network issues

razamrazam Posts: 39Member ■■□□□□□□□□
Hello guys,

I have a network setup and facing few problems in it. would appreciate if anyone can give some suggestion in improving it.


Core Switch = 4506-E
Access Switches = 2960

all access switches connected to core using single 1G fiber uplink.

Vlan 100,
Core Switch =
Access Switches = onwards

Data (internet)
vlans used 10 to 30
each vlan for 5 access switches
vlan 10 = to vlan 30 =

DHCP Pools configured on Core Switch
default router for different vlans configured on the core switch (, ....

default gateway configured on all access switches is (management-ip address of core), should i keep this as a default gateway or should i change it to according to vlan (for example if access switch is in vlan 10, ip default gateway ?

dhcp snooping is configured, spanning tree port fast configured, storm control configured

1) when connect computer to any access switch port, i face few packet drops after every 20 to 25 responses.
2) from the core side when i try to telnet any access switch, some switches take 3 to 4 tries to respond. if i ping them they will not respond, will use show mac address command, will not be able to see mac of the switch on management vlan. after 3 to 4 tries i will get ping response and will be able to telnet and will be able to see mac on that core switch port. what can be the reason for this issue ?

any suggestions for improving the network ? anything else i can implement on it ?

thank you


  • EdTheLadEdTheLad Posts: 2,112Member ■■■■□□□□□□
    Some configs would be nice, your management network is vlan 100 so the DG on the switches is correct
    Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
  • mistabrumley89mistabrumley89 Posts: 356Member ■■■□□□□□□□
    What type of fiber cables are you using? SM or MM? Are your GBICS SM or MM? Not really enough to go on here, but just a couple basic things you can verify. Management VLAN should be fine to configure on your access switches. Can give us a copy of the log? Are ports flapping?
    Goals: WGU BS: IT-Sec (DONE) | CCIE Written: In Progress
  • razamrazam Posts: 39Member ■■□□□□□□□□
    fiber cable single mode, GBICs also single mode.. ports are not flapping

    please follow this post, same case..
  • tearofstearofs Posts: 112Member
    Use Wireshark or Tcpdump(Linux) to track what's going on behind the scenes.
  • thadizzythadizzy Posts: 72Member ■■□□□□□□□□
    What has this question got to do anything with the CCIE exam?
  • EdTheLadEdTheLad Posts: 2,112Member ■■■■□□□□□□
    I would actively encourage real network problems as opposed to how does this protocol work, after all that's why we are studying in the first place t be able to fix real networking issues. Also relevant for diagnostics section on new ccie v5.
    Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
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