Cisco Switch with 4G router ISP

[Need Not To Know]

Hello all,

i have a problem.

i have 4G router from ISP and the port is connected to HP switch then one of HP ports connected to my Cisco Switch

when The power is off then on at 4G router .. the 4G router internet light became red and that's mean there is no internet

and after that i should disconnect Cisco Switch Port then re power the 4g router then connect Cisco switch port

after investigation 

if i disconnect the whole HP switch

and just take an ethernet cable from 4G router to cisco switch directly

the internet light still red and there is no internet

this is my cisco switch configuration

"

Xxx(config)#do show run
Building configuration...

Current configuration : 4272 bytes
!
! Last configuration change at 12:05:44 UTC Fri Apr 26 2024 by xxxxx
! NVRAM config last updated at 11:01:05 UTC Fri Apr 26 2024 by xxxxx
!
version 12.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname xxx 
!
boot-start-marker
boot-end-marker
!
enable secret 5 xxxxx.
!
username xxxxx password 7 xxxxx
aaa new-model
!
!
!
!
!
aaa session-id common
switch 1 provision ws-c3750-24ts
system mtu routing 1500
ip subnet-zero
ip routing
ip domain-name xxxxx.com
!
!
!
!
crypto pki trustpoint TP-self-signed-2726132480
enrollment selfsigned
subject-name cn=IOS-Self-Signed-Certificate-2726132480
revocation-check none
rsakeypair TP-self-signed-2726132480
!
!
crypto pki certificate chain TP-self-signed-2726132480
certificate self-signed 01
3082024C 308201B5 A0030201 02020101 300D0609 2A864886 F70D0101 04050030
31312F30 2D060355 04031326 494F532D 53656C66 2D536967 6E65642D 43657274
69666963 6174652D 32373236 31333234 3830301E 170D3933 30333031 30303030
34365A17 0D323030 31303130 30303030 305A3031 312F302D 06035504 03132649
4F532D53 656C662D 5369676E 65642D43 65727469 66696361 74652D32 37323631
33323438 3030819F 300D0609 2A864886 F70D0101 01050003 818D0030 81890281
8100D2D0 B3ACB990 3E42D659 7CFAE4CB E47F5AC7 AD4E0BD5 2F7248A6 E8C193CC
EBCD4F46 C107E8CC 4857C65A 145CD89D 2BF2672F 1FFB5048 6CDDDA3C 85DFC6C1
0E311DDF 546BFA40 468AEBEB CC95E78F 6CD9B824 4D948028 63EA779D A40B4E11
DF640A14 15DBAC5A 2A6A5C7A EAF343E7 4B07D707 2BFBD5F7 8A51A62D 62565C23
72650203 010001A3 74307230 0F060355 1D130101 FF040530 030101FF 301F0603
551D1104 18301682 14414D4D 5F43534F 5F4C6162 2E736974 612E636F 6D301F06
03551D23 04183016 801498E3 9B446238 C9153719 03B7C64D 69E89BE6 303B301D
0603551D 0E041604 1498E39B 446238C9 15371903 B7C64D69 E89BE630 3B300D06
092A8648 86F70D01 01040500 03818100 63A3C6A4 7D908D78 1BDF9077 0A05BE25
939F81AF 9589882C 5AE9527E F3C33585 F94C1266 C3581A4D 1CC25974 8A8C35E5
BB2962F3 B6EA5D15 58428ABD 645C6837 B537D582 9A7C62CF 43FE2C8E 36C159CD
5C9A5078 3A12D92D 276F153C 1F0504EF 75448637 4593175C 1425E457 0A35C94A
F9AAE937 BFA3F7CA D7325D42 247B97BB
quit
!
!
!
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
ip ssh version 2
!
!
interface FastEthernet1/0/1
switchport mode access
!
interface FastEthernet1/0/2
switchport mode access
!
interface FastEthernet1/0/3
switchport mode access
!
interface FastEthernet1/0/4
switchport mode access
!
interface FastEthernet1/0/5
switchport mode access
!
interface FastEthernet1/0/6
switchport mode access
!
interface FastEthernet1/0/7
switchport mode access
!
interface FastEthernet1/0/8
switchport mode access
!
interface FastEthernet1/0/9
switchport mode access
!
interface FastEthernet1/0/10
switchport mode access
!
interface FastEthernet1/0/11
switchport mode access
!
interface FastEthernet1/0/12
switchport mode access
!
interface FastEthernet1/0/13
switchport mode access
!
interface FastEthernet1/0/14
switchport mode access
!
interface FastEthernet1/0/15
switchport mode access
!
interface FastEthernet1/0/16
switchport mode access
!
interface FastEthernet1/0/17
switchport mode access
!
interface FastEthernet1/0/18
switchport mode access
!
interface FastEthernet1/0/19
switchport mode access
!
interface FastEthernet1/0/20
switchport mode access
!
interface FastEthernet1/0/21
switchport mode access
!
interface FastEthernet1/0/22
!
interface FastEthernet1/0/23
!
interface FastEthernet1/0/24
!
interface GigabitEthernet1/0/1
!
interface GigabitEthernet1/0/2
!
interface Vlan1
ip address 192.168.8.10 255.255.255.0
ip helper-address 192.168.8.1
!
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.8.1
ip http server
ip http secure-server
!
!
control-plane
!
banner motd ^C

**************************************************

Enjoy Your Time In xxxx

**************************************************^C
!
line con 0
password 7 xxxxx
logging synchronous
line vty 0 4
password 7 xxxxx
logging synchronous
transport input ssh
line vty 5 15
password 7 xxxxx
logging synchronous
!
end
"

is the problem with helper address of with ip domain?
or what plz?

Very important note: I've had a 4G router and an HP switch in my office for a long time, and I never encountered this problem until I purchased a Cisco switch

Cisco catalyst 3750

[balaji.bandi]

what 4G router ?

is the Router POE done using switch ?

how about you connect PC directly to 4G router, is that get internet, what IP the 4G router give to PC ?

on what port the 4G router connected on switch ?

[Need Not To Know]

I have a setup where the ISP router, which is a 4G router (not a fiber router), connects to an HP switch via its single port. Then, one of the HP switch ports is connected to my Cisco switch.

The ISP router assigns IP addresses from the subnet 192.168.8.x, with DHCP allocating addresses in the range of 192.168.8.100 to 192.168.8.200.

[balaji.bandi]

I have a setup where the ISP router, which is a 4G router (not a fiber router), connects to an HP switch via its single port. Then, one of the HP switch ports is connected to my Cisco switch.

we understand this and you mentioned in the first post, you also mentioned you removed HP switch and connected to Cisco switch directly 4G router, that where iam interested, what port these Router connected to Switch port

post that output here, show interface fasx/x (where the router connected)

if the switch acting like layer2, so that should work as expected.

[balaji.bandi]

we have asked some input have you got chance to read that questions ?

[MHM Cisco World]

Most likely there is L2 strom when you connect cisco SW this strom is make 4g router disable the port' 

The cisco SW or HP have any log of loop?

Do show interface in cisco SW abd check thr broadcast abd multicast count are it increase rapidly?

MHM

[Need Not To Know]

how can i show log of loop?

Do show interface in cisco SW abd check thr broadcast abd multicast count are it increase rapidly?(Don't understand what do u mean)

[Georg Pauwen]

Hello,

why do you have the Cisco switch configured as layer 3 ?

[Need Not To Know]

Hello,

it's Switch Layer 2

where is the configuration act as Layer 3 ?

[Need Not To Know]

I have removed helper address command, and the problem has been solved until now

is there any reason for that? or where was the problem?

[Need Not To Know]

@balaji.bandi 

@Georg Pauwen 

@MHM Cisco World 

can you help me to investigate the reason, and I'm sorry for bothering you.

[MHM Cisco World]

Ip helper address and ISP is down' and HP and cisco SW all lead to same point you have l2 strom' 

Must like Cisco SW and HP run different STP mode this make issue.

In cisco SW 

Show spanning tree

Show interface x/x <- do this command twice 

MHM

[Need Not To Know]

Now the problem has been solved after delete the helper address command, but i want your help to teach me where was the problem exactly

xxxx#show spanning-tree

VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 001a.a27d.7b00
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 001a.a27d.7b00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa1/0/1 Desg FWD 19 128.3 P2p

-------------------

xxxx#show ip int brief
Interface IP-Address OK? Method Status Protocol
Vlan1 192.168.8.10 YES manual up up
FastEthernet1/0/1 unassigned YES unset up up
FastEthernet1/0/2 unassigned YES unset down down
FastEthernet1/0/3 unassigned YES unset down down
FastEthernet1/0/4 unassigned YES unset down down
FastEthernet1/0/5 unassigned YES unset down down
FastEthernet1/0/6 unassigned YES unset down down
FastEthernet1/0/7 unassigned YES unset down down
FastEthernet1/0/8 unassigned YES unset down down
FastEthernet1/0/9 unassigned YES unset down down
FastEthernet1/0/10 unassigned YES unset down down
FastEthernet1/0/11 unassigned YES unset down down
FastEthernet1/0/12 unassigned YES unset down down
FastEthernet1/0/13 unassigned YES unset down down
FastEthernet1/0/14 unassigned YES unset down down
FastEthernet1/0/15 unassigned YES unset down down
FastEthernet1/0/16 unassigned YES unset down down
FastEthernet1/0/17 unassigned YES unset down down
FastEthernet1/0/18 unassigned YES unset down down
FastEthernet1/0/19 unassigned YES unset down down
FastEthernet1/0/20 unassigned YES unset down down
FastEthernet1/0/21 unassigned YES unset down down
FastEthernet1/0/22 unassigned YES unset down down
FastEthernet1/0/23 unassigned YES unset down down
FastEthernet1/0/24 unassigned YES unset down down
GigabitEthernet1/0/1 unassigned YES unset down down
GigabitEthernet1/0/2 unassigned YES unset down down

xxxx#show int FastEthernet1/0/1
FastEthernet1/0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 001a.a27d.7b03 (bia 001a.a27d.7b03)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:01, 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)
5 minute input rate 2000 bits/sec, 2 packets/sec
5 minute output rate 2000 bits/sec, 2 packets/sec
511527 packets input, 46056319 bytes, 0 no buffer
Received 507252 broadcasts (76728 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 76728 multicast, 0 pause input
0 input packets with dribble condition detected
432999 packets output, 35842128 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out