difference in how 5304/5406 and 2626/2810 forward its packets

[Paulen]

All,

I have this strange issue that I can't find any good explanation for. Basically there seems to be some difference in how 5304/5406 and 2626/2810 forward its packets.

I have a setup with two Juniper routers and several ProCurve switches between. When I change management IP and def.gw to another subnet (I don't do routing on the switches) within the same VLAN of a 53/54 everything is fine. I reach my other router with no issues. But when I do the same trick on a 2510, 2626 or 2810 (i.e. adding another IP in same VLAN), I can't reach the other router. I have full connectivity and can reach the other switches in the same subnet. But not the def.gw.

This is actually a quite severe flaw, because there must be some issue with the forwarding database or the source/destination address.

Anyone else seen this?

[Holger Hasenaug]

If routing is disabled you need to set the primary vlan to the vlan you configured an IP address on and on which your default gateway should work.

Example:

ip default-gateway 1.1.1.254

vlan 1
name "DEFAULT_VLAN"
untagged 1-24
no ip address
exit

vlan 30
name "VLAN30"
tag 23,24
ip address 1.1.1.1 255.255.255.0
exit

primary-vlan 30

Have fun

[Paulen]

There must be something else. I have changed routers or default gateways several times, but this seems like a deadlock situation. The traffic seems to leave the MX router, but never returns. Typically the setup is like this:

[Router]--[5304]--[2626]--..--[Router]

So either the 2626 doesn't understand what comes from the Juniper router, or the traffic between the 2626 and the router is silently dropped by the 5304. I have tried rebooting and clearing arp etc.

[Paulen]

Just to clarify; the switch gets ARP for the router. I just can't ping it. (.2 is neighbor switch, .1 is router)

gn-xx-s1(vlan-99)# sho arp

IP ARP table

IP Address MAC Address Type Port
--------------- ----------------- ------- ----
10.20.26.1 001f12-8cf94c dynamic 23
10.20.26.2 001ffe-92a500 dynamic 23