host-identifier option problem
Sten Spans
sten at blinkenlights.nl
Fri Feb 20 14:32:27 UTC 2015
We've been quite happily using the option82 support with
ISC DHCPD 4.2.6 and a configuration similar to the following:
ubnet 172.16.0.0 netmask 255.255.255.0 {
option domain-name "mydomain";
}
host foobar {
option host-name "foobar";
host-identifier option agent.circuit-id "mccx-c1-p1-sw1";
fixed-address 172.16.0.131;
default-lease-time infinite;
max-lease-time infinite;
}
However we are now trying to configure option 82 on arista switches
and seem to have hit a snag. The dhcp daemon is refusing to hand out
leases to hosts matching the configured circuit-id's. The only difference
seems to be that arista switches generate requests with only a circuit-id,
but no remote-id.
Packets look like the following:
12.12.12.1.bootps > 123.123.123.32.bootps: BOOTP/DHCP, Request from
00:1c:73:40:74:35 (oui Unknown), length 277, hops 2, xid 0x5598377c, Flags
[none]
Gateway-IP 172.16.0.130
Client-Ethernet-Address 00:1c:73:40:74:35 (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Parameter-Request Option 55, length 13:
Subnet-Mask, BR, Time-Zone, Classless-Static-Route
Domain-Name, Domain-Name-Server, Hostname, YD
YS, NTP, MTU, Option 119
Default-Gateway
Agent-Information Option 82, length 16:
Circuit-ID SubOption 1, length 14: mccx-c1-p1-sw1
Note the missing remote-id. The result on the dhcpd side seems to be:
Feb 20 14:32:07 tlamdns2 dhcpd: DHCPDISCOVER from 00:1c:73:40:74:35 circuit-id mccx-c1-p1-sw1 via 172.16.0.130: network 172.16.0.0/24: no free leases
However if I manually generate a request (via tcpreplay)
which looks like this:
12.12.12.1.bootps > 123.123.123.32.bootps: BOOTP/DHCP, Request from
Request from e8:39:35:26:63:8e (oui Unknown), length 324, hops 1, xid 0x8,
secs 28, Flags [none]
Gateway-IP 172.16.0.130
Client-Ethernet-Address e8:39:35:26:63:8e (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether e8:39:35:26:63:8e
Parameter-Request Option 55, length 15:
Subnet-Mask, Time-Zone, Default-Gateway, Time-Server
Domain-Name-Server, Domain-Name, BR, Static-Route
NTP, Vendor-Option, Netbios-Name-Server, RN
RB, PRTR, MDHCP
Agent-Information Option 82, length 32:
Circuit-ID SubOption 1, length 14: mccx-c1-p1-sw1
Remote-ID SubOption 2, length 9: ^A^Gmccxsw5
Then I get:
Feb 20 14:37:14 mccmdns2 dhcpd: DHCPDISCOVER from e8:39:35:26:63:8e circuit-id mccx-c1-p1-sw1 remote-id 1:7:6d:63:63:78:73:77:35 via 172.16.0.130
Feb 20 14:37:14 mccmdns2 dhcpd: DHCPOFFER on 172.16.0.131 to e8:39:35:26:63:8e via 172.16.0.130
Anybody got a clue what's going wrong here?
I've been trying to spot the issue using the source,
but haven't been able to come up with anything so far.
--
Sten Spans
"There is a crack in everything, that's how the light gets in."
Leonard Cohen - Anthem
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