Illegal HDLC error

[alister9000]

hi everyone,

so i just got a t1 line and when i configure the IP address i get this error message

Illegal HDLC serial type code 972, PC=0x213FEF40

before this error comes, i am able to ping for about 5 seconds, after the error the port shuts down.

now, i found out that this is because the router received a piece of information and it doesnt know what to do with it, and it has to do with encapsulation.

im a little green about cisco routers, so i was wondering if someone can help me figure out how to fix this. I talk with the isp and they told me that there's nothing they can do to help. they provided me with an adtran t1 device so i can connect it to the ethernet port but i dont have any ethernet port left on the router so i need to use the t1 port.

is there anyway i can configure the router to ignore that error? because im assuming that if im beeing able to ping for a couple seconds until that error it means that outside that error everything is fine.

i dont know if it matters but i have a cisco 1921 router..

thanks,

[alister9000]

j.blakley wrote:
If it works while connected to the ethernet port, the circuit is configured for FR. It's best that you contact them for the settings that you need. If you have the interface up while configured for FR (as you are now), does the interface go up/up?

yes its serial0/0/0 is up, line protocol is up

[John Blakley]

Ok...how are you testing? From the router, you should be able to ping your provider. I'm assuming they're at 1.1.1.2 since you're using .1 on a /30. You can try to ping them from the router. If that's successful, your circuit is up but you'll need to configure your router for natting.

HTH,

John

Please rate all useful posts..

[alister9000]

j.blakley wrote:
Ok...how are you testing? From the router, you should be able to ping your provider. I'm assuming they're at 1.1.1.2 since you're using .1 on a /30. You can try to ping them from the router. If that's successful, your circuit is up but you'll need to configure your router for natting.
HTH,
John
Please rate all useful posts..

without the frame-relay i would configure the ip address and i would be able to ping the ISP for a couple of seconds until the HDLC error comes up after that it goes down and i cant bring it up again for a while.

with the frame-relay command i cant ping at all.

[John Blakley · Accepted solution]

You'll need to contact the ISP to get the appropriate settings. They have FR configured on their router and that should translate to the Cisco with no issues. The fact that the interface comes up and stays up is proof enough that FR encapsulation is used. The only thing you haven't done is change the encapsulation type:

int s0/0/0.500

encapsulat frame-relay ietf

[alister9000]

j.blakley wrote:
You'll need to contact the ISP to get the appropriate settings. They have FR configured on their router and that should translate to the Cisco with no issues. The fact that the interface comes up and stays up is proof enough that FR encapsulation is used. The only thing you haven't done is change the encapsulation type:
int s0/0/0.500
encapsulat frame-relay ietf

success!!

that did the trick, thank you so much for you help.

i am able to ping now,altough the interface s0/0/0.500 disappeared for some reason.this is my sh run output

!

no aaa new-model

!

!

no ipv6 cef

ip source-route

ip cef

!

!

!

ip dhcp excluded-address 192.168.1.2 192.168.1.50

!

ip dhcp pool bartz

network 192.168.1.0 255.255.255.0

default-router 192.168.1.1

dns-server

!

!

!

!

!

!

!

!

!

interface Embedded-Service-Engine0/0

no ip address

shutdown

!

interface GigabitEthernet0/0

description inside

ip address 192.168.1.1 255.255.255.0

ip nat inside

ip virtual-reassembly in

duplex auto

speed auto

no mop enabled

!

interface GigabitEthernet0/1

description  Outside

ip address 2.2.2.2 255.255.255.0

ip nat outside

ip virtual-reassembly in

duplex auto

speed auto

!

interface Serial0/0/0

description T1

no ip address

encapsulation frame-relay IETF

!

ip default-gateway 2.2.2.2

ip forward-protocol nd

!

ip http server

ip http access-class 23

ip http authentication local

ip http secure-server

ip http timeout-policy idle 60 life 86400 requests 10000

!

ip nat inside source list 101 interface GigabitEthernet0/1 overload

ip nat inside source static tcp 192.168.1.20 80 interface GigabitEthernet0/1 80

ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/1

ip route 192.168.2.0 255.255.255.0 192.168.1.2

!

access-list 101 permit ip 192.168.1.0 0.0.0.255 any

access-list 101 permit ip 192.168.2.0 0.0.0.255 any

!

!

!

!

!

!

[John Blakley]

David,

Glad to hear, although I'm a bit confused How are you able to get a response with no address on the interface? Try this since changing the encapsulation type worked:

interface Serial0/0/0.500 point-to-point

ip address 1.1.1.1 255.255.255.252

frame-relay interface-dlci 500

The next thing will be to get your natting set up after you get the pings working across the link. When you get this set up, post:

"sh frame-relay map"

HTH,

John

[alister9000]

j.blakley wrote:
David,
Glad to hear, although I'm a bit confused  How are you able to get a response with no address on the interface? Try this since changing the encapsulation type worked:
interface Serial0/0/0.500 point-to-point
ip address 1.1.1.1 255.255.255.252
frame-relay interface-dlci 500
The next thing will be to get your natting set up after you get the pings working across the link. When you get this set up, post:
"sh frame-relay map"
HTH,
John

i did the s0/0/0.500 and this is the output for the sh frame-relay map

Router#sh frame-relay map

Serial0/0/0.500 (up): point-to-point dlci, dlci 500(0x1F4,0x7C40), broadcast, BW = 1536000

          status defined, active

[John Blakley]

Ok. It looks like everything is running now. You can look at your running config and should be able to see the address on the subinterface now. Hopefully

Sent from Cisco Technical Support iPhone App

[alister9000]

j.blakley wrote:
Ok. It looks like everything is running now. You can look at your running config and should be able to see the address on the subinterface now. Hopefully 
Sent from Cisco Technical Support iPhone App

yes and i used the extended ping to make sure i am using that interface and ip address and it worked, so now i have to work on the routing, thanks for all the help