08-07-2009 08:55 AM - edited 03-04-2019 05:41 AM
I am perplexed. My router is choosing the slow conneciton over the fast connection for EIGRP routes.
This is a dual hub and spoke design, with all the sites having a full T1 to the main (all via S0/0/0.1) and only 256k to the backup (all via the S0/0/0.2). For spoke site A to talk to spoke site B, it would either use two T1 links through the main hub or two 256k links through the backup hub.
Here is my setup (IPs have been changed):
interface Serial0/0/0.1 point-to-point
bandwidth 1544
ip address 1.1.1.1 255.255.255.252
ip nbar protocol-discovery
ip policy route-map nachi
frame-relay interface-dlci 16
!
interface Serial0/0/0.2 point-to-point
bandwidth 256
ip address 2.2.2.2 255.255.255.252
ip bandwidth-percent eigrp 1 10
ip policy route-map nachi
no cdp enable
frame-relay interface-dlci 20
!
router eigrp 1
redistribute connected
redistribute static
passive-interface GigabitEthernet0/0
passive-interface GigabitEthernet0/1
network 1.1.1.0 0.0.0.255
network 2.2.2.0 0.0.0.255
no auto-summary
no eigrp log-neighbor-changes
neighbor 1.1.1.2 Serial0/0/0.1
neighbor 2.2.2.2 Serial0/0/0.2
!
route-map nachi permit 10
match ip address 2003
match length 92 92
set interface Null0
#show ip eigrp nei
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 1.1.1.2 Se0/0/0.1 14 00:00:22 1244 5000 3 547766
0 2.2.2.2 Se0/0/0.2 10 00:04:51 32 2850 0 408246
#show ip eigrp top
IP-EIGRP Topology Table for AS(1)/ID(1.1.1.1)
P 0.0.0.0/0, 1 successors, FD is 10516992
via 2.2.2.2 (10516992/61952), Serial0/0/0.2
P 3.3.3.0/30, 1 successors, FD is 11023872
via 2.2.2.2 (11023872/10511872), Serial0/0/0.2
HELP!
Solved! Go to Solution.
08-10-2009 12:15 AM
Hi
I suspect this can be a mtu issue.
I would recomend you to set the mtu size to 1500 on the atm side.
/Mikael
08-07-2009 08:59 AM
Try setting the delay on the 256k lines higher than that of the T1s. The bandwidth setting should be taken into consideration when eigrp does it's calculation, but Cisco recommends tuning the delay parameters first.
HTH,
John
08-07-2009 09:16 AM
I kept the delay of the T1 at 20,000 (default) and increased the delay of the 256k connection to 100,000 and there was no change.
08-07-2009 09:03 AM
Based on the EIGRP Nei output the 'Q' count on neighbor 1.1.1.1 is 3 which means there are 3 pending updates on this link.
The 'Q' count should be '0' thus I suggest inspecting the link for errors and such.
HTH,
__
Edison.
08-07-2009 09:07 AM
Inspecting the link for errors, as in Layer 1 and 2 errors, or configuation errors?
08-07-2009 09:10 AM
Based on the config portion you've posted, I don't see a configuration issue. Can you post the remote site config?
08-07-2009 09:14 AM
Edison,
Just throwing this out there since I'm trying to learn from this problem as well. Would putting a delay statement under his 256k link higher than his T1 fix the problem if the other side doesn't have any errors in the config either? I had seen that you said there were pending updates that were in the queue, so if that wasn't the problem would delay fix it?
Thanks,
John
08-07-2009 09:25 AM
Delay as well as bandwidth are part of the EIGRP metric calculation but it will not help any L1 L2 issues that are currently present as packets aren't leaving the interface in the correct manner.
He already has the bandwidth information so EIGRP will choose the higher bandwidth interface. You can use delay if you didn't want to use the bandwidth as part of the metric, IOW if bandwidth were equal but that's not the case here.
__
Edison.
08-07-2009 09:54 AM
What I notice is that the show ip eigrp topology only shows entries from one neighbor. I wonder what we would get if Michael would post the output of show ip eigrp topology all. Perhaps that will clarify what is going on. I wonder if advertisements from the T1 neighbor are getting through.
HTH
Rick
08-07-2009 09:23 AM
Main Hub Site:
vc-class atm atm
vbr-nrt 30000 15000 256
!
vc-class atm Remote-1708-1708
vbr-nrt 1708 1708 32
!
interface ATM1/0
no ip address
ip route-cache flow
ip ospf priority 0
ip policy route-map nachi
class-int atm
atm scrambling cell-payload
atm framing cbitplcp
no atm auto-configuration
no atm ilmi-keepalive
!
interface ATM1/0.68 point-to-point
description Connection to messed up spoke site
bandwidth 1708
ip address 1.1.1.2 255.255.255.252
ip nbar protocol-discovery
ip bandwidth-percent eigrp 1 10
ip policy route-map nachi
pvc 3/68
class-vc Remote-1708-1708
vc-hold-queue 300
oam-pvc 0
!
router eigrp 1
redistribute connected
redistribute static
passive-interface FastEthernet0/0
passive-interface FastEthernet0/1
network 1.1.1.0 0.0.0.255
neighbor 1.1.1.1 ATM1/0.68
no auto-summary
08-07-2009 09:30 AM
ATM to Serial? ugh. I suspect L1 L2 problems. Contact the provider. You also listed some input errors on the remote serial so...
08-07-2009 10:01 AM
TY, I am opening up a case with them now and will post the results.
08-07-2009 09:04 AM
I did a clear ip eigrp nei and grabbed a debug of the output. Here is part of it:
IP-EIGRP Route Events debugging is on
NEVC_2821#terminal monitor
NEVC_2821#clear ip eigrp 1 neighbors
NEVC_2821#
Aug 7 12:18:03.926 EDT: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE packet
Aug 7 12:18:03.978 EDT: IP-EIGRP(Default-IP-Routing-Table:1): A.A.A.0/25 - do advertise out Serial0/0/0.2
Aug 7 12:18:03.978 EDT: IP-EIGRP(Default-IP-Routing-Table:1): Ext A.A.A.0/25 metric 28160 - 25600 2560
Aug 7 12:18:04.018 EDT: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE packet
Aug 7 12:18:04.018 EDT: IP-EIGRP(Default-IP-Routing-Table:1): Int F.F.F.F/30 M 40516864 - 40000000 516864 SM 6169
6 - 56832 4864
Aug 7 12:18:04.018 EDT: IP-EIGRP(Default-IP-Routing-Table:1): route installed for F.F.F.F ()
...truncated...
Aug 7 12:18:04.749 EDT: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE packet
Aug 7 12:18:04.757 EDT: IP-EIGRP(Default-IP-Routing-Table:1): A.A.A.0/25 - do advertise out Serial0/0/0.1
Aug 7 12:18:04.757 EDT: IP-EIGRP(Default-IP-Routing-Table:1): Ext A.A.A.0/25 metric 28160 - 25600 2560
...truncated...
Aug 7 12:20:47.310 EDT: IP-EIGRP(Default-IP-Routing-Table:1): ExtS A.A.A.0/25 M 4294967295 - 9999872 4294967295 S
M 4294967295 - 9999872 4294967295
...truncated...
08-07-2009 09:17 AM
Additional background info:
First started looking because site complained of slowness. I am using a netflow collector and saw that the site's incoming traffic was from the Main Hub site as expected, but all outgoing traffic was to the Backup Hub site.
08-07-2009 09:19 AM
Well, do you see any crc errors or anything on the T1 link?
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