06-02-2009 03:09 AM - edited 03-04-2019 04:57 AM
Hello GS,
Please help me in the below scenario.
I have a 100mb link configured with BGP and 2MB link configured with Eigrp.
Scenario1:- Since 100mb is a big BW, I want the return traffic also to come from the same BGP 100 mb link.
Scenario2:- In few cases I observed few destinations are going via BGP link and fe via Eigrp link.
Below is configuration and trace route report:-
MUHC WAN Router:-
interface GigabitEthernet0/0
description To Internal LAN Network Ghussais
ip address 10.121.254.1 255.255.255.0
duplex auto
speed auto
interface GigabitEthernet0/1
description TO IP_CONNECT MPLS - 123456
ip address 10.241.121.1 255.255.255.252
duplex auto
speed auto
interface BRI0/0/0
no ip address
encapsulation hdlc
shutdown
interface Serial0/1/0
description 2 mbps LL to HQ - 1234567
bandwidth 2000
ip address 10.240.121.2 255.255.255.252
encapsulation ppp
router eigrp 1
network 10.121.0.0 0.0.255.255
network 10.240.121.0 0.0.0.255
network 10.241.121.0 0.0.0.255
no auto-summary
router bgp 121
bgp log-neighbor-changes
neighbor 10.241.121.2 remote-as 64517
!
address-family ipv4
neighbor 10.241.121.2 activate
no auto-summary
no synchronization
network 10.121.0.0 mask 255.255.0.0
exit-address-family
!
ip route 0.0.0.0 0.0.0.0 10.240.121.1
ip route 10.1.0.0 255.255.0.0 10.240.121.1
ip route 10.121.0.0 255.255.0.0 10.121.254.2
Branch office - MUHC2851-Router# traceroute 10.1.254.1 ( Head office IP)
Type escape sequence to abort.
Tracing the route to 10.1.254.1
1 10.240.121.1 64 msec 80 msec 8 msec
2 10.1.250.1 12 msec 648 msec 108 msec
Branch office - MUHC2851-Router# traceroute 10.15.254.1 ( another BO IP)
Type escape sequence to abort.
Tracing the route to 10.15.254.1
1 10.240.121.1 8 msec 16 msec 180 msec
2 10.1.250.200 544 msec 20 msec 24 msec
3 10.240.16.2 104 msec 624 msec 120 msec
4 10.15.250.1 216 msec 64 msec *
Branch office - MUHC2851-Router# traceroute 10.8.254.1 ( another BO IP)
Type escape sequence to abort.
Tracing the route to 10.8.254.1
1 10.241.121.2 4 msec 0 msec 0 msec - ----- please look at HOP1
2 * * *
3 10.241.8.1 [AS 64517] 0 msec 0 msec 0 msec
4 10.8.251.2 [AS 8] 4 msec 0 msec 4 msec
5 10.8.254.253 [AS 8] 4 msec 0 msec *
Branch office - MUHC2851-Router# traceroute 10.44.254.1
Type escape sequence to abort.
Tracing the route to 10.44.254.1
1 10.240.121.1 8 msec 12 msec 20 msec ----- please look at HOP1
2 10.1.250.1 12 msec 8 msec 8 msec
3 10.43.250.33 [AS 43] 8 msec 8 msec *
+++++++++++++++++++++++++++++++++++++++
MUHC -Core switch:
interface Vlan252
ip address 10.121.252.1 255.255.255.0
interface Vlan254
ip address 10.121.254.2 255.255.255.0
router eigrp 1
network 10.121.3.0 0.0.0.255
network 10.121.10.0 0.0.0.255
network 10.121.50.0 0.0.0.255
network 10.121.101.0 0.0.0.255
network 10.121.102.0 0.0.0.255
network 10.121.103.0 0.0.0.255
network 10.121.201.0 0.0.0.255
network 10.121.202.0 0.0.0.255
network 10.121.252.0 0.0.0.255
network 10.121.253.0 0.0.0.255
network 10.121.254.0 0.0.0.255
network 10.121.0.0 0.0.255.255
no auto-summary
+++++++++++++++++++++++++++++++++++++++++++
Return Traffic from otherBranch office & HQ locations to MUHC BO :-
TUHC_6513_CS1 IP_10.44.254.1#traceroute 10.121.254.1 ( MUHC BO IP)
Type escape sequence to abort.
Tracing the route to 10.121.254.1
1 10.43.250.34 0 msec 0 msec 0 msec
2 10.1.250.50 [AS 1] 0 msec 0 msec 0 msec
3 10.240.121.2 12 msec * 20 msec
DUHC_6509_CS1_10.8.254.1#traceroute 10.121.254.1 ( MUHC BO IP)
Type escape sequence to abort.
Tracing the route to 10.121.254.1
1 10.8.250.1 0 msec 0 msec 0 msec
2 10.240.8.1 12 msec 16 msec 16 msec
3 10.1.250.50 16 msec 8 msec 8 msec
4 10.240.121.2 8 msec * 4 msec
HQ_6513_CS1_10.1.254.1#traceroute 10.121.254.1
Type escape sequence to abort.
Tracing the route to 10.121.254.1
1 10.1.250.50 0 msec 0 msec 0 msec
2 10.240.121.2 8 msec * 8 msec
Thanks in advance,
Mirza.
Solved! Go to Solution.
06-02-2009 09:27 PM
Hello Mirza,
>> If i does summarization in Eigrp does it works when my BGP link goes down?
yes exactly as the BGP aggregate
>> Assume if i only publish router summarization in EIGRP and BGP then route selection wil be done on AD vlaue?
yes with eBGP preferred over normal EIGRP routes, some tuning is needed for EIGRP summary routes (lowest is better eBGP AD=20 EIGRP AD=90: note EIGRP summary route have AD 5 you may need to add an AD greater then 20 at the end of the ip summary-address eigrp interface command; )
>> basically i am looking to avoid typing so many more specific routes in BGP
to avoid this you can redistribute EIGRP into BGP at WAN HQ router
Hope to help
Giuseppe
06-02-2009 03:12 AM
Further info is at MUHC
BGPlink subnett is 10.241.121.0
Eigrp link subnett is 10.240.121.0.
I see abnormality in return traffic and also forwarding traffic.
06-02-2009 04:58 AM
Hello Mirza,
the WAN router is advertising net 10.121.0.0/16 in eBGP to branch office.
Be aware that the most specific prefix is used regardless of Administrative distance.
So if branch office receives more specific routes from another path via EIGRP it will use it.
To achieve the desired behaviuor you can do
use ip eigrp summary address to have only 10.121.0.0/16 advertised to branch office in EIGRP
Edit:
it has to be used on an interface on the path to branch office
OR
you need to advertise all the detailed routes in eBGP
you can achieve this with on the WAN router with:
router bgp 121
address-family ipv4 unicast
redistribute eigrp
Hope to help
Giuseppe
06-02-2009 07:50 PM
HEllo Giuseppe ,
Thank you for the nice explanation.
If i does summarization in Eigrp does it works when my BGP link goes down?
Do i need to publish all my more specific routers in BGP .
Assume if i only publish router summarization in EIGRP and BGP then route selection wil be done on AD vlaue?
basically i am looking to avoid typing so many more specific routes in BGP .
any scenario or link for the more explantion.
once again thanks for your explanation.
Regards,
Mirza.
06-02-2009 09:27 PM
Hello Mirza,
>> If i does summarization in Eigrp does it works when my BGP link goes down?
yes exactly as the BGP aggregate
>> Assume if i only publish router summarization in EIGRP and BGP then route selection wil be done on AD vlaue?
yes with eBGP preferred over normal EIGRP routes, some tuning is needed for EIGRP summary routes (lowest is better eBGP AD=20 EIGRP AD=90: note EIGRP summary route have AD 5 you may need to add an AD greater then 20 at the end of the ip summary-address eigrp interface command; )
>> basically i am looking to avoid typing so many more specific routes in BGP
to avoid this you can redistribute EIGRP into BGP at WAN HQ router
Hope to help
Giuseppe
06-03-2009 12:06 AM
Hello Giuseppe ,
Thanks you so much for the gr8 explanation.
Let me follow these instructions at my locations and see the results today.
Thanks, Mirza.
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