Re: Frame-Relay Encapsulation Failed -- Driving me mad

From: joe_astorino@comcast.net
Date: Sat Jan 24 2009 - 04:35:32 ARST

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OK having thought about this more, I THINK what you are saying is that basically by the time it looked up 4.4.4.4 in the routing table, saw that the next hop was to 141.41.26.5, then looked THAT up for the L2 mapping to DLCI 602 that the packet had essentially "timed out" ..... because it took too long. Is that about accurate?

I don't know...I mean CEF and caching is good stuff, but should we really have to absolutely rely on it for basic forwarding? I like the way you are thinking though!

- Joe

----- Original Message -----
From: "Pavel Bykov" <slidersv@gmail.com>
To: "Joe Astorino" <joe_astorino@comcast.net>
Cc: smorris@internetworkexpert.com, ccielab@groupstudy.com
Sent: Saturday, January 24, 2009 12:09:24 AM GMT -05:00 US/Canada Eastern
Subject: Re: Frame-Relay Encapsulation Failed -- Driving me mad

This came to me in a dream from which I just woke up, so take with salt:
Basically it was a recursivity problem. A packet came in, it had to be processed by getting translated from broadcast to unicast, then the packet had to be forwarded, but the next hop had to be resolved, because there was no cache-entry, so after resolving the next hop the packet was almost forwarded, but it was processed too many times to finish processing correctly.

Adding map to 4.4.4.4 solved the problem because you didn't need to resolve next hop.
The sure way to test if the problem is this dream thing, is to overcome that last recursive lookup somehow. Basically setting IP of helper to the address that is already resolved. Like static route that points out of the interface only (no next hop), but the interface would have to be point to point for that to work correctly.

Again, that was the dream, so... yeah..

On Sat, Jan 24, 2009 at 2:23 AM, Joe Astorino < joe_astorino@comcast.net > wrote:

Hey Scott,

Still no dice. I removed the 3 dhcp relay commands as requested. On a side
note, if I create an ethernet subinterface on R6, e0/0.200 , give it an ip
address in VLAN 200 (R4s ethernet), and trunk it down to the switch (so R6
and R4 have ethernet interfaces in the same vlan) and make the
helper-address R4s ethernet address it works fine. It just seems to be an
issue with the serial interface for some reason.

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-----Original Message-----
From: Scott Morris [mailto: smorris@internetworkexpert.com ]

Sent: Friday, January 23, 2009 7:35 PM

To: 'Joe Astorino'; 'Pavel Bykov'
Cc: ccielab@groupstudy.com
Subject: RE: Frame-Relay Encapsulation Failed -- Driving me mad

Nothing's leaping out at me there... but what if you remove all your dhcp
relay commands (two global and one interface). Let's rule that out of the
equation as see if the "raw" method of forwarding works there.

Scott

-----Original Message-----
From: Joe Astorino [mailto: joe_astorino@comcast.net ]
Sent: Friday, January 23, 2009 7:31 PM
To: smorris@internetworkexpert.com ; 'Pavel Bykov'
Cc: ccielab@groupstudy.com
Subject: RE: Frame-Relay Encapsulation Failed -- Driving me mad

Hey Scott, I'd be very happy to post that information. Here you go! Thanks
for the time. If you'd like to get your hands dirty I will glady provide
you with a login to my rack.

=~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2009.01.23 19:26:05
=~=~=~=~=~=~=~=~=~=~=~= term len 0 R6#show ver Cisco IOS Software, 3600
Software (C3640-IK9O3S-M), Version 12.4(19), RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2008
by Cisco Systems, Inc.
Compiled Fri 29-Feb-08 22:36 by prod_rel_team

ROM: System Bootstrap, Version 11.1(20)AA2, EARLY DEPLOYMENT RELEASE
SOFTWARE (fc1)

R6 uptime is 5 hours, 31 minutes
System returned to ROM by reload at 13:43:19 EST Fri Jan 23 2009 System
image file is "flash:c3640-ik9o3s-mz.124-19.bin"

This product contains cryptographic features and is subject to United States
and local country laws governing import, export, transfer and use. Delivery
of Cisco cryptographic products does not imply third-party authority to
import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for compliance
with U.S. and local country laws. By using this product you agree to comply
with applicable laws and regulations. If you are unable to comply with U.S.
and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found
at:
http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to
export@cisco.com .

Cisco 3640 (R4700) processor (revision 0x00) with 98304K/32768K bytes of
memory.
Processor board ID 26454825
R4700 CPU at 100MHz, Implementation 33, Rev 1.0
2 Ethernet interfaces
4 Serial interfaces
DRAM configuration is 64 bits wide with parity disabled.
125K bytes of NVRAM.
32768K bytes of processor board System flash (Read/Write)

Configuration register is 0x2102

R6#sh running-config
Building configuration...

Current configuration : 3073 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R6
!
boot-start-marker
boot-end-marker
!
logging buffered 4096 debugging
!
no aaa new-model
memory-size iomem 25
clock timezone EST -5
clock summer-time EDT recurring
!
!
ip cef
no ip domain lookup
ip dhcp relay information option
ip dhcp relay information trust-all
!
!
ip multicast-routing
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
key chain EIGRP
key 1
key-string cisco
accept-lifetime 00:00:00 Jan 1 1993 infinite
send-lifetime 00:00:00 Jan 1 1993 infinite !
interface Loopback1
ip address 6.6.6.6 255.255.255.255
ip pim sparse-mode
ip igmp join-group 225.0.0.6
!
interface Ethernet0/0
ip dhcp relay information trusted
ip address 141.41.67.6 255.255.255.0
ip helper-address 4.4.4.4
ip authentication mode eigrp 679 md5
ip authentication key-chain eigrp 679 EIGRP half-duplex !
interface Ethernet0/1
no ip address
shutdown
half-duplex
!
interface Serial2/0
ip address 141.41.26.6 255.255.255.0
ip pim sparse-mode
encapsulation frame-relay
no ip route-cache cef
no ip route-cache
ip ospf authentication message-digest
ip ospf message-digest-key 1 md5 cisco
ip ospf network broadcast
ip ospf priority 0
serial restart-delay 0
frame-relay map ip 141.41.26.2 602 broadcast frame-relay map ip
141.41.26.5 602 broadcast frame-relay map ip 141.41.26.6 602 broadcast no
frame-relay inverse-arp frame-relay lmi-type cisco !
interface Serial2/1
ip address 141.41.69.6 255.255.255.0
serial restart-delay 0
!
interface Serial2/2
ip address 141.41.70.6 255.255.255.0
serial restart-delay 0
!
interface Serial2/3
no ip address
shutdown
serial restart-delay 0
!
router eigrp 679
redistribute ospf 1 metric 1 1 1 1 1
network 6.6.6.6 0.0.0.0
network 141.41.67.0 0.0.0.255
network 141.41.69.0 0.0.0.255
network 141.41.70.0 0.0.0.255
no auto-summary
!
router ospf 1
router-id 6.6.6.6
log-adjacency-changes
area 256 virtual-link 2.2.2.2
redistribute eigrp 679 subnets
network 6.6.6.6 0.0.0.0 area 0
network 141.41.26.0 0.0.0.255 area 256
!
router bgp 256
no synchronization
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 256
neighbor 2.2.2.2 update-source Loopback1 neighbor 9.9.9.9 remote-as 66
neighbor 9.9.9.9 local-as 99 neighbor 9.9.9.9 ebgp-multihop 255 neighbor
9.9.9.9 update-source Loopback1 no auto-summary !
ip http server
no ip http secure-server
!
ip forward-protocol nd
!
access-list 101 permit udp any any eq bootpc access-list 101 permit udp any
any eq bootps access-list 101 permit udp any any access-list 102 permit icmp
any any !
!
!
control-plane
!
line con 0
exec-timeout 0 0
logging synchronous
line aux 0
line vty 0 4
login
!
ntp clock-period 17179878
ntp server 5.5.5.5
!
end

R6#exit

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-----Original Message-----
From: Scott Morris [mailto: smorris@internetworkexpert.com ]
Sent: Friday, January 23, 2009 7:13 PM
To: joe_astorino@comcast.net ; 'Pavel Bykov'
Cc: ccielab@groupstudy.com
Subject: RE: Frame-Relay Encapsulation Failed -- Driving me mad

Could you post the entire "show run" output and software version you have?
That may be simpler.

helper addresses aren't exactly a bleeding edge feature. :)

Scott

-----Original Message-----
From: nobody@groupstudy.com [mailto: nobody@groupstudy.com ] On Behalf Of
joe_astorino@comcast.net
Sent: Friday, January 23, 2009 4:55 PM
To: Pavel Bykov
Cc: ccielab@groupstudy.com
Subject: Re: Frame-Relay Encapsulation Failed -- Driving me mad

Hey guys,

The general idea from several experts thusfar is that this has to be a
"feature" and to try different code. It seems to ONLY effect dhcp traffic
going out the serial frame interface. I will try the T train code
recommended earlier in this thread tonight and try to keep you all posted.

Thanks for the support

- Joe

----- Original Message -----
From: "Pavel Bykov" < slidersv@gmail.com >
To: "joe astorino" < joe_astorino@comcast.net >
Cc: ccielab@groupstudy.com
Sent: Friday, January 23, 2009 1:38:42 PM GMT -05:00 US/Canada Eastern
Subject: Re: Frame-Relay Encapsulation Failed -- Driving me mad

no FIB because R6 is using control plane for translation.

On Fri, Jan 23, 2009 at 7:21 PM, < joe_astorino@comcast.net > wrote:

Interesting .... if I look at the debug of the successful ping to 4.4.4.4
from R6's ethernet address I see something I do NOT see when it fails encap.

R6(config-if)#do ping 4.4.4.4 so e0/0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
Packet sent with a source address of 141.41.67.6 !
*Jan 23 18:13:03.869: IP: tableid=0, s=141.41.67.6 (local), d=4.4.4.4
(Serial2/0), routed via FIB *Jan 23 18:13:03.873: IP: s=141.41.67.6 (local),
d=4.4.4.4 (Serial2/0), len 100, sending *Jan 23 18:13:03.873: ICMP type=8,
code=0

Notice that on the first line it says "routed via FIB". When it fails I do
not see that. hmmmmmmm.............

----- Original Message -----
From: "joe astorino" < joe_astorino@comcast.net >
To: "Pavel Bykov" < slidersv@gmail.com >
Cc: ccielab@groupstudy.com

Sent: Friday, January 23, 2009 12:35:38 PM GMT -05:00 US/Canada Eastern
Subject: Re: Frame-Relay Encapsulation Failed -- Driving me mad

Hi guys,

Thanks to everybody that is chipping in on this one. It sure is a
frustrating issue! Yes, I have tried pinging 4.4.4.4 sourced from R6's
ethernet (141.41.67.6) and it works just fine. That was actually one of the
first things I tried. Scott, no I have not turned off any services or done
anything "strange." The startup configurations are pretty straight forward,
just interfaces and IP addresses, and I have carefully looked them over
again just to be sure.

Pavel -- I also thought of it possibly being related to CEF so I did try
making sure ip cef was on and also ip route-cache cef on all interfaces. I
can even see the 4.4.4.4 entry in the cef table pointing to the correct next
hop....and like I said I can ping it fine even sourced from R6's ethernet.

Just for fun, here are my frame configurations from R6, and some logs. maybe
you guys see something I don't!

interface Serial2/0
ip address 141.41.26.6 255.255.255.0
ip pim sparse-mode
encapsulation frame-relay
ip ospf authentication message-digest
ip ospf message-digest-key 1 md5 cisco
ip ospf priority 0
serial restart-delay 0
frame-relay map ip 141.41.26.2 602 broadcast frame-relay map ip 141.41.26.5
602 broadcast frame-relay map ip 141.41.26.6 602 broadcast no frame-relay
inverse-arp frame-relay lmi-type cisco

R6#sh frame map
Serial2/0 (up): ip 141.41.26.2 dlci 602(0x25A,0x94A0), static, broadcast,
CISCO, status defined, active Serial2/0 (up): ip 141.41.26.5 dlci
602(0x25A,0x94A0), static, broadcast, CISCO, status defined, active
Serial2/0 (up): ip 141.41.26.6 dlci 602(0x25A,0x94A0), static, broadcast,
CISCO, status defined, active

Ok looks good.....lets ping 4.4.4.4 sourced from our loopback and e0/0

R6#ping 4.4.4.4 so lo1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
Packet sent with a source address of 6.6.6.6 !!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 196/205/236 ms
R6#ping 4.4.4.4 so e0/0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
Packet sent with a source address of 141.41.67.6 !!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 196/197/200 ms

OK how about a traceroute for good measure???

R6#trace 4.4.4.4

Type escape sequence to abort.
Tracing the route to 4.4.4.4

1 141.41.26.2 36 msec 32 msec 36 msec
2 141.41.26.5 76 msec 64 msec 68 msec
3 141.141.45.4 96 msec * 96 msec

exactly as expected....it goes up to the frame hub, down to R5, then over to
R4 through the PPPoFR virtual-template.

Now, at this point R8 has an interface set for "ip dhcp" on the
141.41.67.0/24 subnet. Here is a debug ip packet of what is going on.

R6#sh access-list 101
Extended IP access list 101
10 permit udp any any eq bootpc
20 permit udp any any eq bootps
30 permit udp any any
R6#debug ip packet 101 det
IP packet debugging is on (detailed) for access list 101

*Jan 23 17:22:51.464: IP: s=0.0.0.0 (Ethernet0/0), d=255.255.255.255, len
604, rcvd 2 *Jan 23 17:22:51.464: UDP src=68, dst=67 *Jan 23 17:22:51.468:
IP: s=141.41.67.6 (local), d=4.4.4.4 (Serial2/0), len 604, sending *Jan 23
17:22:51.468: UDP src=67, dst=67 *Jan 23 17:22:51.468: IP: s=141.41.67.6
(local), d=4.4.4.4 (Serial2/0), len 604, encapsulation failed *Jan 23
17:22:51.468: UDP src=67, dst=67

Again, we see the DHCP broadcast come in from R8. We attempt to unicast a
DHCP request packet to 4.4.4.4 and it poops.

Now, we add a frame-map to 4.4.4.4 which DOESN'T MAKE ANY SENSE and it
works!

R6(config)#int s2/0
R6(config-if)#frame map ip 4.4.4.4 602

R6(config-if)#do sh frame map
Serial2/0 (up): ip 4.4.4.4 dlci 602(0x25A,0x94A0), static, CISCO, status
defined, active Serial2/0 (up): ip 141.41.26.2 dlci 602(0x25A,0x94A0),
static, broadcast, CISCO, status defined, active Serial2/0 (up): ip
141.41.26.5 dlci 602(0x25A,0x94A0), static, broadcast, CISCO, status
defined, active Serial2/0 (up): ip 141.41.26.6 dlci 602(0x25A,0x94A0),
static, broadcast, CISCO, status defined, active

*Jan 23 17:27:53.324: IP: s=0.0.0.0 (Ethernet0/0), d=255.255.255.255, len
604, rcvd 2 *Jan 23 17:27:53.324: UDP src=68, dst=67 *Jan 23 17:27:53.328:
IP: s=141.41.67.6 (local), d=4.4.4.4 (Serial2/0), len 604, sending *Jan 23
17:27:53.328: UDP src=67, dst=67 R6(config-if)# *Jan 23 17:27:56.152: IP:
tableid=0, s=141.141.45.4 (Serial2/0),
d=141.41.67.6 (Ethernet0/0), routed via RIB *Jan 23 17:27:56.152: IP:
s=141.141.45.4 (Serial2/0), d=141.41.67.6, len 328, rcvd 4 *Jan 23
17:27:56.152: UDP src=67, dst=67 *Jan 23 17:27:56.156: IP: s=141.41.67.6
(local), d=255.255.255.255 (Ethernet0/0), len 328, sending broad/multicast
*Jan 23 17:27:56.156: UDP src=67, dst=68 *Jan 23 17:27:56.160: IP: s=0.0.0.0
(Ethernet0/0), d=255.255.255.255, len 604, rcvd 2 *Jan 23 17:27:56.160: UDP
src=68, dst=67 *Jan 23 17:27:56.164: IP: s=141.41.67.6 (local), d=4.4.4.4
(Serial2/0), len 604, sending *Jan 23 17:27:56.164: UDP src=67, dst=67
R6(config-if)# *Jan 23 17:27:56.992: IP: tableid=0, s=141.141.45.4
(Serial2/0),
d=141.41.67.6 (Ethernet0/0), routed via RIB *Jan 23 17:27:56.992: IP:
s=141.141.45.4 (Serial2/0), d=141.41.67.6, len 328, rcvd 4 *Jan 23
17:27:56.992: UDP src=67, dst=67 *Jan 23 17:27:56.992: IP: s=141.41.67.6
(local), d=255.255.255.255 (Ethernet0/0), len 328, sending broad/multicast
*Jan 23 17:27:56.996: UDP src=67, dst=68

R8(config-if)#do sh ip int brie
Interface IP-Address OK? Method Status Protocol FastEthernet0/0 141.41.67.27
YES DHCP up up

Am I going insane or what?!

- Joe

----- Original Message -----
From: "Pavel Bykov" < slidersv@gmail.com >
To: "joe astorino" < joe_astorino@comcast.net >
Cc: ccielab@groupstudy.com
Sent: Friday, January 23, 2009 11:44:41 AM GMT -05:00 US/Canada Eastern
Subject: Re: Frame-Relay Encapsulation Failed -- Driving me mad

Looks like control plane / data plane issue to me

Try "ip cef" on all routers and "ip route-cache cef" on all interfaces.

On Fri, Jan 23, 2009 at 9:01 AM, < joe_astorino@comcast.net > wrote:

Hello everybody. I am hoping somebody might be able to explain to me an
issue I am having regarding frame-relay that is driving me mad in the
practice lab. Here is the scenario:

R2, R5, R6 are in a frame-relay hub/spoke topology whereby R2 is the hub.
DLCIs are X0Y where X is the source router number and Y is the destination
router number. Additionally, R5 has a PPPoFR link to R4. The R2,R5,R6 cloud
is the 141.41.26.0/24 network. The R5/R4 P2P is the 141.141.45.0/24 network.

I have full ip reachability, all my routing is working fine and I run into
this IOS services task.

R4 has an ethernet interface on the 141.141.200.0/24 subnet. R6, which is on
the other end of the frame-relay cloud from R4 has an ethernet interface on
the 141.41.67.0/24 subnet. The task requires that you configure R4 to be a
DHCP server to hand out addresses on the 141.41.67.0/24 subnet. In other
words, you need a helper address on R6's ethernet. In order to verify your
configuration, you need to bring up R8's ethernet interface and set it for
dhcp.

Here is where it gets weird. On R6 I have the following frame mappings as
you would expect of a spoke: A static mapping to the hub, the other spoke,
and itself.

R6(config-if)#do sh frame map
Serial2/0 (up): ip 141.41.26.2 dlci 602(0x25A,0x94A0), static, broadcast,
CISCO, status defined, active Serial2/0 (up): ip 141.41.26.5 dlci
602(0x25A,0x94A0), static, CISCO, status defined, active Serial2/0 (up): ip
141.41.26.6 dlci 602(0x25A,0x94A0), static, CISCO, status defined, active

After I have everything setup, R8 is not pulling a DHCP address, so I turn
on some debugging and see this:

..Jan 23 07:52:32.443: IP: s=0.0.0.0 (Ethernet0/0), d=255.255.255.255, len
604, rcvd 2 ..Jan 23 07:52:32.443: UDP src=68, dst=67 ..Jan 23 07:52:32.443:
IP: s=141.41.67.6 (local), d=4.4.4.4 (Serial2/0), len 604, sending ..Jan 23
07:52:32.443: UDP src=67, dst=67 ..Jan 23 07:52:32.447: IP: s=141.41.67.6
(local), d=4.4.4.4 (Serial2/0), len 604, encapsulation failed ..Jan 23
07:52:32.447: UDP src=67, dst=67

So, I see the DHCP broadcast come in from R8, thats good. Then I see R6
attempt to unicast to R4 because it has ip helper-address 4.4.4.4 configured
(R4's loopback) so thats good ....... and then boom encapsulation failed.
First off I don't understand why this is happening. I have a route to
4.4.4.4, which R6 learnes via ospf from R5 from across the frame. I would
think that like ANY other route it has that it would first lookup 4.4.4.4 in
the routing table, see that the next hop is 141.41.26.5, then send the
packet source 141.41.67.6 , destination 4.4.4.4 with a DLCI of 602 as it is
destined for R5. Here is the route entry on R6.

Routing entry for 4.4.4.4/32
Known via "ospf 1", distance 110, metric 20, type extern 2, forward metric
64
Redistributing via eigrp 679
Advertised by eigrp 679 metric 1 1 1 1 1 Last update from 141.41.26.5 on
Serial2/0, 01:37:43 ago Routing Descriptor Blocks:
* 141.41.26.5, from 5.5.5.5, 01:37:43 ago, via Serial2/0 Route metric is 20,
traffic share count is 1

No, here is the really insane part! If I change absolutely NOTHING and ping
4.4.4.4 from R6 it works just fine. If I ping ANY other route in my lab
network, it works just fine. I am stumped, hoping for some help!
Here is the first packet sent, and first received: So why is it that if I
send an icmp packet it works, but if I send a UDP packet to the exact same
ip address it fails encapsulation? FYI there are no ACLs or filtering
involved. Also if I do a frame map to 141.141.45.4 out DLCI 602 it works. I
just don't get why I would need that at all, since as I said above I think
it should recursively look up the route, and send it out the proper DLCI to
the next hop address.

R6(config-if)#do ping 4.4.4.4

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!
..Jan 23 07:57:37.352: IP: tableid=0, s=141.41.26.6 (local), d=4.4.4.4
(Serial2/0), routed via FIB ..Jan 23 07:57:37.352: IP: s=141.41.26.6
(local), d=4.4.4.4 (Serial2/0), len 100, sending ..Jan 23 07:57:37.352: ICMP
type=8, code=0 ..Jan 23 07:57:37.548: IP: tableid=0, s=4.4.4.4 (Serial2/0),
d=141.41.26.6 (Serial2/0), routed via RIB ..Jan 23 07:57:37.548: IP:
s=4.4.4.4 (Serial2/0), d=141.41.26.6 (Serial2/0), len 100, rcvd 3 ..Jan 23
07:57:37.548: ICMP type=0, code=0

Thanks for ANY help on this one!

- Joe

Blogs and organic groups at http://www.ccie.net

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