[c-nsp] Can not establish MP-BGP sessions
Andy Saykao
andy.saykao at staff.netspace.net.au
Mon Nov 16 17:48:04 EST 2009
P1=7301 and the other end P2=7606.
The PE's are 7301 running 12.2(31)SB13
Odd thing is that it was all working prior to switching across this our
new switched ethernet circuit.
________________________________
From: Aaron [mailto:dudepron at gmail.com]
Sent: Tuesday, 17 November 2009 3:10 AM
To: Andy Saykao
Cc: Alex; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Can not establish MP-BGP sessions
What is the HW on both ends? Possible one has a bug that is causing
headaches.
On Mon, Nov 16, 2009 at 08:51, Andy Saykao
<andy.saykao at staff.netspace.net.au> wrote:
Hi Alex,
1/ When "mpls ip" is ON on both Gi4/0/1 and Gi0/2 - I can not
ping from
PE2 > PE1 BUT I can ping from PE1 > PE2. That's my real problem
why
MP-BGP won't come up bc I don't seem to have two way comms bt PE
routers' BGP update-source lo99 address.
POP1 [PE1 (lo99:172.16.99.13) --> P1 ] --switched ethernet-->
POP2 [P2
--> PE2 (lo99:172.16.99.4)]
Eg: Ping PE1 > PE2 (OK!)
PE1#ping 172.16.99.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.99.4, timeout is 2
seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max =
8/9/12 ms
Eg: Ping PE2 > PE1 (NOT OK!)
PE2#ping 172.16.99.13
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.99.13, timeout is 2
seconds:
.....
Success rate is 0 percent (0/5)
Ping PE2 > P1 (OK!)
Ping P2 > P1 (OK!)
*** Seems like I can't get any traffic/labels beyond P1 to get
to
PE1.***
Forwarding table entry for PE1(lo99) looks ok on P1.
P1#sh mpls forwarding-table 172.16.99.13 32
Local Outgoing Prefix Bytes Label Outgoing
Next Hop
Label Label or VC or Tunnel Id Switched interface
8668 Pop Label 172.16.99.13/32 158269119 Gi0/0.152
203.17.102.113
2/ When "mpls ip" is ON on both Gi4/0/1 and Gi0/2 - BGP does not
come
up.
PE1#sh ip bgp vpnv4 all summary
BGP router identifier 203.17.101.20, local AS number 4854
BGP table version is 11983, main routing table version 11983
15 network entries using 2115 bytes of memory
15 path entries using 1020 bytes of memory
6/3 BGP path/bestpath attribute entries using 840 bytes of
memory
2 BGP rrinfo entries using 48 bytes of memory
1 BGP AS-PATH entries using 24 bytes of memory
1 BGP community entries using 24 bytes of memory
2 BGP extended community entries using 48 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 4119 total bytes of memory
BGP activity 1539/1500 prefixes, 6326/6263 paths, scan interval
15 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ
Up/Down
State/PfxRcd
172.16.99.4 4 4854 147048 148587 0 0 0
06:48:13
Active
172.16.99.5 4 4854 147196 148642 0 0 0
06:48:08
Active
172.16.99.7 4 4854 147468 148593 0 0 0
06:48:16
Active
172.16.99.9 4 4854 146473 148502 0 0 0
06:48:01
Active
172.16.99.14 4 4854 147066 149123 11983 0 0
10:43:13
7
172.16.99.16 4 4854 146464 148574 0 0 0
06:47:52
Active
172.16.99.19 4 4854 149509 151673 11983 0 0
10:43:59
5
172.16.99.20 4 4854 149448 151672 11983 0 0
10:43:58
2
If I disable "mpls ip" on either Gi4/0/1 and Gi0/2, BGP does
come up but
ofcourse I have no mpls vpn traffic because those links no are
no longer
mpls enabled.
Note that all Active BGP peers are PE devices which sit on the
POP2
side. So all BGP peers on POP1 can establish BGP sessions with
each
other but not to BGP peers at POP2. Like wise PE's at POP2 can
establish
BGP sessions with each other and not with PE's located at POP1.
The forwarding table from PE2 > P2 > P1 looks ok - so not sure
why you
can't ping PE2 > PE1.
PE2#sh mpls forwarding-table 172.16.99.13 32
Local Outgoing Prefix Bytes Label Outgoing
Next Hop
Label Label or VC or Tunnel Id Switched interface
617 3034 172.16.99.13/32 0 Gi0/0.11
203.10.110.211
P2#sh mpls forwarding-table 172.16.99.13 32
Local Outgoing Prefix Bytes Label Outgoing
Next Hop
Label Label or VC or Tunnel Id Switched interface
3034 8668 172.16.99.13/32 1582342 Gi4/0/1
203.17.96.97
P1#sh mpls forwarding-table 172.16.99.13 32
Local Outgoing Prefix Bytes Label Outgoing
Next Hop
Label Label or VC or Tunnel Id Switched interface
8668 Pop Label 172.16.99.13/32 158253163 Gi0/0.152
203.17.102.113
The fact that PE's at POP2 can not communicate with PE's at POP1
is why
I think BGP isn't coming up between PE1 and PE2. I don't know
why mpls
traffic/labels are not being swapped and forwarded beyond P1 to
reach
PE1. MPLS config, ldp, mpls forwarding table and bindings all
look ok to
me - any ideas??? Like I said we haven't changed any config
except
moving from our existing circuit to a new protected switched
ethernet
circuit.
Thanks.
Andy
-----Original Message-----
From: Alex [mailto:ecralar at hotmail.com]
Sent: Monday, 16 November 2009 5:52 PM
To: Andy Saykao; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Can not establish MP-BGP sessions
Hi Andy,
Couple of questions:
1/ Can you ping between PE1 and PE2 _loopbacks_ across the
circuit when
"mpls ip" is ON on both Gi4/0/1 and Gi0/2?
2/ Can you establish BGP session between _interface_ addresses
when
"mpls ip" is ON on both Gi4/0/1 and Gi0/2?
Rgds
Alex
--------------------------------------------------
From: "Andy Saykao" <andy.saykao at staff.netspace.net.au>
Date: 16 November 2009 04:31
To: <cisco-nsp at puck.nether.net>
Subject: [c-nsp] Can not establish MP-BGP sessions
> Hi All,
>
> We migrated a link between two pops onto a Switched Ethernet
circuit
> and since then we can't pass MPLS VPN traffic between those
two pops
> from
> PE1 to PE2 because PE1 and PE2 can not establish a MP-BGP
session.
>
> -------------------------
> BGP log on PE1:
> -------------------------
> Nov 16 14:26:48.693 AEDT: %BGP-5-ADJCHANGE: neighbor
172.16.99.4 Down
> BGP Notification sent Nov 16 14:26:48.693 AEDT:
%BGP-3-NOTIFICATION:
> sent to neighbor
> 172.16.99.4 4/0 (hold time expired) 0 bytes
>
> -------------------------
> Topology:
> -------------------------
> POP1 [PE1 (lo99:172.16.99.13) --- Switched Ethernet --> P1 ]
--> POP2
> [P2 --> PE2 (lo99:172.16.99.4)]
>
> -------------------------
> P1:
> -------------------------
> interface GigabitEthernet4/0/1
> description Connection to P2
> bandwidth 150000
> ip address 203.17.96.x 255.255.255.252 load-interval 30
negotiation
> auto mpls ip
>
> -------------------------
> P2:
> -------------------------
> interface GigabitEthernet0/2
> description Connection to P1
> bandwidth 150000
> ip address 203.17.96.x 255.255.255.252 load-interval 30
media-type
> gbic speed auto duplex auto negotiation auto mpls ip
>
> Interesting thing to note is that if I remove "mpls ip" from
P1's
> interface, the MP-BGP sessions are formed between PE1 and PE2
and stay
> up. When I put "mpls ip" back on the interface, the MP-BGP
session
> times out with the error messgage in the BGP log above.
>
> The only thing that has changed is the introduction of the new
> Switched Ethernet circuit. I was thinking that it might have
something
> to do with jumbo frames but our UpStream Providers tells me
that they
> have configured jumbo frames on either end of the link plus I
can ping
> end from P1 to P2 with byte sizes larger than 8000 bytes.
>
> Has anyone got any ideas as to why the MP-BGP sessions all of
a sudden
> can no longer stay up and what further debug/troubleshooting i
can do?
>
> Thanks.
>
> Andy
>
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