EIGRP neighbor fails over BGP

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Jul 2nd, 2009
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I have 10 Mbps link from service provider ,( BGP is running by ISP).We have eigrp between location but as bandwidth utilization goes beyond 10 Mb eigrp session expired.i tried QOS for eigrp with reserve bandwidth of 1 Mb but it is not working.We have eigrp over tunnel.

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Overall Rating: 5 (1 ratings)
Edison Ortiz Thu, 07/02/2009 - 05:58
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Your approach on using QoS was a sound one but you aren't going to match any EIGRP traffic via the physical interface. As you mentioned the EIGRP is active on the GRE tunnel, not the physical interface so that interface will just see the GRE payload.

You may need to use QoS pre-classify on the tunnel and mark traffic on that tunnel with a DSCP value.

At the physical interface, you can apply an outbound service-policy to match on that DSCP and reserve the necessary bandwidth.




gajanangavli Thu, 07/02/2009 - 06:23
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Hi Edison,

Thanks for suggest , kindly find the below config on router.

Tunnel for eigrp

interface Tunnel1

description **Tunnel 10Mbps **

bandwidth 10000

ip address a.b.c.d

ip tcp adjust-mss 1380

load-interval 30

delay 10

qos pre-classify

keepalive 10 3

tunnel source x.x.x.x

tunnel destination Y.Y.Y.Y


Physical interface on which policy is applied

interface FastEthernet2/0

description ** -10Mbps **

ip address x.x.x.x

no ip redirects

no ip unreachables

ip flow ingress

ip flow egress

no ip mroute-cache

load-interval 30

service-policy output VOICE-EF-SIG


Extended IP access list EIGRP-QOS

10 permit eigrp any host (7893 matches)

20 permit eigrp any host Tunnel source IP

30 permit eigrp any host tUNNEL DESTINATION IP (3934 matches)

40 permit eigrp any any dscp cs6 (3720 matches)

class-map match-all EIGRP-QOS

match access-group name EIGRP-QOS


Bandwidth 1024 (kbps) Max Threshold 64 (packets)



Strict Priority

Bandwidth 2048 (kbps) Burst 51200 (Bytes)


Bandwidth 50 (kbps) Max Threshold 64 (packets)


Bandwidth 2048 (kbps) Max Threshold 64 (packets)

Class Class-HPOV

Bandwidth 2048 (kbps) Max Threshold 64 (packets)


Bandwidth 1024 (kbps) Max Threshold 64 (packets)

Is there anything to do further for avoiding eigrp neighbor disconnection due to bandiwidth issue over BGP ?

Edison Ortiz Thu, 07/02/2009 - 07:06
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Did you apply those changes now or were they implemented before?

Looks good.

Another issue you may be running is if your router is overloaded due to the high traffic and it's dropping packets. Check your CPU and make sure it is not hitting 100% for a long period of time.

Also, check the class EIGRP-QOS for packet drops within that class as well as interface level output drops.

Additionally, your ISP may be enforcing a policer once you hit 10Mbps and it may be dropping all traffic. You may want to shape outbound to a value less than 10Mbps to avoid drops.




gajanangavli Thu, 07/02/2009 - 20:11
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Thanks for your valuable suggestion.

1)changes done before( Starting discussion)

2)This is 7200 se router , dont have issue of CPU utilization

3)No drops found in class map

Class-map: EIGRP-QOS (match-all)

17402 packets, 3651310 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: access-group name EIGRP-QOS


Output Queue: Conversation 268

Bandwidth 1024 (kbps)Max Threshold 64 (packets)

(pkts matched/bytes matched) 3934/2331446

(depth/total drops/no-buffer drops) 0/0/0

4)Service provider policing traffic , more than 10 Mbps we are getting drop that is root cause of breaking eigrp seesion.

BGP is not serious about eigrp ( hello,update) packet.

Edison Ortiz Fri, 07/03/2009 - 08:11
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To reiterate, configure a hierarchical QoS with a parent shaper of 9.5Mbps or 9Mbps to prevent the Service Provider's policer.




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