Today I looked at the different frame relay configuration. I just done this in a lab
with 3 of the router r1,r4 and r5
My findings below
Main Interface-Main Interface full mesh connectivity
So first lab was main interfaces on all configured and inverse arp is on + topology is
in a full mesh
so
r1 local dlci 105 - r5 local dlci 501
r1 local dlci 104 - r4 local dlci 401
r4 local dlci 405 - r5 local dlci 504
The first thing i noticed when you enable encap frame relay on the router interfaces
+ give it an ip. Inverse arp is going kick in and it will send out inverse arp reques
on all the dlci lmi has picked up. As the lab is in full mesh you may start recieving
replies from other routers you do not want in the scope. So i had r3 configured from
last night and it picked up that and created a map entry for it.
so on r1 i have configured the following
interface Serial0/0
ip address 10.229.254.1 255.255.255.0
encapsulation frame-relay
frame-relay lmi-type cisco
This config will be the same on each of the routers apart from ip address so r1
10.229.254.1 r2 10.229.254.1 r5 10.229.254.3
r1#sh frame-relay map
Serial0/0 (up): ip 12.12.12.12 dlci 103(0x67,0x1870), dynamic,
broadcast,, status defined, active
Serial0/0 (up): ip 10.229.254.2 dlci 104(0x68,0x1880), dynamic,
broadcast,, status defined, active
Serial0/0 (up): ip 10.229.254.3 dlci 105(0x69,0x1890), dynamic,
broadcast,
CISCO, status defined, active
Notice it has pick up 12.12.12.12 ?? this was configured on r3 which i do not want in
the topology.
As this is potential issue in the ccie lab which is full meshed. To resolve this we
can do the following.
You can manually assign the rogue dlci to a sub interface
r1#sh run int s0/0.1
!interface Serial0/0.1 multipoint
frame-relay interface-dlci 103
end
this will run iverse arp as there has been no ip address assigned
r1#sh frame-relay map
Serial0/0 (up): ip 10.229.254.2 dlci 104(0x68,0x1880), dynamic,
broadcast,, status defined, active
Serial0/0 (up): ip 10.229.254.3 dlci 105(0x69,0x1890), dynamic,
broadcast,
CISCO, status defined, active
I only see the 2 required subnets that i want
I have full connectivity
r1#ping 10.229.254.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.229.254.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/65/68 ms
r1#ping 10.229.254.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.229.254.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/65/68 ms
r1#
Main-interface to main-interface partial mesh
so in this i will do it as if r1 is the hub and r4 + 5 are spokes. R4 + R5 do not have
connectivity to each other
r1 local dlci 105 - r5 local dlci 501
r1 local dlci 104 - r4 local dlci 401
At the moment it is still in full connectivity
r5(config-subif)#do sh frame-relay map
Serial0/0/0 (up): ip 10.229.254.1 dlci 501(0x1F5,0x7C50), dynamic,
broadcast,
CISCO, status defined, active
Serial0/0/0 (up): ip 12.12.12.12 dlci 503(0x1F7,0x7C70), dynamic,
broadcast,, status defined, active
Serial0/0/0 (up): ip 10.229.254.2 dlci 504(0x1F8,0x7C80), dynamic,
broadcast,,
In order to get rid of the dlci between r5 - r4
nterface Serial0/0/0.1 multipoint
frame-relay interface-dlci 503
frame-relay interface-dlci 504
end
i have assigned the dlci 503 to the subinterface multipoint turning of inverse arp on
that sub interface i also done 504 to get rid of the 12.12.12.12 network
r5#sh frame-relay map
Serial0/0/0 (up): ip 10.229.254.1 dlci 501(0x1F5,0x7C50), dynamic,
broadcast,
CISCO, status defined, active
so i only have one frame-relay map learnt via inverse arp to r1
I need to repeat the above on r4
Ok so from r4 i can ping 10.229.254.1 r1 but not 10.229.254.3 r5
r4#ping 10.229.254.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.229.254.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/65/68 ms
r4#ping 10.229.254.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.229.254.3, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
r4#
This is down to not have a frame-relay map statement for it
ok i have added a frame-relay map statement on r4. One thing to note when you add a
frame-relay map it will turn off inverse arp. So you will need to manually add one for
r1 also
r1 can ping but r5 is still not responding i need to add frame-relay map on r5 also
so success both ways after manually mapping
Sending 5, 100-byte ICMP Echos to 10.229.254.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/65/68 ms
r5#ping 10.229.254.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.229.254.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 128/131/140 ms
r5#
OK i will go onto the next one a quick way to reset your config on each interface on
r1 r3 r5 do an encap ppp and then back to encap frame-relay reset the interface to
base config with ip set. I am going turn off r3 to stop recieving the 12.12.12.12
network
Multipoint sub interface on r1, p2p sub int on r4 and main interface on r5 in partial
mesh
r1 local dlci 105 - r5 local dlci 501
r1 local dlci 104 - r4 local dlci 401
so i will start r1 everything is in it main interface config
r1
-----
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 multipoint
ip address 10.229.254.1 255.255.255.0
r1#sh frame-relay map
r1#
so after enabling multipoint i have lost all frame-relay mappings
i need to specify what dlci are on the interface to be used
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 multipoint
ip address 10.229.254.1 255.255.255.0
frame-relay interface-dlci 104
frame-relay interface-dlci 105
it now has both map entries learnt through inverse arp
r1#sh frame-relay map
Serial0/0.1 (up): ip 10.229.254.2 dlci 104(0x68,0x1880), dynamic,
broadcast,, status defined, active
Serial0/0.1 (up): ip 10.229.254.3 dlci 105(0x69,0x1890), dynamic,
broadcast,, status defined, active
and both are pinging
r5
-----
interface Serial0/0/0
no ip address
encapsulation frame-relay
no fair-queue
!
interface Serial0/0/0.1 point-to-point
ip address 10.229.254.3 255.255.255.0
r5#sh frame-relay map
r5#
no frame-relay map i will specify the dlci it is to use
interface Serial0/0/0.1 point-to-point
ip address 10.229.254.3 255.255.255.0
frame-relay interface-dlci 501
!
r5#sh frame-relay map
Serial0/0/0.1 (up): point-to-point dlci, dlci 501(0x1F5,0x7C50), broadcast
status defined, active
r5#
notice it has no ip address mapped it just says point to point dlci 501. This basically because it is point to point it knows it only has one dlci so the way the router looks at it is that all traffic should forward out there
r5#ping 10.229.254.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.229.254.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/65/68 ms
r5#
I can ping r1 but not r4 .
r4
---
On r4 i put
debug ip packet
the output as follows when i try ping from r5. R5 is reaching it but it is unable to reply
*Dec 5 21:27:44.531: IP: tableid=0, s=10.229.254.3 (Serial0/0/0), d=10.229.254.2 (Serial0/0/0), routed via RIB
*Dec 5 21:27:44.531: IP: s=10.229.254.3 (Serial0/0/0), d=10.229.254.2 (Serial0/0/0), len 100, rcvd 3
*Dec 5 21:27:44.531: IP: tableid=0, s=10.229.254.2 (local), d=10.229.254.3 (Serial0/0/0), routed via RIB
*Dec 5 21:27:44.531: IP: s=10.229.254.2 (local), d=10.229.254.3 (Serial0/0/0), len 100, sending
*Dec 5 21:27:44.531: IP: s=10.229.254.2 (local), d=10.229.254.3 (Serial0/0/0), len 100, encapsulation failed
Encapsulation failed
it has no defined map for 10.229.254.3
r4#sh frame-relay map
Serial0/0/0 (up): ip 10.229.254.1 dlci 401(0x191,0x6410), dynamic,
broadcast,, status defined, active
By adding a map statement for both .3 and .1 the topology is complete i can ping from everywhere
interface Serial0/0/0
ip address 10.229.254.2 255.255.255.0
encapsulation frame-relay
no fair-queue
frame-relay map ip 10.229.254.3 401
frame-relay map ip 10.229.254.1 401
One of the things to watch for
frame-relay map ip when you are using the same dlci for multiple destinations like in the above 401
if you require support for broadcast or multicast you need to specify the broacast keyword after the map statement. This only has to specfied once for protocol + dlci
so for example in the above
frame-relay map ip 10.229.254.3 401 broadcast
frame-relay map ip 10.229.254.1 401
you would only specify it once as if you specify it again it treats it as another broadcast so pseudo broadcast for every dlci with the broacast even if they are the same so you are generating aload of traffic for no reason on the dlci.
Note if you were using ipv6 with the same dlci as it is a different protocol you need to specify it once for that also
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