BFD is not working with static routes

Static routes are not getting removed

5 replies

Userlevel 4
What software version are you running?
Have you tried to Delete and recreate of static route and then enabling bfd protection?
Let us know the steps which you have followed.
We are running with with patch 1.7 . The BFD mechanism was working fine previously. This upgrade has been done before 150 days. Last week one of our link got fluctuated , but the static routes associated with was not removed from the routing table. In routing table it shows the utime of static routes also 150 days instaed of one week.
Userlevel 4
I saw that you have created the case for similar issue. We will update you shortly on this.
Userlevel 4
For static route, the duration counter will not be reset when the bdf is down. If next hop is not reachable for the static route then bfd would remove “f” flag. “f” flag: Provided to FIB.

On Extreme switch, Static route will always present in routing table. However, we need to concentrate on f flag(FIB entry) and see if that route is actually being used for forwarding.

Swtich will not send traffic to spefic destination if there is route without “f” flag. If we create the multiple static route for same destination then only one route would have entry in FIB(f flag is presnet) and other route doesn’t have “f” flag and entry in FIB. However, we could see the uptime for both route in routing table since the time when we configure it.

Below example shows that we have two route for destination with gateway and Only one route is in FIB(with F flag) and other is not. However, we can still see the duration time for both route.

* SW1.1 # show iproute

Ori Destination Gateway Mtr Flags VLAN Duration

#d 1 U------um--f- test 0d:3h:38m:52s

#s 1 UG---S-um--f- mirrror 0d:0h:9m:54s

#d 1 U------um--f- sumit 0d:3h:38m:52s

#d 1 U------um--f- sumit_test 0d:1h:41m:12s

#oa 14 UG-D---um--f- sumit 0d:1h:21m:0s

#s 1 U----S-um--f- sumit 0d:2h:18m:38s

#s 1 U----S-um---- v1 0d:2h:18m:10s

#d 1 U------um--f- v1 0d:3h:38m:52s

#d 1 U------um--f- mirrror 0d:0h:14m:15s

#d 1 U------um--f- bp 0d:3h:38m:52s

However, if we configure the BFD for OSPF route then you would see the duration timer would get changes according to BFD timer. As those are the dynamic routes.

Establishing a BFD Session for OSPF Neighbor

1 OSPF discovers a neighbor.

2 If BFD for OSPF is configured, OSPF on both routers sends a request to the local BFD server to initiate a BFD neighbor session with the OSPF neighbor router.

3 The BFD neighbor session with the OSPF neighbor router is established on both sides if BFD session limit is not reached.

* SW2.1 # show iproute

Ori Destination Gateway Mtr Flags VLAN Duration

#s 1 UG---Sbum--f- bp 0d:3h:34m:26s

#d 1 U------um--f- sumit 0d:3h:34m:28s

#oa 14 UG-D---um--f- sumit 0d:1h:16m:49s

#d 1 U------um--f- sumit_test 0d:1h:36m:28s

#d 1 U------um--f- v1 0d:3h:34m:28s

#d 1 U------um--f- bp 0d:3h:34m:28s

Origin(Ori): (b) BlackHole, (be) EBGP, (bg) BGP, (bi) IBGP, (bo) BOOTP,

(ct) CBT, (d) Direct, (df) DownIF, (dv) DVMRP, (e1) ISISL1Ext,

(e2) ISISL2Ext, (h) Hardcoded, (i) ICMP, (i1) ISISL1 (i2) ISISL2,

(is) ISIS, (mb) MBGP, (mbe) MBGPExt, (mbi) MBGPInter, (mp) MPLS Lsp,

(mo) MOSPF (o) OSPF, (o1) OSPFExt1, (o2) OSPFExt2,

(oa) OSPFIntra, (oe) OSPFAsExt, (or) OSPFInter, (pd) PIM-DM, (ps) PIM-SM,

(r) RIP, (ra) RtAdvrt, (s) Static, (sv) SLB_VIP, (un) UnKnown,

(*) Preferred unicast route (@) Preferred multicast route,

(#) Preferred unicast and multicast route.

Flags: (b) BFD protection requested, (B) BlackHole, (c) Compressed, (D) Dynamic,

(f) Provided to FIB, (G) Gateway, (H) Host Route, (l) Calculated LDP LSP,

(L) Matching LDP LSP, (m) Multicast, (p) BFD protection active, (P) LPM-routing,

(R) Modified, (s) Static LSP, (S) Static, (t) Calculated RSVP-TE LSP,

(T) Matching RSVP-TE LSP, (u) Unicast, (U) Up, (3) L3VPN Route.

MPLS Label: (S) Bottom of Label Stack

Mask distribution:

1 routes at length 8 2 routes at length 24

3 routes at length 32

Route Origin distribution:

4 routes from Direct 1 routes from Static

1 routes from OSPFIntra

Total number of routes = 6

Total number of compressed routes = 0

SW1.5 # show bfd session detail

Neighbor : Local :

VR-Name : VR-Default Interface : sumit

Session Type : Single Hop State : Up

Detect Time : 3000 ms Age : 760 ms

Discriminator (local/remote) : 4 / 4

Demand Mode (local/remote) : Off / Off

Poll (local/remote) : Off / Off

Tx Interval (local/remote) : 1000 / 1000 ms

Rx Interval (local/remote) : 1000 / 1000 ms

oper Tx Interval : 1000 ms

oper Rx Interval : 1000 ms

Multiplier (local/remote) : 3 / 3

Local Diag : 0 (No Diagnostic)

Remote Diag : 0 (No Diagnostic)

Authentication : None

Clients : OSPF

Uptime : 00 days 01 hours 35 minutes 30 seconds

Up Count : 1

Last Valid Packet Rx : 09:41:26.893554

Last Packet Tx : 09:41:27.360201

* SW1.6 #
Thanks a lot for the your expertise reply on this.