Monday, September 10, 2018

BGP Prefix maxed out and peer status issue?

XR-RT1 Configuration:

if maximum-prefix 1,000,000 for both 1.1.1.2 & 2.2.2.2 peer.

XR-RT1#

Neighbor Spk AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down St/PfxRcd

1.1.1.20 650 2515237175 772012 0 0 0 03:16:28 Idle (PfxCt)

2.2.2.20 650 2506061347 772024 0 0 0 03:16:25 Idle (PfxCt)

XE-RT1#sh ip bgp summary

1.1.1.1 4 650 0 0 1 0 0 1y24w Idle

XE-RT2#sh ip bgp summary

1.1.1.1 4 650 0 0 1 0 0 30w2d Idle

XR-RT1 Logs:

RP/0/RSP0/CPU0: : bgp[1049]: %ROUTING-BGP-5-MAXPFX : No. of IPv6 Labeled-unicast prefixes received from 1.1.1.1 has reached 98305, max 131072

RP/0/RSP0/CPU0: : bgp[1049]: %ROUTING-BGP-5-ADJCHANGE_DETAIL : neighbor 1.1.1.1 Down - Peer exceeding maximum prefix limit (CEASE notification sent - maximum number of prefixes reached) (VRF: default; AFI/SAFI: 1/1, 2/4) (AS: 650)

XE-RT1 Logs:

%BGP_SESSION-5-ADJCHANGE: neighbor 1.1.1.1 IPv6 Unicast topology base removed from session Peer closed the session

%BGP_SESSION-5-ADJCHANGE: neighbor 1.1.1.1 IPv4 Unicast topology base removed from session Peer closed the session

Topological:

----------- XE-RT1

XR-RT1

----------- XE-RT2

ISSUE: XR-RT1 detects that the prefix limit has been reached out and due to exceeding prefix limit, BGP went down.

Question:

  1. Why does logs shows "from 1.1.1.1 has reached 98305, max 131072" while my maximum-prefix allowed was up 1million?

  2. How to pin point the cause of the maxed-out issue?

  3. Noticed that when prefix maxed out issue occured XE's BRG "up/down time" is not similar with the XR or not been reset (shows that its idle for along time)?

  4. Seems like logs from XR and XE doenst match (XR only ipv6 logs while XE shows IPV4/IPV6)?

Thank you



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