10-25-2002 08:29 AM - edited 03-02-2019 02:23 AM
Hi,
I got the following problem...
I got a Frame Relay link with a carrier from a nearby country for
terminating VoIP calls.
The configuration of my router is like the one I put below.
Current configuration:
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname myRouter
!
enable secret 5 xxx
!
!
class-map voz
match ip precedence 5
!
!
policy-map voice128
class voz
priority 128
class class-default
fair-queue
!
ip subnet-zero
!
frame-relay switching
!
interface Ethernet0
ip address 192.168.1.4 255.255.255.0
!
interface Serial0
no ip address
encapsulation frame-relay
no ip mroute-cache
frame-relay traffic-shaping
frame-relay lmi-type ansi
!
interface Serial0.2 point-to-point
ip address 10.20.1.1 255.255.255.252
no ip mroute-cache
frame-relay interface-dlci 112
class qos128
frame-relay ip rtp header-compression
!
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.1.1
ip route 172.16.0.0 255.255.0.0 10.20.1.2
no ip http server
!
!
map-class frame-relay qos128
frame-relay cir 128000
frame-relay bc 1280
frame-relay mincir 128000
no frame-relay adaptive-shaping
service-policy output voice128
frame-relay fragment 160
!
line con 0
transport input none
line vty 0 4
password xxx
login
!
end
now.. we have set up a new link with a nearby city which will not be in a
frame relay network, it's just a point to point link, between our office and
the node on the other city, which will be used for VoIP too.
At this moment the link is set up using ppp encapsulation, which is very
simple..
My boss wants to set up this link with Frame Relay using the same
configuration as above, arguing that it will improve quality, and that as
packets are encapsulated it's better,etc
So.. first of all... does it have sense to set up a frame relay for that
link, or a ppp encapsulation will be better, since the benefits of frame
relay apply only on a frame relay network and not in a simple link between 2
points??
second.. if it is better to set it up as frame relay.. then, what would be
the differences in the configuration of one router and the other.. obviously
the ip address in serial0.2 will be different for each one, both of the same
network. But what about dlci and stuff like that? Do I have to use the same
dlci on both sides?? The DTU's are dce, so the routers will have to be
dte... is this ok, or is any problem with that?
I searched for info about this at the Cisco website, but everything I found
was for frame relay networks, and couldn't find anything about setting up a
simple point to point link using frame relay..
Thanks in advance,
10-25-2002 08:36 AM
There wont be any advantage using frame-relay encap on the leased line. Still if your Boss insists, on doing it, you can do that. Frame relay back to back configuration does work. What do you need is set encapsulation to frame-relay at each end, and set the same DLCI number on each end.
frame-relay interface-dlci 100 (say) on each end. You can use any value, since its a private network.
Also you should set no keepalive on each end.
You can refer to following link.
Again there is no advantage of doing so in a P-P link. PPP would run just fine.
http://www.cisco.com/en/US/tech/tk713/tk237/technologies_configuration_example09186a0080094a3b.shtml
10-25-2002 09:03 AM
Thank you for your quick reply :)
I've just talked with the one from the other country who gave us that FR configuration, and I asked him why were we using that configuration, if it was for the priorization for VoIP packets and rtp compression..
he sayed that with ppp you can also do it, but that when he configured the link he read some docs, and it sayed that with the FR the router had less work to do, and that for some other reasons he did not remember well it was better..
yesterday I tried what you said, I put the same config on both routers, except for ip address, etc, and the same dlci..
the only difference is that I did not set the "no keepalive" and the clock, so I guess that it was because of this that it did not work, am I right?
I'll try to configure ot again..
if I have problems and can not get it to work, so I have to use ppp.. do you know of any link that shows how to do the rtp compression and VoIP packets priorizing with ppp?
thanks again
10-25-2002 09:15 AM
Here is a link to enable RTP header compression on ppp links
Here is another good link for QoS for VOIP packets on ppp leased lines.
http://www.cisco.com/en/US/tech/tk652/tk701/technologies_tech_note09186a0080094660.shtml
10-30-2002 08:59 AM
Im not sure if using frame relay will give you much improvment but using HDLC should being that it is Cisco's proprietary protocol and uses less ovehead.
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