BGP session fail

[dalvi_saad]

Hello guys,

So,I am facing this issue for the past 1 week. I have a p2p Ethernet link  as follow:

PE (Alcatel 7750) ----> SP cloud ----> CE (cisco)

I am able to ping the CE from my PE but not able to form eBGP session between both. As per the SP port 179 is good and not blocked.

The config looks good on both side. There is no MTU issue as I tried to ping with different MTU sizes. No issue with the CE (cisco) since I tried isolation with a test router. No Access list configured on both ends. 

I am posting the PCAP and debug events. Need your valuable inputs.

Note - Please change file ext  from zip to PCAP. 

[Richard Bradfield]

I dont see anything in your PCAP. file only 11KB.

has this ever worked? can you share the BGP config

regards

Richard.

[e.ciollaro]

Hi,

can't open zip file in any case debug is not showing BGP going from idle to connect or anything else, could you post a "sh ip bgp summary" and/or "show ip bgp neigh <pe_address>" ?

Bye,

e

[dalvi_saad]

Hey all,

Seems like some issue with uploading the PCAP file. As I mentioned earlier there is no issue with the config. 

This is ebgp connectiong. The peer IP is pingable.

Telenet to port 179 failed. We tried update-source but was no go. There is no L3 device between PE and CE. TTL is default. There is a IBGP running on the CE

Please find the below config for your reference:

CE:

router bgp 65051
 bgp log-neighbor-changes
 network 10.1.2.49 mask 255.255.255.255
 network 10.234.254.0 mask 255.255.255.0
 network 10.245.3.156 mask 255.255.255.252
 network 192.168.49.0
 network 192.168.250.224 mask 255.255.255.252
 neighbor 10.234.254.10 remote-as 65051
 neighbor 10.245.3.158 remote-as 65000

 ----
 

PE:
    bgp
                group "XXX"
                    prefix-limit 501
                    as-override
                    type external
                    import "xyz-in"
                    export "XYZ-out"
                    peer-as 65000
                    disable-communities extended
                    neighbor 10.245.3.157
                        local-address 10.245.3.158
                    exit
#--------------------------------------------------

CE:
Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.234.254.10   4        65051      30      33       12    0    0 00:26:38        1
10.245.3.158    4        65000       0       0        1    0    0 never    Active

[milan.kulik]

Hi,

shouldn't there be

 peer-as 65051

used instead of 

 peer-as 65000

in your PE config?

See https://infoproducts.alcatel-lucent.com/html/0_add-h-f/93-0074-10-01/7750_SR_OS_Routing_Protocols_Guide/BGP-CLI.html

for details.

Best regards,

Milan

[dalvi_saad]

I am sorry guys my bad, i edited the config incorrectly the correct config is :  

  bgp
                group "XXX"
                    prefix-limit 501
                    as-override
                    type external
                    import "xyz-in"
                    export "XYZ-out"
                    peer-as 65051
                    disable-communities extended
                    neighbor 10.245.3.157
                        local-address 10.245.3.158
                    exit

[dalvi_saad]

Here is the screenshot of the PCAP.

[e.ciollaro]

Hi,

It seems me that TCP 3way handshake is not going properly; I would expect to see SYN - SYN ACK and ACK packets and then the BGP negotiation (BGP Open packet...) as in the attached PCAP. 

In your file I can't see any packet coming back, I think TCP is dropped somewhere in the middle

Bye,

enrico 

[paul driver]

Hello

have you tried the ebgp-multi hop command 

res

paul

[dalvi_saad]

Hey Paul, 

I did try that as well, I am suspecting issue with the provider blocking the 179 port since i was not able to telnet to port 179. But they are saying that they are all good.

[Erico Verissimo]

Hello,

I faced this issue in some year ago. The config are correct and the bgp session do not establish. In my case the PE was Alcatel 7750 e CE cisco 1900. I remember that was a config VPRN on Alcatel that I had change.

Is there VPRN on Alcatel? If there is it, Can you post the config ?

Best Regards

[dalvi_saad]

Hey Erico,

Below is the VPRN config on Alcatel 7750:

 
#--------------------------------------------------
    qos
        sap-egress 1027 create
            description "XYZ_QoS"
#--------------------------------------------------
    service
        vprn 1011100024 customer 1011100024 create
            interface "LAG-10:3016.*" create
                description "ABC"
                sap lag-10:3016.* create
                    description "ABC"
                    egress
                        scheduler-policy "XYZ(10000k/10000k)"

#--------------------------------------------------

   qos
        scheduler-policy "XYZ(10000k/10000k)" create
            description "XYZ_Lag_shaping"
            tier 1
                scheduler "bandwidth" create
                    rate 10000
                exit
            exit

BGP config i have already posted in the thread.

[Erico Verissimo]

Hello,

I remenber that was a config like this:

vprn xxxx customer x create
            autonomous-system (AS NUMBER) - In my case without this line the BGP between PExCE did not established.
            route-distinguisher (RD NUMBER)
            auto-bind ldp (This for MPLS)
            vrf-target export target:xxxx:xxxxx import target:xxxx:xxxxx
            interface "xxxxxxx" create

It is important verify the BGP timers  because there are some difference between devices about the value:

Default Cisco:

Keepalive 60s

Holdtime 180s

Default Alcatel:

Keepalive 30s

Holdtime 90s