Hi Sam,

thanks for reply so when router receives update from Telco router that can cause the router not reachable at that time?

No that should not happen!

What might have happened is that your router lost connectivity to peer router, but BGP did not react as it takes a default 3 missed hellos before session is noted as down.

during 180s, traffic can basically be blackholed.

Sam

Hi sam,

her eis detail nei info

sh ip bgp nei

BGP neighbor is 10.70.12.13, remote AS 64543, external link

Description: "eBGP to AT&T CE Router"

BGP version 4, remote router ID 135.42.95.211

BGP state = Established, up for 5w0d

Last read 00:00:13, last write 00:00:07, hold time is 45, keepalive interval is 15 seconds

Configured hold time is 45,keepalive interval is 15 seconds, Minimum holdtime from neighbor is 0 seconds

Neighbor capabilities:

Route refresh: advertised and received(old & new)

Address family IPv4 Unicast: advertised and received

Message statistics:

InQ depth is 0

OutQ depth is 0

Sent Rcvd

Opens: 5 5

Notifications: 0 0

Updates: 100 188570

Keepalives: 5000726 5000711

Route Refresh: 18 2

Total: 5000849 5189287

Default minimum time between advertisement runs is 30 seconds

For address family: IPv4 Unicast

BGP table version 614690, neighbor version 614690/0

Output queue size : 0

Index 2, Offset 0, Mask 0x4

2 update-group member

Community attribute sent to this neighbor

Inbound path policy configured

Outbound path policy configured

Route map for incoming advertisements is MPLS_IN

Route map for outgoing advertisements is ATT_OUT

Sent Rcvd

Prefix activity: ---- ----

Prefixes Current: 6 1619 (Consumes 84188 bytes)

Prefixes Total: 12 12187

Implicit Withdraw: 6 7565

Explicit Withdraw: 0 3003

Used as bestpath: n/a 1617

Used as multipath: n/a 0

Outbound Inbound

Local Policy Denied Prefixes: -------- -------

route-map: 10708 0

Suppressed duplicate: 0 1639

AS_PATH loop: n/a 18

Total: 10708 1657

Number of NLRIs in the update sent: max 0, min 0

Connections established 5; dropped 4

Last reset 5w1d, due to Interface flap

Connection state is ESTAB, I/O status: 1, unread input bytes: 0

Connection is ECN Disabled

Local host: 10.70.12.14, Local port: 179

Foreign host: 10.70.12.13, Foreign port: 51423

Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)

Event Timers (current time is 0x117913F2A4):

Timer Starts Wakeups Next

Retrans 206239 9 0x0

TimeWait 0 0 0x0

AckHold 209874 202255 0x0

SendWnd 0 0 0x0

KeepAlive 0 0 0x0

GiveUp 0 0 0x0

PmtuAger 0 0 0x0

DeadWait 0 0 0x0

iss: 2792573695 snduna: 2796492375 sndnxt: 2796492375 sndwnd: 15624

irs: 2691793629 rcvnxt: 2696045834 rcvwnd: 15453 delrcvwnd: 931

SRTT: 300 ms, RTTO: 303 ms, RTV: 3 ms, KRTT: 0 ms

minRTT: 0 ms, maxRTT: 636 ms, ACK hold: 200 ms

Flags: passive open, nagle, gen tcbs

IP Precedence value : 6

Datagrams (max data segment is 1460 bytes):

Rcvd: 408298 (out of order: 0), with data: 210105, total data bytes: 4252204

Sent: 411394 (retransmit: 9, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data: 206229, total data bytes: 3918679

so in this case it wil wait 45 secs before thinking that nei is down right?

many thanks

Correct !

Configured hold time is 45,keepalive interval is 15 seconds

check ur logs to see if there are any outages of short time.

Hi sam

there are no outages

here is logs

May 16 04:36:03.551 extende: %SYS-5-CONFIG_I: Configured from console by e430822 on vty0 (10.169.207.55)

May 18 09:02:19.432 extende: %SYS-5-CONFIG_I: Configured from console by e414921 on vty0 (10.164.43.34)

NCIFDSCL01B# sh clock

07:23:09.971 extended_DST Sun May 31 2009

NCIFDSCL01B#

Hi sam

thanks for quick reply.

nei is AT & T mpls ce router.so something might have happened in AT & T

cloud then?

also cpu is normal i checked it.so high cpu can also be cause of lost of connectivity to router?

Mahesh

I do not see anything that tells us how you were attempting to access your router when it was not accessible. Unless you were outside somewhere and your path to the router was through AT&T, it is not likely that something happening with that neighbor would impact your ability to access the router.

When you had the problem and could not access the router, did you try to ping the router? A ping to the router would help determine whether the problem was about reachability to the router or whether it was some problem on the router.

HTH

Rick

Hi rick,

thanks for reply.

i try to ping the router but it was not reachable.after few mins i was able to login to router.

Mahesh

It is helpful to know this. Where were you (what was your source address) and what was the path that should get you to the router (were you coming from outside to it or from inside to it)?

HTH

Rick

Hi rick,

i try to ping from nei router source IP

10.70.12.2 and i try to ping destination IP 10.70.12.3.also i try to ping from this source IP 155.108.251.1 and from here also ping did not work.

Mahesh

In a previous post you provided this information for the AT&T neighbor:

Local host: 10.70.12.14, Local port: 179

Foreign host: 10.70.12.13, Foreign port: 51423

So it is correct the the interface address on your router connected to AT&T is 10.70.12.14 and that the AT&T router has address 10.70.12.13? If that is the case and if you were at 10.70.12.2 and attenpted to access 10.70.12.3, then how does the AT&T router affect this access since neither of these addresses match where you are or what you are attempting to access?

HTH

Rick