Very Very Weird Routing issue

Issues related to configuring your network
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ppage
Posts: 1
Joined: 2021/11/04 23:39:55

Very Very Weird Routing issue

Post by ppage » 2021/11/05 00:45:03

Hi,

Tearing my hair out and hoping someone can help. The issue is that I have an ethernet device port that I have configured 4 Vlans on. Each VLAN is in turn connected to a gateway (a different physical gateway for each VLAN). Three of the routes work fine, but the latest one, whilst traffic can reach the gateway, traffic could not reach the destination at the external side of the gateway.

Why the set up, I hear you ask... well each VLAN and gateway connects to a SIP trunk which is supplied by a different phone provider - 4 VLANs and 4 Gateways and 4 SIP media servers at the telco ends.

Aha you say - it sounds like the last route is not set up correctly. And I would say that the issue is that the route does not exist but the files are correct:

ifcfg-eth1.888
============
DEVICE=eth1.888
BOOTPROTO=static
ONBOOT='yes'
VLAN=yes
IPADDR=10.54.2.82
NETMASK=255.255.255.248
ZONE=external
DESCRIPTION="????????? SIP"
PEERDNS=no
IPV6_PEERDNS=no

and the route file is:
route-eth1.888
=============
GATEWAY0=10.54.2.81
NETMASK0=255.255.255.255
ADDRESS0=175.24.101.151

Despite me restarting the network services and then restarting the box the route just does not show when I do a route -n
The route file has been deleted and recreated from scratch without using cut and paste
But.... When I create the route temporarily using:
ip route add 175.24.101.151/32 via 10.54.2.81 dev eth1.888
As if by magic the route appears and works as expected, traffic routes and pings ping. But of course, this type of route will not survive a restart. So has anyone seen this before? Remember I have 3 other VLANs running off of device eth1 (eth1.585; eth1.557; eth1.589) and the networking is sound as it works if I use the ip route add command rather than use the route-eth1.888 file. All the other VLAN's are set up in the same way with virtually identical files apart from the Vlan number the description and the IP addresses and Netmasks.

Any ideas as I am completely stumped.
Phil

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jlehtone
Posts: 4523
Joined: 2007/12/11 08:17:33
Location: Finland

Re: Very Very Weird Routing issue

Post by jlehtone » 2021/11/05 15:22:46

ppage wrote:
2021/11/05 00:45:03
when I do a route -n
First a note: the 'ifconfig' and 'route' were supposedly superceded by more advanced iproute2 tools two decades ago.
I check current routes with ip ro. (I never learned to read the output of 'route' anyway. While I'm at it, netmasks are atrocious. Prefix, prefix, ...)

Initscripts, the network.service, the "ifup-scripts" calls 'ip'. You have a static route. There are two formats for static routes known by ifup-scripts.

The default network configuration system in EL7 is not network.service but NetworkManager.service.
With it a summary (which includes routes) can be seen with nmcli.
The nmcli c s and nmcli d s show connections and devices, respectively.

The first step is thus to figure out whether you have NetworkManager in use or not.
If yes, how does it see the config?

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