppe
06-13-2010 05:00 AM
Hello Bilal,
good note
>> What those other methods (other than broadcast)that can let the router knows to whom to send (specially in the beginning as the router does not know whom beside him)?
it is manually configured as for BGP
example
frame-relay multipoint interface NBMA
in ser0/0
enc frame-relay
no ip addr
no shut
int sere0/0.100 multipoint
ip address 172.16.80.1 255.255.255.240
frame-relay map ip 172.16.80.2 102 broadcast
frame-relay map ip 172.16.80.3 103 broadcast
! the broadcast keyword would allow to map RIP hellos without using the neighbor command
router rip
passive-interface ser0/0.100
neighbor 172.16.80.2
neighbor 172.16.80.3
network 172.16.0.0
version 2
see
similar setups are possible for EIGRP and OSPF (OSPF requires also configuration of appropriate network-type)
Hope to help
Giuseppe
06-09-2010 05:15 AM
Hello Bilal,
OSPF and EIGRP are recommended for NBMA but you can use for example RIP if you disable split horizon on hub router as you need to do with EIGRP.
IGRP is legacy and not supported in modern IOS images
ISIS hasn't an NBMA network mode that is present in OSPF. This makes OSPF to be preferred.
However, in ISIS is possible to configure a feature called mesh group that may be useful in dealing with NBMA
Hope to help
Giuseppe
06-09-2010 05:55 AM
Hi,
ISIS worked over NBMA but only in a fully-mesh topology as it supports only pt-2-pt or broadcast network type. Please see the following link for more information:
http://www.cisco.com/en/US/partner/tech/tk365/technologies_tech_note09186a008009445a.shtml
RIP/IGRP works as well over NBMA as split-horizon is disabled by default with FR encapsulation (not for X25). If you can't send multicast update, you can switch to unicast update (neighbor + passive interface commands). Also if you have a lot of neighbor and are sending multicast updates, you may have to tune the broadcast queue.
HTH
Laurent.
06-09-2010 06:00 AM
Hello Laurent,
>> ISIS worked over NBMA but only in a fully-mesh topology
Thanks for your correction my memory betrayed me
Best Regards
Giuseppe
06-12-2010 02:31 PM
Can I understand that OSPF and EIGRP does not use broadcast while RIP and IGRP are using broadcast? And this is the reason why NBMA is good for OSPF and EIGRP.
From the other side, why I can not use IS-IS with NBMA if I disabled the split horizon (same as RIP)?
As I understood that the problem is related to using the Broadcasting while NBMA does not allow, am correct?
Regards
Bilal
06-12-2010 09:28 PM
Hello Bilal,
>> From the other side, why I can not use IS-IS with NBMA if I disabled the split horizon (same as RIP)?
IS-IS is link state like OSPF there is no split horizon concept in both of them: they flood data structures (OSPF LSA for example) in all links that are in the same area.
Split horizon is a distance vector concept that says do not advertise an IP subnet out the interface it has been learned.
OSPF has many network types that allows to deal with NBMA, IS-IS has only two network types: broadcast (LAN) and point-to-point (serial) so as correctly noted by Laurent it can be used only in an NBMA with a full mesh (where each router can reach every other router without going via a third one)
You can use the neighbor statement in RIP even together with passive-interface (that will stop broadcast advertisements)
As I noted IGRP is not current anymore.
Hope to help
Giuseppe
06-13-2010 04:28 AM
>> You can use the neighbor statement in RIP even together with passive-interface (that will stop broadcast advertisements).
If we did this, then how the RIP will send for the routers the routing table that he has to do update? As I know that router will start send Hello for his friends to tell them what routes he has, so if we stop the broadcast, then how this will happen?
Actually the question is: those routes which does not use broadcast, or those which use point to point, how they advertise their routing table if the router does not know its neighbour and friends to send for them? What those other methods (other than broadcast)that can let the router knows to whom to send (specially in the beginning as the router does not know whom beside him)?
Your kindly help is high appreciated.
Regards
Bilal
06-13-2010 05:00 AM
Hello Bilal,
good note
>> What those other methods (other than broadcast)that can let the router knows to whom to send (specially in the beginning as the router does not know whom beside him)?
it is manually configured as for BGP
example
frame-relay multipoint interface NBMA
in ser0/0
enc frame-relay
no ip addr
no shut
int sere0/0.100 multipoint
ip address 172.16.80.1 255.255.255.240
frame-relay map ip 172.16.80.2 102 broadcast
frame-relay map ip 172.16.80.3 103 broadcast
! the broadcast keyword would allow to map RIP hellos without using the neighbor command
router rip
passive-interface ser0/0.100
neighbor 172.16.80.2
neighbor 172.16.80.3
network 172.16.0.0
version 2
see
similar setups are possible for EIGRP and OSPF (OSPF requires also configuration of appropriate network-type)
Hope to help
Giuseppe
06-14-2010 03:25 AM
Thanks for all.
1) And for IS-IS, using the broadcast keyword does not enable us to use IS-IS in NBMA?
2) Also manual configuration for IS-IS is not possible (like using passive in RIP)?
Regards
Bilal
06-14-2010 06:11 AM
Hello Bilal,
the answers is positive for 1) question , because IS-IS is not based on IP protocol but it is part of OSI stack similar to CLNS.
It is enough to look at the link provided by Laurent, but you may be not able to see it
use this public link
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009445a.shtml
frame-relay map clns 123 broadcast
this is for IS-IS hellos
clns routing
!
interface Serial1
ip address 10.10.10.1 255.255.255.0
ip router isis
encapsulation frame-relay
clns router isis
frame-relay map clns 123 broadcast
frame-relay map clns 121 broadcast
frame-relay map ip 10.10.10.3 121 broadcast
frame-relay map ip 10.10.10.4 123 broadcast
frame-relay lmi-type ansi
!
2) neighbor command is not available because it is not an IP address that identify the peer but a net + system-id that is a CLNS address
Hope to help
Giuseppe
06-23-2010 02:36 PM
Thanks for the gr8 help and kindly answers.
As there is a method to assign clns with broadcast, so why we can not use IS-IS with this broadcast configuration?
From the other side, in case of using multicast of unicast (by using the neighbour command), so why we need to use the passive command? Neighbour is not enough?
From the other side, what is the bad effect of enabling the broadcast on the Frame Relay to use it with RIP or IS-IS? What is the worst thing could happen?
Regards
Bilal
06-23-2010 02:45 PM
Hi
As there is a method to assign clns with broadcast, so why we can not use IS-IS with this broadcast configuration?
ISIS hello are send using special MAC addresses which are handled like broadcast so you don't have any choice but activating broadcast support with CLNS frame-relay mapping.
From the other side, in case of using multicast of unicast (by using the neighbour command), so why we need to use the passive command? Neighbour is not enough?
With the neighbor command only, RIP will send both the update in multicast and unicast. The passive command suppress the multicast update.
From the other side, what is the bad effect of enabling the broadcast on the Frame Relay to use it with RIP or IS-IS? What is the worst thing could happen?
If you have a lot of neighbor, you may have to tune the broadcast queue under the FR interface.
HTH
Laurent.
06-23-2010 06:15 PM
So the clns broadcast only for the IS-IS hello?
The remaining thing is why can not use the CLNS with neighbour (while it can be used with IP address)? What is the relation between net + system id and not being able to use the neighbour? Is it something related to the destination?!
In other words, why with IP address I can use the neighbour and it is not possible with CLNS?
06-24-2010 01:31 AM
Hello Bilal,
I can confirm that the neighor command is not available under router isis context.
the net is the CLNS address of the node (only one per node not one per interface)
It is a question of implementation of the protocol
in the attachment file there is a chapter that Cisco Press had given as update in 2004
Hope to help
Giuseppe
Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: