08-07-2011 10:39 PM - edited 03-04-2019 01:12 PM
Hello,
I have one scenario. One end is using Cisco router and the other end using Juniper router have been configured eBGP Multihoming using loopback IP. At each router, two interface have been configured and both static route has been pointing to the eBGP loopback IP. The problem is, for example if the
1st interface/link down, the BGP also will down eventhough the 2nd interface/link up. By right for Multihoming BGP at least one physical link should be up to keep to BGP up. Any one have experienced this sort of problem before? Need some help. Thanks in advance!
Regards,
arel
08-07-2011 11:13 PM
Having a look at some configuration would be helpful.
Cisco side should contain this:
neighbor 2.2.2.2 remote-as xxxx
neighbor 2.2.2.2 update-source loopback 0
neighbor 2.2.2.2 ebgp-multihop [ttl]
Are you sure both paths are working?
Verify both paths carefully, using static routes may not be the best way to create failover redundancy.
regards,
Leo
08-07-2011 11:59 PM
Hi Leo,
Thanks a lot for your feedback. Both path are working and all configuration you mention above already included. Please look example config below. If one link down the BGP will drop. Any idea what cause this problem? Thank you
----------------------------
CISCO BGP config
----------------------------
neighbor 2.2.2.2 remote-as xx
neighbor 2.2.2.2 description "SINGA-STM4x2"
neighbor 2.2.2.2 ebgp-multihop 2
neighbor 2.2.2.2 password 7 xxxxxx
neighbor 2.2.2.2update-source Loopback0
neighbor 2.2.2.2 activate
neighbor 2.2.2.2 remove-private-as
neighbor 2.2.2.2 soft-reconfiguration inbound
neighbor 2.2.2.2 prefix-list in-filter in
neighbor 2.2.2.2 prefix-list xxxxxx out
neighbor 2.2.2.2 route-map xxxxx in
neighbor 2.2.2.2 filter-list 1 out
ip route 2.2.2.2 255.255.255.255 x.x.x.33
ip route 2.2.2.2 255.255.255.255 x.x.x.21
Loopback0 1.1.1.1
Juniper BGP config
==============
set routing-options static route 1.1.1.1/32 next-hop x.x.x.22
set routing-options static route 1.1.1.1/32 next-hop x.x.x.34
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 descriptionn "XXXX with Multihop-EBGP"
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 multihop ttl 2
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 local-address 2.2.2.2
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 import no-default
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 import no-smallprefixes
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 import rfc1918-dsua
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 import XXXXIN
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 import XXX-IN
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 family inet any prefix-limit maximum 1000
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 family inet any prefix-limit teardown 90
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 family inet any prefix-limit teardown idle-timeout forever
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 authentication-key "xxxxxx"
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 export no-default
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 export no-smallprefixes
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 export rfc1918-dsua
set protocols bgp group CUSTOMERS neighbor 1.1.1.1 peer-as XXXX
Regards,
arel
08-08-2011 12:44 AM
Hi,
What type of WAN link are you using?
Regards.
Alain.
08-08-2011 12:55 AM
Hi Alain,
Do you mean interface? POS interface. Thanks
Regards,
arel
08-08-2011 01:00 AM
Yes and what encapsulation are you using?
Regards.
Alain.
08-08-2011 01:09 AM
encapsulation PPP
Regards,
arel
08-08-2011 01:42 AM
Hi,
Can you post output of sh ip route static and sh ip int br | exc una when both links are up then when one is down
as well as sh run interface.
Regards.
Alain.
08-08-2011 02:04 AM
Gentlemen,
In addition to other requested information, would it be possible to post the (complete) output of the show ip bgp neighbor 2.2.2.2 command on the Cisco side?
Best regards,
Peter
08-08-2011 03:21 AM
Hi Guys,
Maybe later will do some failover test and capture debugging for both router to check BGP and TCP transaction. I think there is no wrong with the configuration right or am I missing any configuration? because when both links is up no issue arise...
==================
Cisco interface config
==================
interface POS7/1
description XXXXX
ip address X.X.X.22 255.255.255.252
no ip directed-broadcast
encapsulation ppp
ip route-cache flow sampled input
crc 32
pos framing sdh
pos flag s1s0 2
!
interface POS7/2
description XXXX
ip address X.X.X.34 255.255.255.252
no ip directed-broadcast
encapsulation ppp
ip route-cache flow sampled input
crc 32
pos framing sdh
pos flag s1s0 2
!
=====
Juniper
======
- configuration is the same for other interface
> show configuration interfaces so-6/1/1
clocking external;
encapsulation ppp;
sonet-options {
fcs 32;
no-payload-scrambler;
}
unit 0 {
description "XXXXX"
family inet {
rpf-check {
fail-filter URPF-FILTER;
mode loose;
}
filter {
input CFLOW;
}
address x.x.x.21/30;
}
}
Regards,
Arel
08-08-2011 10:39 AM
i'm just curious..erm could be this related to problem at lower layer? example on transmission issue?
Regards,
arel
08-08-2011 11:01 AM
Hi,.
I think it's hard to answer without further info
But your config is good for Cisco and AFAIK on the Juniper side also.
Were you able to ping 2.2.2.2 from 1.1.1.1 when the failover occured and the BGP peering went down?
Regards.
Alain.
08-08-2011 11:37 AM
Hi Alain,
When one interface down,one interface up while BGP was down..ping to BGP neighbor was reach able. Thank you
08-08-2011 10:17 PM
i would also do a debug on the Juniper..i have seen things on a Juniper that are not so pretty..
Also do a deug for PPP, you never know it may prove something.
hth
08-08-2011 11:52 PM
Hi,
rpf-check {
fail-filter URPF-FILTER;
mode loose;
}
filter {
input CFLOW;
Isn't it an ACL ? along with uRPF could it be the culprit?
Regards.
Alain.
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