07-19-2013 10:27 AM - edited 03-07-2019 02:30 PM
Can anyone tell me why I am getting these inconsistent traceroute results from
one switch? Why does switch 172.23.31.8 trace fine to 172.23.30.1 but switch
172.23.31.6 is sent to the default route when tracing to 172.23.30.1 ?
See attached diagram. Thanks!
08-07-2013 11:24 AM
Anyone? Bueller?
08-07-2013 03:04 PM
Can u share config. There might be routes issue.
Jawad
08-09-2013 09:46 AM
The routing table looks normal. Switch 172.23.31.6 was recently replaced
due to hardware failure, and this strange behaviour seems to have started
with that replacement. Not sure what the problem is. Thanks.
show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is 172.23.31.1 to network 0.0.0.0
C 172.23.31.0 is directly connected, Vlan1
172.23.0.0/24 is subnetted, 2 subnets
D 172.23.30.0 [90/3072] via 192.168.2.2, 7w0d, Port-channel1
10.0.0.0/24 is subnetted, 7 subnets
D 10.90.155.0 [90/3072] via 192.168.2.21, 7w0d, Port-channel2
.
.
192.168.2.0/30 is subnetted, 8 subnets
C 192.168.2.0 is directly connected, Port-channel1
C 192.168.2.20 is directly connected, Port-channel2
.
.
S* 0.0.0.0/0 [1/0] via 172.23.31.1
Also, an updated diagram that fixes one typo.
08-09-2013 10:02 AM
Port connecting the new switch to that router, can you verify that they are configured correctly and match the settings on the router i.e duplex, speed etc. Also 172.23.31.1 firewall can you make sure that it is still not caching the mac of old switch still by any chance, you might have to clear that out. Other than the trace route do you have any performance issues on the clients that are connected to the 172.23.31.6 switch?
08-09-2013 11:33 AM
Switch ports look normal in all aspects. See below.
On the firewall, I don't see any ARP entries for the 172.23.31.6 or 172.23.31.8 switches
probably because those specific IPs don't often traverse that firewall for anything.
I see ARPs for clients connected to the 172.23.31.6 switch, though.
Yes, we are not able to connect to clients on the 172.23.30.0 subnet from
clients on the 172.23.31.6 switch (like with VLC or Dameware) because the packets
are being diverted to the firewall along the way and the firewall does not allow those
signals. The firewall does redirect pings and traceroute back to 172.23.31.4 however
because it does allow those and sends them back via a static route it has to the
172.23.30.0 subnet. I don't know why the router is getting confused about where to
forward packets from this one switch. Why is it sending them to it's default gateway
instead of what it knows in the routing table ???
Thanks for considering this strange issue...
Switch#sh run (excerpt)
interface GigabitEthernet0/52
switchport trunk encapsulation dot1q
switchport mode trunk
srr-queue bandwidth share 1 30 35 5
priority-queue out
mls qos trust cos
auto qos trust
macro description cisco-switch
spanning-tree link-type point-to-point
Switch#sh int Gi0/52
GigabitEthernet0/52 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseLX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:11, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
Router#sh run (excerpt)
interface GigabitEthernet1/0/52
switchport trunk encapsulation dot1q
switchport mode trunk
srr-queue bandwidth share 10 10 60 20
srr-queue bandwidth shape 10 0 0 0
queue-set 2
mls qos trust cos
macro description cisco-switch
auto qos voip trust
spanning-tree link-type point-to-point
Router#sh int GigabitEthernet1/0/52
GigabitEthernet1/0/52 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseLX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:08, output 00:00:19, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: